Adolescence

This article is about the video format. For other uses, see Adolescence (disambiguation).

Video Home System

Top view of a VHS cassette
Media type	Video recording media
Encoding	FM on magnetic tape; PAL, NTSC, SECAM
Read mechanism	Helical scan
Write mechanism	Helical scan
Developed by	JVC (Victor Company of Japan)
Usage	Home video, home movie, educational, feature films

VHS recorder, camcorder and cassette.

The Video Home System (VHS) is a standard for consumer-level analog video recording on tape cassettes. Developed by Victor Company of Japan (JVC) in the early 1970s, it was released in Japan in late 1976 and in the USA in early 1977.

From the 1950s, magnetic tape video recording became a major contributor to the television industry, via the first commercialized video tape recorders (VTRs). At that time, the devices were used only in expensive professional environments such as television studios and medical imaging (fluoroscopy). In the 1970s, videotape entered home use, creating the home video industry and changing the economics of the television and movie businesses. The television industry viewed videocassette recorders (VCRs) as having the power to disrupt their business, while television users viewed the VCR as the means to take control of their hobby.

In the 1980s and 1990s, at the peak of VHS's popularity, there were videotape format wars in the home video industry. Two of the formats, VHS and Betamax, received the most media exposure. VHS eventually won the war; dominating 60 percent of the North American market by 1980 and succeeding as the dominant home video format throughout the tape media period.

Optical disc formats later began to offer better quality than analog consumer video tape such as standard and super-VHS. The earliest of these formats, LaserDisc, was not widely adopted. However, after the introduction of the DVD format in 1997, VHS's market share began to decline. By 2008, DVD had achieved mass acceptance and replaced VHS as the preferred low end method of distribution.

History

Prior to VHS

Further information: Video tape recorder

After several attempts by other companies, the first commercially successful VTR, the Ampex VRX-1000, was introduced in 1956 by Ampex Corporation. At a price of US$50,000 in 1956 (over $400,000 in 2016's inflation), and US$300 (over $2,000 in 2016's inflation) for a 90-minute reel of tape, it was intended only for the professional market.

Kenjiro Takayanagi, a television broadcasting pioneer then working for JVC as its vice president, saw the need for his company to produce VTRs for the Japan market, and at a more affordable price. In 1959, JVC developed a two-head video tape recorder, and by 1960 a color version for professional broadcasting. In 1964, JVC released the DV220, which would be the company's standard VTR until the mid-1970s.

In 1969 JVC collaborated with Sony Corporation and Matsushita Electric (Matsushita was then parent company of Panasonic and is now known by that name, also majority stockholder of JVC until 2008) in building a video recording standard for the Japanese consumer. The effort produced the U-matic format in 1971, which was the first format to become a unified standard. U-matic was successful in business and some broadcast applications (such as electronic news-gathering), but due to cost and limited recording time very few of the machines were sold for home use.

Soon after, Sony and Matsushita broke away from the collaboration effort, in order to work on video recording formats of their own. Sony started working on Betamax, while Matsushita started working on VX. JVC released the CR-6060 in 1975, based on the U-matic format. Sony and Matsushita also produced U-matic systems of their own.

VHS development

In 1971, JVC engineers Yuma Shiraishi and Shizuo Takano put together a team to develop a consumer-based VTR. By the end of 1971 they created an internal diagram titled "VHS Development Matrix", which established twelve objectives for JVC's new VTR. These included:

• The system must be compatible with any ordinary television set.
• Picture quality must be similar to a normal air broadcast.
• The tape must have at least a two-hour recording capacity.
• Tapes must be interchangeable between machines.
• The overall system should be versatile, meaning it can be scaled and expanded, such as connecting a video camera, or dub between two recorders.
• Recorders should be affordable, easy to operate and have low maintenance costs.
• Recorders must be capable of being produced in high volume, their parts must be interchangeable, and they must be easy to service.

In early 1972 the commercial video recording industry in Japan took a financial hit. JVC cut its budgets and restructured its video division, shelving the VHS project. However, despite the lack of funding, Takano and Shiraishi continued to work on the project in secret. By 1973 the two engineers had produced a functional prototype.

Competition with Betamax

In 1974, the Japanese Ministry of International Trade and Industry (MITI), desiring to avoid consumer confusion, attempted to force the Japanese video industry to standardize on just one home video recording format. Later, Sony had a functional prototype of the Betamax format, and was very close to releasing a finished product. With this prototype, Sony persuaded the MITI to adopt Betamax as the standard, and allow it to license the technology to other companies.

JVC believed that an open standard, with the format shared among competitors without licensing the technology, was better for the consumer. To prevent the MITI from adopting Betamax, JVC worked to convince other companies, in particular Matsushita (Japan's largest electronics manufacturer at the time, marketing its products under the National brand in most territories and the Panasonic brand in North America, and JVC's majority stockholder), to accept VHS, and thereby work against Sony and the MITI. Matsushita agreed, primarily out of concern that Sony might become the leader in the field if its proprietary Betamax format was the only one allowed to be manufactured. Matsushita also regarded Betamax's one-hour recording time limit as a disadvantage.

Matsushita's backing of JVC persuaded Hitachi, Mitsubishi, and Sharp to back the VHS standard as well. Sony's release of its Betamax unit to the Japanese market in 1975 placed further pressure on the MITI to side with the company. However, the collaboration of JVC and its partners was much stronger, and eventually led the MITI to drop its push for an industry standard. JVC released the first VHS machines in Japan in late 1976, and in the United States in early 1977.

Sony's Betamax competed with VHS throughout the late 1970s and into the 1980s (see Videotape format war). Betamax's major advantages were its smaller cassette size, higher video quality, and earlier availability but its shorter recording time proved to be a major shortcoming.

Originally, Beta I machines using the NTSC television standard were able to record one hour of programming at their standard tape speed of 1.5 inches per second (ips). The first VHS machines could record for two hours, due to both a slightly slower tape speed (1.31 ips.) and significantly longer tape. Betamax's smaller-sized cassette limited the size of the reel of tape, and could not compete with VHS's two-hour capability by extending the tape length. Instead, Sony had to slow the tape down to 0.787 ips (Beta II) in order to achieve two hours of recording in the same cassette size. This reduced Betamax's once-superior video quality to worse than VHS when comparing two-hour recording. Sony eventually released an extended Beta cassette (Beta III) which allowed NTSC Betamax to break the two-hour limit, but by then VHS had already won the format battle.

Additionally, VHS had a "far less complex tape transport mechanism" than Betamax, and VHS machines were faster at rewinding and fast-forwarding than their Sony counterparts.

In machines using the PAL and SECAM television formats, Beta's running time was similar to VHS, the quality at least as good, and the format battle was not fought on running time.

Initial releases of VHS-based devices

JVC HR-3300U VIDSTAR – the United States version of the JVC HR-3300. It is virtually identical to the Japan version. Japan's version showed the "Victor" name, and didn't use the "VIDSTAR" name.

The first VCR to use VHS was the Victor HR-3300, and was introduced by the president of JVC in Japan on September 9, 1976. JVC started selling the HR-3300 in Akihabara, Tokyo, Japan on October 31, 1976. Region-specific versions of the JVC HR-3300 were also distributed later on, such as the HR-3300U in the United States, and HR-3300EK in the United Kingdom. The United States received its first VHS-based VCR – the RCA VBT200 on August 23, 1977. The RCA unit was designed by Matsushita, and was the first VHS-based VCR manufactured by a company other than JVC. It was also capable of recording four hours in LP (long play) mode. The United Kingdom later received its first VHS-based VCR – the Victor HR-3300EK in 1978.

Quasar and General Electric would follow-up with VHS-based VCRs – all designed by Matsushita. By 1999, Matsushita alone produced just over half of all Japanese VCRs.

Technical details

Cassette and tape design

Top view of VHS with front casing removed

The VHS cassette is a 187 mm wide, 103 mm deep, 25 mm thick (73⁄8 × 41⁄16 × 1 inch) plastic shell held together with five Phillips head screws. The flip-up cover that protects the tape has a built-in latch with a push-in toggle on the right side (bottom view image). The VHS cassette also includes an anti-despooling mechanism consisting of several plastic parts between the plastic spools, near the front of the tape (white and black in the top view). The spool latches are released by a push-in lever within a 6.35 mm (¼ inch) hole accessed from the bottom of the cassette, 19 mm (¾ inch) inwards from the edge label.

There is a clear tape leader at both ends of the tape to provide an optical auto-stop for the VCR transport mechanism. A light source is inserted into the cassette through the circular hole in the center of the underside when loaded in the VCR, and two photodiodes are located to the left and right sides of where the tape exits the cassette. When the clear tape reaches one of these, enough light will pass through the tape to the photodiode to trigger the stop function; in more sophisticated machines it will start rewinding the cassette when the trailing end is detected. Early VCRs used an incandescent bulb as the light source, which regularly failed and caused the VCR to erroneously think that a cassette is loaded when empty, or would detect the blown bulb and stop functioning completely. Later designs use an infrared LED which had a much longer lifetime.

The recording media is a 12.7 mm (½ inch) wide, approximately 800 foot long Oxide-coated Mylar magnetic tape that is wound between two spools, allowing it to be slowly passed over the various playback and recording heads of the video cassette recorder. The tape speed for "Standard Play" mode (see below) is 3.335 cm/s (1.313 ips) for NTSC, 2.339 cm/s (0.921 ips) for PAL—or just over 2.0 and 1.4 metres (6 ft 6.7 in and 4 ft 7.2 in) per minute respectively.

Tape loading technique

VHS M-loading system.

As with almost all cassette-based videotape systems, VHS machines pull the tape out from the cassette shell and wrap it around the inclined head drum which rotates at 1798.2 rpm in NTSC machines and at 1500 rpm for PAL, one complete rotation of the head corresponding to one video frame. VHS uses an "M-loading" system, also known as M-lacing, where the tape is drawn out by two threading posts and wrapped around more than 180 degrees of the head drum (and also other tape transport components) in a shape roughly approximating the letter M.

Recording capacity

The interior of a modern VHS VCR showing the drum and tape.

A VHS cassette holds a maximum of about 430 m (1,410 ft.) of tape at the lowest acceptable tape thickness, giving a maximum playing time of about four hours in a T-240/DF480 for NTSC and five hours in an E-300 for PAL at "standard play" (SP) quality. More frequently however, VHS tapes are thicker than the required minimum to avoid complications such as jams or tears in the tape. Other speeds include "long play" (LP), and "extended play" (EP) or "super long play" (SLP) (standard on NTSC; rarely found on PAL machines). For NTSC, LP and EP/SLP doubles and triples the recording time accordingly, but these speed reductions cause a reduction in video quality – from the normal 250 lines in SP, to 230 analog lines horizontal in LP and even less in EP/SLP. The slower speeds cause a very noticeable reduction in linear (non-hifi) audio track quality as well, as the linear tape speed becomes much lower than what is commonly considered a satisfactory minimum for audio recording.

Tape lengths

Both NTSC and PAL/SECAM VHS cassettes are physically identical (although the signals recorded on the tape are incompatible). However, as tape speeds differ between NTSC and PAL/SECAM, the playing time for any given cassette will vary accordingly between the systems. In order to avoid confusion, manufacturers indicate the playing time in minutes that can be expected for the market the tape is sold in. It is perfectly possible to record and play back a blank T-XXX tape in a PAL machine or a blank E-XXX tape in an NTSC machine, but the resulting playing time will be different from that indicated.

To calculate the playing time for a T-XXX tape in a PAL machine, use this formula: PAL/SECAM Recording Time = T-XXX in minutes * (1.426)

To calculate the playing time for an E-XXX tape in an NTSC machine, use this formula: NTSC Recording Time = E-XXX in minutes * (0.701)

Some new Panasonic NTSC/ATSC recorders also include a XP mode which is not part of the official specification. It enables recordings at double the SP speed, such that a T-180 holds 1.5 hours.

• E-XXX indicates playing time in minutes for PAL or SECAM in SP and LP speeds.
• T-XXX indicates playing time in minutes for NTSC or PAL-M in SP, LP, and EP/SLP speeds.
• SP is Standard Play, LP is Long Play (½ speed, equal to recording time in DVHS "HS" mode), EP/SLP is extended/super long play (⅓ speed) which was primarily released into the NTSC market.

Common tape lengths

Tape label (nominal length in minutes)	Tape length		Rec. time (NTSC)			Rec. time (PAL)
	m	ft	SP	LP	EP/SLP	SP	LP
NTSC market
T-20	44	145	22 min	44 min	66 min (1h 06)	31.5 min	63 min
T-30 (typical VHS-C)	63	207	31.5 min	63 min (1h 03)	95 min (1h 35)	45 min	90 min (1h 30)
T-45	94	310	47 min	94 min (1h 34)	142 min (2h 22)	67 min (1h 07)	135 min (2h 15)
T-60	126	412	63 min (1h 03)	126 min (2h 06)	188 min (3h 08)	89 min (1h 29)	179 min (2h 59)
T-90	186	610	93 min (1h 33)	186 min (3h 06)	279 min (4h 39)	132 min (2h 12)	265 min (4h 25)
T-120 / DF240	247	811	124 min (2h 04)	247 min (4h 07)	371 min (6h 11)	176 min (2h 56)	352 min (5h 52)
T-140	287.5	943	144 min (2h 24)	287 min (4h 47)	431 min (7h 11)	204.5 min (3h 24.5)	404.5 min (6h 44.5)
T-150 / DF300	316.5	1040	158 min (2h 38)	316 min (5h 16)	475 min (7h 55)	226 min (3h 46)	452 min (7h 32)
T-160	328	1075	164 min (2h 44)	327 min (5h 27)	491 min (8h 11)	233 min (3h 53)	467 min (7h 47)
T-180 / DF-360	369	1210	184 min (3h 04)	369 min (6h 09)	553 min (9h 13)	263 min (4h 23)	526 min (8h 46)
T-200	410	1345	205 min (3h 25)	410 min (6h 50)	615 min (10h 15)	292 min (4h 52)	584 min (9h 44)
T-210 / DF420	433	1420	216 min (3h 36)	433 min (7h 13)	649 min (10h 49)	308 min (5h 08)	617 min (10h 17)
T-240 / DF480	500	1640	250 min (4h 10)	500 min (8h 20)	749 min (12h 29)	356 min (5h 56)	712 min (11h 52)
PAL market
E-30 (typical VHS-C)	45	148	22.5 min	45 min	68 min (1h 08)	32 min	64 min (1h 04)
E-60	88	290	44 min	88 min (1h 28)	133 min (2h 13)	63 min (1h 03)	126 min (2h 06)
E-90	131	429	65 min (1h 05)	131 min (2h 11)	196 min (3h 16)	93 min (1h 33)	186 min (3h 06)
E-120	174	570	87 min (1h 27)	174 min (2h 54)	260 min (4h 20)	124 min (2h 04)	248 min (4h 08)
E-150	216	609	108 min (1h 49)	227 min (3h 37)	324 min (5h 24)	154 min (2h 34)	308 min (5h 08)
E-180	259	849	129 min (2h 09)	259 min (4h 18)	388 min (6h 28)	184 min (3h 04)	369 min (6h 09)
E-195	279	915	139 min (2h 19)	279 min (4h 39)	418 min (6h 58)	199 min (3h 19)	397 min (6h 37)
E-200	289	935	144 min (2h 24)	284 min (4h 44)	428 min (7h 08)	204 min (3h 24)	405 min (6h 45)
E-210	304	998	152 min (2h 32)	304 min (5h 04)	456 min (7h 36)	217 min (3h 37)	433 min (7h 13)
E-240	348	1142	174 min (2h 54)	348 min (5h 48)	522 min (8h 42)	248 min (4h 08)	496 min (8h 16)
E-270	392	1295	196 min (3h 16)	392 min (6h 32)	589 min (9h 49)	279 min (4h 39)	559 min (9h 19)
E-300	435	1427	217 min (3h 37)	435 min (7h 15)	652 min (10h 52)	310 min (5h 10)	620 min (10h 20)

As manufacturers tend to err on the side of generosity when cutting tapes to length (for example, a 412 ft "T-60" is in fact nearly 63 minutes long) in order to account for manufacturing errors and slight differences in deck spindle speed and spool-out, it is quite likely that some of these cassettes—for example, DF420 and E300, or E30 and T20—are actually manufactured to the same true length internally and are merely stamped with the same nominal length for sales purposes.

Several other defined lengths of cassette entered mass production for both markets, but were either used only for professional duplication purposes (often pushing the limit of how much tape of a particular grade/thickness could fit into a standard cassette, in order to hold films that could not quite fit onto a shorter standard size without risking poorer quality or reliability by switching to a thinner grade), or failed to find popularity amongst home consumers because of a glut of tape length choices or poor value for money—e.g. T130/135/140, T168, E150, E270, and more besides.

Copy Protection

As VHS was designed to facilitate recording from various sources, including television broadcasts or other VCR units, content producers quickly found that home users were able to use the devices to copy videos from one tape to another. Despite the generation loss, this was regarded as a widespread problem, which the members of the Motion Picture Association of America (MPAA) claimed caused them great financial losses. In response, several companies developed technologies to protect copyrighted VHS tapes from casual duplication by home users.

The most popular method was Macrovision, produced by a company of the same name. According to Macrovision, "The technology is applied to over 550 million videocassettes annually and is used by every MPAA movie studio on some or all of their videocassette releases. Over 220 commercial duplication facilities around the world are equipped to supply Macrovision videocassette copy protection to rights owners." Also, "The study found that over 30% of VCR households admit to having unauthorized copies, and that the total annual revenue loss due to copying is estimated at $370,000,000 annually." The system was first used in copyrighted movies beginning with the 1984 film The Cotton Club.

Macrovision copy protection saw refinement throughout its years, but has always worked by essentially introducing deliberate errors into a protected VHS tape's output video stream. These errors in the output video stream are ignored by most televisions, but will interfere with re-recording of programming by a second VCR. The first version of Macrovision introduces voltage spikes during the vertical blanking interval, which occurs between the video fields. These high levels confuse the automatic gain control circuit in most VHS VCRs, leading to varying brightness levels in an output video, but are ignored by the TV as they are out of the frame-display period. "Level II" Macrovision uses a process called "colorstriping," which inverts the analog signal's colorburst period and causes off-color bands to appear in the picture. Level III protection added additional colorstriping techniques to further degrade the image.

These protection methods worked well to defeat analog-to-analog copying by VCRs of the time. Products capable of digital video recording are mandated by law to include features which detect Macrovision encoding of input analog streams, and reject copying of the video. Both intentional and false-positive detection of Macrovision protection has frustrated archivists who wish to copy now-fragile VHS tapes to a digital format for preservation.

Recording process

A close-up process of how the magnetic tape in a VHS cassette is being pulled from the cassette shell to the head drum of the VCR.

This illustration demonstrates the helical wrap of the tape around the head drum, and shows the points where the video, audio and control tracks are recorded.

The recording process in VHS consists of the following steps, in this order:

• The tape is pulled from the supply reel by a capstan and pinch roller, similar to those used in audio tape recorders.
• The tape passes across the erase head, which wipes any existing recording from the tape.
• The tape is wrapped around the head drum, using a little more than 180 degrees of the drum.
• One of the heads on the spinning drum records one field of video onto the tape, in one diagonally oriented track.
• The tape passes across the audio and control head, which records the control track and the linear audio track or tracks.
• The tape is wound onto the take-up reel due to torque applied to the reel by the machine.

Erase head

The erase head is fed by a high level, high frequency AC signal that overwrites any previous recording on the tape. Without this step, the new recording cannot be guaranteed to completely replace any old recording that might have been on the tape.

Video recording

A typical VHS head drum containing two tape heads. (1) is the upper head, (2) is the tape heads, and (3) is the head amplifier.

The underside of a typical 4-head VHS head assembly showing the head chips.

A typical RCA (Model CC-4371) Full-Size VHS Camcorder with a built-in three-inch color LCD screen. The tiltable LCD screen is rare on full-size VHS camcorders; only the smaller VHS-C camcorders are more common to have a tiltable LCD screen on some units.

The tape path then carries the tape around the spinning head drum, wrapping it around a little more than 180 degrees (called the omega transport system) in a helical fashion, assisted by the slanted tape guides. The head rotates constantly at approximately 1800 rpm in NTSC machines, exactly 1500 in PAL, each complete rotation corresponding to one frame of video.

Two tape heads are mounted on the cylindrical surface of the drum, 180 degrees apart from each other, so that the two heads "take turns" in recording. The rotation of the head drum, combined with the relatively slow movement of the tape, results in each head recording a track oriented at a diagonal with respect to the length of the tape. This is referred to as helical scan recording.

To maximize the use of the tape, the video tracks are recorded very close together to each other. To reduce crosstalk between adjacent tracks on playback, an azimuth recording method is used: The gaps of the two heads are not aligned exactly with the track path. Instead, one head is angled at plus seven degrees from the track, and the other at minus seven degrees. This results, during playback, in destructive interference of the signal from the tracks on either side of the one being played.

Each of the diagonal-angled tracks is a complete TV picture field, lasting 1/60th of a second (1/50th on PAL) on the display. One tape head records an entire picture field. The adjacent track, recorded by the second tape head, is another 1/60th or 1/50th of a second TV picture field, and so on. Thus one complete head rotation records an entire NTSC or PAL frame of two fields.

The original VHS specification had only two video heads. Later models implemented at least one more pair of heads, which were used at (and optimized for) the EP tape speed. In machines supporting VHS HiFi (described later), yet another pair of heads was added to handle the VHS HiFi signal.

The high tape-to-head speed created by the rotating head results in a far higher bandwidth than could be practically achieved with a stationary head. VHS tapes have approximately 3 MHz of video bandwidth and 400 kHz of chroma bandwidth. The luminance (black and white) portion of the video is recorded as a frequency modulated, with a down-converted "color under" chroma (color) signal recorded directly at the baseband. Each helical track contains a single field ('even' or 'odd' field, equivalent to half a frame) encoded as an analog raster scan, similar to analog TV broadcasts. The horizontal resolution is 240 lines per picture height, or about 320 lines across a scan line, and the vertical resolution (the number of scan lines) is the same as the respective analog TV standard (576 for PAL or 486 for NTSC; usually, somewhat fewer scan lines are actually visible due to overscan). In modern-day digital terminology, NTSC VHS is roughly equivalent to 333×480 pixels luma and 40×480 chroma resolutions (333×480 pixels=159,840 pixels or 0.16MP (1/6 of a MegaPixel))., while PAL VHS offers the equivalent of about 335×576 pixels luma and 40×240 chroma (the vertical chroma resolution of PAL is limited by the PAL color delay line mechanism).

JVC would counter 1985's SuperBeta with VHS HQ, or High Quality. The frequency modulation of the VHS luminance signal is limited to 3 megahertz, which makes higher resolutions technically impossible even with the highest-quality recording heads and tape materials, but an HQ branded deck includes luminance noise reduction, chroma noise reduction, white clip extension, and improved sharpness circuitry. The effect was to increase the apparent horizontal resolution of a VHS recording from 240 to 250 analog (equivalent to 333 pixels from left-to-right, in digital terminology). The major VHS OEMs resisted HQ due to cost concerns, eventually resulting in JVC reducing the requirements for the HQ brand to "white clip extension plus one other improvement."

In 1987, JVC introduced a new format called Super VHS (often known as S-VHS) which extended the bandwidth to over 5 megahertz, yielding 420 analog horizontal (560 pixels left-to-right). Most Super VHS recorders can play back standard VHS tapes, but not vice versa. S-VHS was designed for higher resolution, but failed to gain popularity outside Japan because of the high costs of the machines and tapes. Because of the limited user base, Super VHS was never picked up to any significant degree by manufacturers of pre-recorded tapes, although it was used extensively in the low-end professional market for filming and editing.

Audio recording

After leaving the head drum, the tape passes over the stationary audio and control head. This records a control track at the bottom edge of the tape, and one or two linear audio tracks along the top edge.

Original linear audio system

In the original VHS specification, audio was recorded as baseband in a single linear track, at the upper edge of the tape, similar to how an audio compact cassette operates. The recorded frequency range was dependent on the linear tape speed. For the VHS SP mode, which already uses a lower tape speed than the compact cassette, this resulted in a mediocre frequency response of roughly 100 Hz to 10 kHz for NTSC; frequency response for PAL VHS with its lower standard tape speed was somewhat worse. The signal-to-noise ratio (SNR) was an acceptable 42 dB. Both parameters degraded significantly with VHS's longer play modes, with EP/NTSC frequency response peaking at 4 kHz.

Audio cannot be recorded on a VHS tape without recording a video signal, even in the audio dubbing mode. If there is no video signal to the VCR input, most VCRs will record black video as well as generate a control track while the audio is being recorded. Some early VCRs would record audio without a control track signal, but this was of little practical use since the absence of a control track signal meant that the linear tape speed was irregular during playback.

More expensive decks offered stereo audio recording and playback. Linear stereo, as it was called, fit two independent channels in the same space as the original mono audiotrack. While this approach preserved acceptable backward compatibility with monoaural audio heads, the splitting of the audio track degraded the signal's SNR to the point that audible tape hiss was objectionable at normal listening volume. To counteract tape hiss, decks applied Dolby B noise reduction for recording and playback. Dolby B dynamically boosts the mid-frequency band of the audio program on the recorded medium, improving its signal strength relative to the tape's background noise floor, then attenuates the mid-band during playback. Dolby B is not a transparent process, and Dolby-encoded program material will exhibit an unnatural mid-range emphasis when played on non-Dolby capable VCRs.

High-end consumer recorders took advantage of the linear nature of the audio track, as the audio track could be erased and recorded without disturbing the video portion of the recorded signal. Hence, "audio dubbing" and "video dubbing", where either the audio or video are re-recorded on tape (without disturbing the other), were supported features on prosumer linear video editing-decks. Without dubbing capability, an audio or video edit could not be done in-place on master cassette, and requires the editing output be captured to another tape, incurring generational loss.

Studio film releases began to emerge with linear stereo audiotracks in 1982. From that point onward nearly every home video release by Hollywood featured a Dolby-encoded linear stereo audiotrack. However, linear stereo was never popular with equipment makers or consumers.

Tracking adjustment and index marking

Another linear control track, at the tape's lower edge, holds pulses that mark the beginning of every frame of video; these are used to fine-tune the tape speed during playback, so that the high speed rotating heads remained exactly on their helical tracks rather than somewhere between two adjacent tracks (known as "tracking"). Since good tracking depends on precise distances between the rotating drum and the fixed control/audio head reading the linear tracks, which usually varies by a couple of micrometers between machines due to manufacturing tolerances, most VCRs offer tracking adjustment, either manual or automatic, to correct such mismatches.

The control track is also used to hold index marks, which were normally written at the beginning of each recording session, and can be found using the VCR's index search function: this will fast-wind forward or backward to the nth specified index mark, and resume playback from there. At times, higher-end VCRs provided functions for the user to manually add and remove these marks — so that, for example, they coincide with the actual start of the television program — but this feature later became hard to find.

By the late 1990s, some high-end VCRs offered more sophisticated indexing. For example, Panasonic's Tape Library system assigned an ID number to each cassette, and logged recording information (channel, date, time and optional program title entered by the user) both on the cassette and in the VCR's memory for up to 900 recordings (600 with titles).

Hi-Fi audio system

Around 1984, JVC added Hi-Fi audio to VHS (model HR-D725U, in response to Betamax's introduction of Beta Hi-Fi.) Both VHS Hi-Fi and Betamax Hi-Fi delivered flat full-range frequency response (20 Hz to 20 kHz), excellent 70 dB signal-to-noise ratio (in consumer space, second only to the compact disc), dynamic range of 90 dB, and professional audio-grade channel separation (more than 70 dB). VHS Hi-Fi audio is achieved by using audio frequency modulation (AFM), modulating the two stereo channels (L, R) on two different frequency-modulated carriers and embedding the combined modulated audio signal pair into the video signal. To avoid crosstalk and interference from the primary video carrier, VHS's implementation of AFM relied on a form of magnetic recording called depth multiplexing. The modulated audio carrier pair was placed in the hitherto-unused frequency range between the luminance and the color carrier (below 1.6 MHz), and recorded first. Subsequently, the video head erases and re-records the video signal (combined luminance and color signal) over the same tape surface, but the video signal's higher center frequency results in a shallower magnetization of the tape, allowing both the video and residual AFM audio signal to coexist on tape. (PAL versions of Beta Hi-Fi use this same technique). During playback, VHS Hi-Fi recovers the depth-recorded AFM signal by subtracting the audio head's signal (which contains the AFM signal contaminated by a weak image of the video signal) from the video head's signal (which contains only the video signal), then demodulates the left and right audio channels from their respective frequency carriers. The end result of the complex process was audio of outstanding fidelity, which was uniformly solid across all tape-speeds (EP, LP or SP.) Since JVC had gone through the complexity of ensuring Hi-Fi's backward compatibility with non-Hi-Fi VCRs, virtually all studio home video releases produced after this time contained Hi-Fi audio tracks, in addition to the linear audio track. Under normal circumstances, all Hi-Fi VHS VCRs will record Hi-Fi and linear audio simultaneously to ensure compatibility with VCRs without Hi-Fi playback, though only early high-end Hi-Fi machines provided linear stereo compatibility.

Due to the path followed by the video and Hi-Fi audio heads being striped and discontinuous—unlike that of the linear audio track—head-switching is required to provide a continuous audio signal. While the video signal can easily hide the head-switching point in the invisible vertical retrace section of the signal, so that the exact switching point is not very important, the same is obviously not possible with a continuous audio signal that has no inaudible sections. Hi-Fi audio is thus dependent on a much more exact alignment of the head switching point than is required for non-HiFi VHS machines. Misalignments may lead to imperfect joining of the signal, resulting in low-pitched buzzing. The problem is known as "head chatter", and tends to increase as the audio heads wear down.

The sound quality of Hi-Fi VHS stereo is comparable to the quality of CD audio, particularly when recordings were made on high-end or professional VHS machines that have a manual audio recording level control. This high quality compared to other consumer audio recording formats such as compact cassette attracted the attention of amateur and hobbyist recording artists. Home recording enthusiasts occasionally recorded high quality stereo mixdowns and master recordings from multitrack audio tape onto consumer-level Hi-Fi VCRs. However, because the VHS Hi-Fi recording process is intertwined with the VCR's video-recording function, advanced editing functions such as audio-only or video-only dubbing are impossible. A short-lived alternative to the hifi feature for recording mixdowns of hobbyist audio-only projects was a PCM adaptor so that high-bandwidth digital video could use a grid of black-and-white dots on an analog video carrier to give pro-grade digital sounds though DAT tapes made this obsolete.

Some VHS decks also had a "simulcast" switch, allowing users to record an external audio input along with off-air pictures. Some televised concerts offered a stereo simulcast soundtrack on FM radio and as such, events like Live Aid were recorded by thousands of people with a full stereo soundtrack despite the fact that stereo TV broadcasts were some years off (especially in regions that adopted NICAM). Other examples of this included network television shows such as Friday Night Videos and MTV for its first few years in existence. Likewise, some countries, most notably South Africa, provided alternate language audio tracks for TV programming through an FM radio simulcast.

The considerable complexity and additional hardware limited VHS Hi-Fi to high-end decks for many years. While linear stereo all but disappeared from home VHS decks, it was not until the 1990s that Hi-Fi became a more common feature on VHS decks. Even then, most customers were unaware of its significance and merely enjoyed the better audio performance of the newer decks.

Variations

Victor S-VHS (left) and S-VHS-C (right).

Super-VHS / ADAT / SVHS-ET

Main articles: S-VHS and D-VHS

Several improved versions of VHS exist, most notably Super-VHS (S-VHS), an analog video standard with improved video bandwidth. S-VHS improved the horizontal luminance resolution to 400 lines (versus 250 for VHS/Beta and 500 for DVD). The audio-system (both linear and AFM) is the same. S-VHS made little impact on the home market, but gained dominance in the camcorder market due to its superior picture quality.

The ADAT format provides the ability to record multitrack digital audio using S-VHS media. JVC also developed SVHS-ET technology for its Super-VHS camcorders and VCRs, which simply allows them to record Super VHS signals onto lower-priced VHS tapes, albeit with a slight blurring of the image. Nearly all later Super-VHS camcorders and VCRs have SVHS-ET ability.

VHS-C / Super VHS-C

Main article: VHS-C

Another variant is VHS-Compact (VHS-C), originally developed for portable VCRs in 1982, but ultimately finding success in palm-sized camcorders. The longest tape available for NTSC holds 60 minutes in SP mode and 180 minutes in EP mode. Since VHS-C tapes are based on the same magnetic tape as full-size tapes, they can be played back in standard VHS players using a mechanical adapter, without the need of any kind of signal conversion. The magnetic tape on VHS-C cassettes is wound on one main spool and uses a gear wheel to advance the tape.

The adapter is mechanical, although early examples were motorized, with a battery. It has an internal hub to engage with the VCR mechanism in the location of a normal full-size tape hub, driving the gearing on the VHS-C cassette. Also, when a VHS-C cassette is inserted into the adapter, a small swing-arm pulls the tape out of the miniature cassette to span the standard tape path distance between the guide rollers of a full-size tape. This allows the tape from the miniature cassette to use the same loading mechanism as that from the standard cassette.

Super VHS-C or S-VHS Compact was developed by JVC in 1987. S-VHS provided an improved luminance and chrominance quality, yet S-VHS recorders were compatible with VHS tapes.

Sony was unable to shrink its Betamax form any further, so instead developed Video8/Hi8 which was in direct competition with the VHS-C/S-VHS-C format throughout the 80s, 90s, and 2000s. Ultimately neither format "won" and both have been superseded by digital high definition equipment.

VHS single

VHS single, also known as videotape single or Video 45s (a play on the term "45" when used to describe vinyl records) is a music single, using a standard-sized VHS cartridge. The format has existed since the early 1980s. In 1983, British synthpop band The Human League released the UK's first commercial video single on both VHS and Betamax as "The Human League Video Single". It was not a huge commercial success due to the high retail price of £10.99, compared to £1.99 for a vinyl single.

The VHS single format gained higher levels of mainstream popularity when Madonna released "Justify My Love" as a video single in 1990 following the blacklisting of the video by MTV. U2 also released "Numb", the lead single from their 1993 album Zooropa as a video single.

Despite the success of these releases, the video single struggled as its releases were relatively rare, the technology slowly being superseded first by CD Video (which proved unsuccessful due to the cost of capable LaserDisc players to play the video portion), music CDs with computer-accessible video files, then, by the early 2000s, by both DVD singles and CD+DVD releases. VHS tapes were however marketed to distribute music video compilations.

W-VHS / Digital-VHS (high-definition)

Main articles: W-VHS and D-VHS

W-VHS allowed recording of MUSE Hi-Vision analog high definition television, which was broadcast in Japan from 1989 until 2007. The other improved standard, called Digital-VHS (D-VHS), records digital high definition video onto a VHS form factor tape. D-VHS can record up to 4 hours of ATSC digital television in 720p or 1080i formats using the fastest record mode (equivalent to VHS-SP), and up to 49 hours of lower-definition video at slower speeds.

D9

Main article: Digital-S

There is also a JVC-designed component digital professional production format known as Digital-S, or officially under the name D9, that uses a VHS form factor tape and essentially the same mechanical tape handling techniques as an S-VHS recorder. This format is the least expensive format to support a Sel-Sync pre-read for video editing. This format competed with Sony's Digital Betacam in the professional and broadcast market, although in that area Sony's Betacam family ruled supreme, in contrast to the outcome of the VHS/Betamax domestic format war. It has now been superseded by high definition formats.

Accessories

Shortly after the introduction of the VHS format, VHS tape rewinders were developed. These devices served the sole purpose of rewinding VHS tapes. Proponents of the rewinders argued that the use of the rewind function on the standard VHS player would lead to wear and tear of the transport mechanism. The rewinder would rewind the tapes smoothly and also normally do so at a faster rate than the standard rewind function on VHS players. However some rewinder brands did have some frequent abrupt stops, which occasionally led to tape damage.

Some devices were marketed which allowed a personal computer to use a VHS recorder as a data backup device. The most notable of these was ArVid, widely used in Russia and CIS states. Similar systems were manufactured in the United States by Corvus and Alpha Microsystems, and in the UK by Backer from Danmere Ltd.

Signal standards

VHS can record and play back all varieties of analog television signals in existence at the time VHS was devised. However, a machine must be designed to record a given standard. Typically, a VHS machine can only handle signals using the same standard as the country it was sold in. This is because some parameters of analog broadcast TV are not applicable to VHS recordings, the number of VHS tape recording format variations is smaller than the number of broadcast TV signal variations—for example, analog TVs and VHS machines (except multistandard devices) are not interchangeable between the UK and Germany, but VHS tapes are. The following tape recording formats exist in conventional VHS (listed in the form of standard/lines/frames):

• SECAM/625/25 (SECAM, French variety)
• MESECAM/625/25 (most other SECAM countries, notably the former Soviet Union and Middle East)
• NTSC/525/30 (Most parts of Americas, Japan, South Korea)
• PAL/525/30 (i.e., PAL-M, Brazil)
• PAL/625/25 (most of Western Europe, Australia, New Zealand, many parts of Asia such as China and India, some parts of South America such as Argentina, Uruguay and the Falklands, and Africa)

Note that PAL/625/25 VCRs allow playback of SECAM (and MESECAM) tapes with a monochrome picture, and vice versa, as the line standard is the same. Since the 1990s dual and multi-standard VHS machines, able to handle a variety of VHS-supported video standards, became more common. For example, VHS machines sold in Australia and Europe could typically handle PAL, MESECAM for record and playback, and NTSC for playback only on suitable TVs. Dedicated multi-standard machines can usually handle all standards listed, and some high-end models could convert the content of a tape from one standard to another on the fly during playback by using a built-in standards converter.

S-VHS is only implemented as such in PAL/625/25 and NTSC/525/30; S-VHS machines sold in SECAM markets record internally in PAL, and convert between PAL and SECAM during recording and playback. S-VHS machines for the Brazilian market record in NTSC and convert between it and PAL-M.

A small number of VHS decks are able to decode closed captions on prerecorded video cassettes. A smaller number still are able, additionally, to record subtitles transmitted with world standard teletext signals (on pre-digital services), simultaneously with the associated program. S-VHS has a sufficient resolution to record teletext signals with relatively few errors.

Logo

The first VHS Logo

The VHS logo was commissioned by JVC and introduced with the JVC HR-3300 in 1976. It uses the Lee font, designed by Leo Weisz.

Uses in marketing

VHS was popular for long-form content, such as feature films or documentaries, as well as short-play content, such as music videos, in-store videos, teaching videos, distribution of lectures and talks, and demonstrations. VHS instruction tapes were sometimes included with various products and services, including exercise equipment, kitchen appliances, and computer software.

VHS vs. Betamax

Main article: Videotape format war

Size comparison between Betamax (top) and VHS (bottom) videocassettes.

VHS was the winner of a protracted and somewhat bitter format war during the late 1970s and early 1980s against Sony's Betamax format as well as other formats of the time.

Betamax was widely perceived at the time as the better format, as the cassette was smaller in size, and Betamax offered slightly better video quality than VHS – it had lower video noise, less luma-chroma crosstalk, and was marketed as providing pictures superior to those of VHS. However, the sticking point for both consumers and potential licensing partners of Betamax was the total recording time. To overcome the recording limitation, Beta II speed (two-hour mode, NTSC regions only) was released in order to compete with VHS's two-hour SP mode, thereby reducing Betamax's horizontal resolution to 240 lines (vs 250 lines). In turn, the extension of VHS to VHS HQ produced 250 lines (vs 240 lines), so that overall a typical Betamax/VHS user could expect virtually identical resolution. (Very high-end Betamax machines still supported recording in the Beta I mode and some in an even higher resolution Beta Is (Beta I Super HiBand) mode, but at a maximum single-cassette run time of 1:40 [with an L-830 cassette].)

Because Betamax was released more than a year before VHS, it held an early lead in the format war. However, by 1981, United States' Betamax sales had dipped to only 25-percent of all sales. There was debate between experts over the cause of Betamax's loss. Some, including Sony's founder Akio Morita, say that it was due to Sony's licensing strategy with other manufacturers, which consistently kept the overall cost for a unit higher than a VHS unit, and that JVC allowed other manufacturers to produce VHS units license-free, thereby keeping costs lower. Others say that VHS had better marketing, since the much larger electronics companies at the time (Matsushita, for example) supported VHS.

Decline

The VHS VCR was a mainstay in television-equipped American and European living rooms for more than 20 years from its introduction in 1977. The home television recording market, as well as the camcorder market, has since transitioned to digital recording on solid-state memory cards. The introduction of the DVD format to American consumers in March 1997 triggered the market share decline of VHS.

Though 94.5 million Americans still owned VHS format VCRs in 2005, market share continued to drop. Several retail chains in the United States and Europe announced they would stop selling VHS equipment throughout the mid-2000s. The last film to be released on the VHS format in the United States was Eragon in 2007. In 2008, Distribution Video Audio Inc., the last major American supplier of pre-recorded VHS tapes, shipped its final truckload of tapes to stores in America.

In the U.S., no major retailers stock VHS home-video releases any longer, focusing only on DVD and Blu-ray Disc technology. Additionally, all of the major Hollywood studios no longer issue releases on VHS. However, there have been a few exceptions. The House of the Devil was released on VHS in 2010 as an Amazon-exclusive deal, in keeping with the film's intent to mimic 1980s horror films. Also, the horror film V/H/S/2 was released as a combo in North America that included a VHS tape in addition to a Blu-ray and a DVD copy on September 24, 2013.

Modern usage

Despite the discontinuation of VHS in the United States, VHS recorders and blank tapes were still sold at stores in other developed countries prior to digital television transitions. As an acknowledgement of the continued usage of VHS, Panasonic announced the world's first dual deck VHS-Blu-ray player in 2009. The last standalone JVC VHS-only unit was produced on October 28, 2008. JVC, and other manufacturers, continued to make combination DVD+VHS units even after the decline of VHS.

Despite the decline in both VHS players and programming on VHS machines, they are still owned in some U.S. and Europe households. Those who still use or hold on to VHS do so for a number of reasons, including its alleged nostalgic value, its ease of use in recording, the fact that certain media still only exist in VHS format, their videos of personal events in their life are on VHS, or they are collectors of VHS releases. Expatriate communities in the United States also obtain video content from their native countries in VHS format.

Successors

VCD

See also: Video CD

The Video CD (VCD) was created in 1993, becoming an alternative medium for video, in a CD-sized disc. Though occasionally showing compression artifacts and color banding that are common discrepancies in digital media, the durability and longevity of a VCD depends on the production quality of the disc, and its handling. The data stored digitally on a VCD theoretically does not degrade (in the analog sense like tape). In the disc player, there is no physical contact made with either the data or label sides. And, when handled properly, a VCD will last a long time.

Since a VCD can only hold 74 minutes of video, a movie exceeding that mark has to be divided into two or more discs.

DVD

See also: DVD-Video

The DVD-Video format was introduced first, in 1996, in Japan, to the United States in March 1997 (test marketed) and mid-late 1998 in Europe and Australia.

Despite DVD's better quality (typical horizontal resolution of 480 versus 250 lines per picture height), and the availability of standalone DVD recorders, VHS is still used in home recording of video content. The commercial success of DVD recording and re-writing has been hindered by a number of factors including:

• A reputation for being temperamental and unreliable, as well as the risk of scratches and hairline cracks.
• Incompatibilities in playing discs recorded on a different manufacturer's machines to that of the original recording machine.
• Shorter recording time: VHS tape can record approximately twelve hours on a T-240/DF480 tape in EP, versus DVD which can record up to six hours on a single-layer disc.
• Compression artifacts: MPEG-2 video compression can result in visible artifacts such as macroblocking, mosquito noise and ringing which become accentuated in extended recording modes (more than three hours on a DVD-5 disc). Standard VHS will not suffer from any of these problems, all of which are characteristic of certain digital video compression systems (see Discrete cosine transform) but VHS will result in reduced luminance and chroma resolution, which makes the picture look horizontally blurred (resolution decreases further with LP and EP recording modes). VHS also adds considerable noise to both the luminance and chroma channels.

High-capacity digital recording technologies

See also: Digital video recorder

High-capacity digital recording systems are also gaining in popularity with home users. These types of systems come in several form factors:

• Hard disk–based set-top boxes
• Hard disk/optical disc combination set-top boxes
• Personal computer–based media center
• Portable media players with TV-out capability

Hard disk-based systems include TiVo as well as other digital video recorder (DVR) offerings. These types of systems provide users with a no-maintenance solution for capturing video content. Customers of subscriber-based TV generally receive electronic program guides, enabling one-touch setup of a recording schedule. Hard disk–based systems allow for many hours of recording without user-maintenance. For example, a 120 GB system recording at an extended recording rate (XP) of 10 Mbit/s MPEG-2 can record over 25 hours of video content.

Legacy

Often considered an important medium of film history, the influence of VHS on art and cinema was highlighted in a retrospective staged at the Museum of Arts and Design in 2013. In 2015 the Yale University Library collected nearly 3,000 horror and exploitation movies on VHS tapes, distributed from 1978 to 1985, calling them "the cultural id of an era."

External links

• HowStuffWorks: How VCRs work
• The 'Total Rewind' VCR museum covering the history of VHS and other vintage formats
• VHSCollector.com: Analog Video Cassette Archive A growing archive of commercially released video cassettes from their dawn to the present, and a guide to collecting.

"Teen" redirects here. For other uses, see Teen (disambiguation).

"Teenager" redirects here. For other uses, see Teenager (disambiguation).

"Adolescents" redirects here. For other uses, see Adolescents (disambiguation).

"Teenage girls" redirects here. For the EP by Love Kills, see Teenage Girls (EP).

Two adolescents listening to music using earphones

Adolescents of diverse backgrounds in Oslo

Adolescence (from Latin adolescere 'to grow up') is a transitional stage of physical and psychological development that generally occurs during the period from puberty to legal adulthood (age of majority). Adolescence is usually associated with the teenage years, but its physical, psychological or cultural expressions may begin earlier and end later. For example, puberty now typically begins during preadolescence, particularly in females. Physical growth (particularly in males), and cognitive development can extend into the early twenties. Thus age provides only a rough marker of adolescence, and scholars have found it difficult to agree upon a precise definition of adolescence.

A thorough understanding of adolescence in society depends on information from various perspectives, including psychology, biology, history, sociology, education, and anthropology. Within all of these perspectives, adolescence is viewed as a transitional period between childhood and adulthood, whose cultural purpose is the preparation of children for adult roles. It is a period of multiple transitions involving education, training, employment and unemployment, as well as transitions from one living circumstance to another.

The end of adolescence and the beginning of adulthood varies by country and by function. Furthermore, even within a single nation state or culture there can be different ages at which an individual is considered (chronologically and legally) mature enough for society to entrust them with certain privileges and responsibilities. Such milestones include driving a vehicle, having legal sexual relations, serving in the armed forces or on a jury, purchasing and drinking alcohol, voting, entering into contracts, finishing certain levels of education, and marriage. Adolescence is usually accompanied by an increased independence allowed by the parents or legal guardians, including less supervision as compared to preadolescence.

In studying adolescent development, adolescence can be defined biologically, as the physical transition marked by the onset of puberty and the termination of physical growth; cognitively, as changes in the ability to think abstractly and multi-dimensionally; or socially, as a period of preparation for adult roles. Major pubertal and biological changes include changes to the sex organs, height, weight, and muscle mass, as well as major changes in brain structure and organization. Cognitive advances encompass both increases in knowledge and in the ability to think abstractly and to reason more effectively. The study of adolescent development often involves interdisciplinary collaborations. For example, researchers in neuroscience or bio-behavioral health might focus on pubertal changes in brain structure and its effects on cognition or social relations. Sociologists interested in adolescence might focus on the acquisition of social roles (e.g., worker or romantic partner) and how this varies across cultures or social conditions. Developmental psychologists might focus on changes in relations with parents and peers as a function of school structure and pubertal status.

Biological development

Puberty in general

Main article: Puberty

Upper body of a teenage boy. The structure has changed to resemble an adult form.

Puberty is a period of several years in which rapid physical growth and psychological changes occur, culminating in sexual maturity. The average onset of puberty is at 10 or 11 for girls and age 11 or 12 for boys. Every person's individual timetable for puberty is influenced primarily by heredity, although environmental factors, such as diet and exercise, also exert some influences. These factors can also contribute to precocious and delayed puberty.

Some of the most significant parts of pubertal development involve distinctive physiological changes in individuals' height, weight, body composition, and circulatory and respiratory systems. These changes are largely influenced by hormonal activity. Hormones play an organizational role, priming the body to behave in a certain way once puberty begins, and an active role, referring to changes in hormones during adolescence that trigger behavioral and physical changes.

Puberty occurs through a long process and begins with a surge in hormone production, which in turn causes a number of physical changes. It is the stage of life characterized by the appearance and development of secondary sex characteristics (for example, a deeper voice and larger adam's apple in boys, and development of breasts and more curved and prominent hips in girls) and a strong shift in hormonal balance towards an adult state. This is triggered by the pituitary gland, which secretes a surge of hormonal agents into the blood stream, initiating a chain reaction to occur. The male and female gonads are subsequently activated, which puts them into a state of rapid growth and development; the triggered gonads now commence the mass production of the necessary chemicals. The testes primarily release testosterone, and the ovaries predominantly dispense estrogen. The production of these hormones increases gradually until sexual maturation is met. Some boys may develop gynecomastia due to an imbalance of sex hormones, tissue responsiveness or obesity.

Facial hair in males normally appears in a specific order during puberty: The first facial hair to appear tends to grow at the corners of the upper lip, typically between 14 and 17 years of age. It then spreads to form a moustache over the entire upper lip. This is followed by the appearance of hair on the upper part of the cheeks, and the area under the lower lip. The hair eventually spreads to the sides and lower border of the chin, and the rest of the lower face to form a full beard. As with most human biological processes, this specific order may vary among some individuals. Facial hair is often present in late adolescence, around ages 17 and 18, but may not appear until significantly later. Some men do not develop full facial hair for 10 years after puberty. Facial hair continues to get coarser, darker and thicker for another 2–4 years after puberty.

The major landmark of puberty for males is the first ejaculation, which occurs, on average, at age 13. For females, it is menarche, the onset of menstruation, which occurs, on average, between ages 12 and 13. The age of menarche is influenced by heredity, but a girl's diet and lifestyle contribute as well. Regardless of genes, a girl must have a certain proportion of body fat to attain menarche. Consequently, girls who have a high-fat diet and who are not physically active begin menstruating earlier, on average, than girls whose diet contains less fat and whose activities involve fat reducing exercise (e.g. ballet and gymnastics). Girls who experience malnutrition or are in societies in which children are expected to perform physical labor also begin menstruating at later ages.

The timing of puberty can have important psychological and social consequences. Early maturing boys are usually taller and stronger than their friends. They have the advantage in capturing the attention of potential partners and in becoming hand-picked for sports. Pubescent boys often tend to have a good body image, are more confident, secure, and more independent. Late maturing boys can be less confident because of poor body image when comparing themselves to already developed friends and peers. However, early puberty is not always positive for boys; early sexual maturation in boys can be accompanied by increased aggressiveness due to the surge of hormones that affect them. Because they appear older than their peers, pubescent boys may face increased social pressure to conform to adult norms; society may view them as more emotionally advanced, despite the fact that their cognitive and social development may lag behind their appearance. Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors.

For girls, early maturation can sometimes lead to increased self-consciousness, though a typical aspect in maturing females. Because of their bodies' developing in advance, pubescent girls can become more insecure and dependent. Consequently, girls that reach sexual maturation early are more likely than their peers to develop eating disorders (such as anorexia nervosa). Nearly half of all American high school girls' diets are to lose weight. In addition, girls may have to deal with sexual advances from older boys before they are emotionally and mentally mature. In addition to having earlier sexual experiences and more unwanted pregnancies than late maturing girls, early maturing girls are more exposed to alcohol and drug abuse. Those who have had such experiences tend to perform not as well in school as their "inexperienced" peers.

Girls have usually reached full physical development by ages 15–17, while boys usually complete puberty by ages 16–17. Any increase in height beyond the post-pubertal age is uncommon. Girls attain reproductive maturity about four years after the first physical changes of puberty appear. In contrast, boys accelerate more slowly but continue to grow for about six years after the first visible pubertal changes.

Approximate outline of development periods in child and teenager development. Adolescence is marked in red at top right.

Growth spurt

The adolescent growth spurt is a rapid increase in the individual's height and weight during puberty resulting from the simultaneous release of growth hormones, thyroid hormones, and androgens. Males experience their growth spurt about two years later, on average, than females. During their peak height velocity (the time of most rapid growth), adolescents grow at a growth rate nearly identical to that of a toddler—about 4 inches (10.3 cm) a year for males and 3.5 inches (9 cm) for females. In addition to changes in height, adolescents also experience a significant increase in weight (Marshall, 1978). The weight gained during adolescence constitutes nearly half of one's adult body weight. Teenage and early adult males may continue to gain natural muscle growth even after puberty.

The accelerated growth in different body parts happens at different times, but for all adolescents it has a fairly regular sequence. The first places to grow are the extremities—the head, hands and feet—followed by the arms and legs, then the torso and shoulders. This non-uniform growth is one reason why an adolescent body may seem out of proportion.

During puberty, bones become harder and more brittle. At the conclusion of puberty, the ends of the long bones close during the process called epiphysis. There can be ethnic differences in these skeletal changes. For example, in the United States of America, bone density increases significantly more among black than white adolescents, which might account for decreased likelihood of black women developing osteoporosis and having fewer bone fractures there.

Another set of significant physical changes during puberty happen in bodily distribution of fat and muscle. This process is different for females and males. Before puberty, there are nearly no sex differences in fat and muscle distribution; during puberty, boys grow muscle much faster than girls, although both sexes experience rapid muscle development. In contrast, though both sexes experience an increase in body fat, the increase is much more significant for girls. Frequently, the increase in fat for girls happens in their years just before puberty. The ratio between muscle and fat among post-pubertal boys is around three to one, while for girls it is about five to four. This may help explain sex differences in athletic performance.

Pubertal development also affects circulatory and respiratory systems as an adolescents' heart and lungs increase in both size and capacity. These changes lead to increased strength and tolerance for exercise. Sex differences are apparent as males tend to develop "larger hearts and lungs, higher systolic blood pressure, a lower resting heart rate, a greater capacity for carrying oxygen to the blood, a greater power for neutralizing the chemical products of muscular exercise, higher blood hemoglobin and more red blood cells".

Despite some genetic sex differences, environmental factors play a large role in biological changes during adolescence. For example, girls tend to reduce their physical activity in preadolescence and may receive inadequate nutrition from diets that often lack important nutrients, such as iron. These environmental influences in turn affect female physical development.

Reproduction-related changes

Primary sex characteristics are those directly related to the sex organs. In males, the first stages of puberty involve growth of the testes and scrotum, followed by growth of the penis. At the time that the penis develops, the seminal vesicles, the prostate, and the bulbourethral gland also enlarge and develop. The first ejaculation of seminal fluid generally occurs about one year after the beginning of accelerated penis growth, although this is often determined culturally rather than biologically, since for many boys first ejaculation occurs as a result of masturbation. Boys are generally fertile before they have an adult appearance.

In females, changes in the primary sex characteristics involve growth of the uterus, vagina, and other aspects of the reproductive system. Menarche, the beginning of menstruation, is a relatively late development which follows a long series of hormonal changes. Generally, a girl is not fully fertile until several years after menarche, as regular ovulation follows menarche by about two years. Unlike males, therefore, females usually appear physically mature before they are capable of becoming pregnant.

Changes in secondary sex characteristics include every change that is not directly related to sexual reproduction. In males, these changes involve appearance of pubic, facial, and body hair, deepening of the voice, roughening of the skin around the upper arms and thighs, and increased development of the sweat glands. In females, secondary sex changes involve elevation of the breasts, widening of the hips, development of pubic and underarm hair, widening of the areolae, and elevation of the nipples. The changes in secondary sex characteristics that take place during puberty are often referred to in terms of five Tanner stages, named after the British pediatrician who devised the categorization system.

Changes in the brain

The human brain is not fully developed by the time a person reaches puberty. Between the ages of 10 and 25, the brain undergoes changes that have important implications for behavior (see Cognitive development below). The brain reaches 90% of its adult size by the time a person is six years of age. Thus, the brain does not grow in size much during adolescence. However, the creases in the brain continue to become more complex until the late teens. The biggest changes in the folds of the brain during this time occur in the parts of the cortex that process cognitive and emotional information.

Over the course of adolescence, the amount of white matter in the brain increases linearly, while the amount of grey matter in the brain follows an inverted-U pattern. Through a process called synaptic pruning, unnecessary neuronal connections in the brain are eliminated and the amount of grey matter is pared down. However, this does not mean that the brain loses functionality; rather, it becomes more efficient due to increased myelination (insulation of axons) and the reduction of unused pathways.

The first areas of the brain to be pruned are those involving primary functions, such as motor and sensory areas. The areas of the brain involved in more complex processes lose matter later in development. These include the lateral and prefrontal cortices, among other regions. Some of the most developmentally significant changes in the brain occur in the prefrontal cortex, which is involved in decision making and cognitive control, as well as other higher cognitive functions. During adolescence, myelination and synaptic pruning in the prefrontal cortex increases, improving the efficiency of information processing, and neural connections between the prefrontal cortex and other regions of the brain are strengthened. This leads to better evaluation of risks and rewards, as well as improved control over impulses. Specifically, developments in the dorsolateral prefrontal cortex are important for controlling impulses and planning ahead, while development in the ventromedial prefrontal cortex is important for decision making. Changes in the orbitofrontal cortex are important for evaluating rewards and risks.

Three neurotransmitters that play important roles in adolescent brain development are glutamate, dopamine and serotonin. Glutamate is an excitatory neurotransmitter. During the synaptic pruning that occurs during adolescence, most of the neural connections that are pruned contain receptors for glutamate or other excitatory neurotransmitters. Because of this, by early adulthood the synaptic balance in the brain is more inhibitory than excitatory.

Dopamine is associated with pleasure and attuning to the environment during decision-making. During adolescence, dopamine levels in the limbic system increase and input of dopamine to the prefrontal cortex increases. The balance of excitatory to inhibitory neurotransmitters and increased dopamine activity in adolescence may have implications for adolescent risk-taking and vulnerability to boredom (see Cognitive development below).

Serotonin is a neuromodulator involved in regulation of mood and behavior. Development in the limbic system plays an important role in determining rewards and punishments and processing emotional experience and social information. Changes in the levels of the neurotransmitters dopamine and serotonin in the limbic system make adolescents more emotional and more responsive to rewards and stress. The corresponding increase in emotional variability also can increase adolescents' vulnerability. The effect of serotonin is not limited to the limbic system: Several serotonin receptors have their gene expression change dramatically during adolescence, particularly in the human frontal and prefrontal cortex .

Cognitive development

Adolescence is also a time for rapid cognitive development. Piaget describes adolescence as the stage of life in which the individual's thoughts start taking more of an abstract form and the egocentric thoughts decrease. This allows the individual to think and reason in a wider perspective. A combination of behavioural and fMRI studies have demonstrated development of executive functions, that is, cognitive skills that enable the control and coordination of thoughts and behaviour, which are generally associated with the prefrontal cortex. The thoughts, ideas and concepts developed at this period of life greatly influence one's future life, playing a major role in character and personality formation.

Biological changes in brain structure and connectivity within the brain interact with increased experience, knowledge, and changing social demands to produce rapid cognitive growth (see Changes in the brain above). The age at which particular changes take place varies between individuals, but the changes discussed below begin at puberty or shortly after that and some skills continue to develop as the adolescent ages.

Theoretical perspectives

There are at least two major approaches to understanding cognitive change during adolescence. One is the constructivist view of cognitive development. Based on the work of Piaget, it takes a quantitative, state-theory approach, hypothesizing that adolescents' cognitive improvement is relatively sudden and drastic. The second is the information-processing perspective, which derives from the study of artificial intelligence and attempts to explain cognitive development in terms of the growth of specific components of the thinking process.

Improvements in cognitive ability

By the time individuals have reached age 15 or so, their basic thinking abilities are comparable to those of adults. These improvements occur in five areas during adolescence:

1. Attention. Improvements are seen in selective attention, the process by which one focuses on one stimulus while tuning out another. Divided attention, the ability to pay attention to two or more stimuli at the same time, also improves.
2. Memory. Improvements are seen in both working memory and long-term memory.
3. Processing speed. Adolescents think more quickly than children. Processing speed improves sharply between age five and middle adolescence; it then begins to level off at age 15 and does not appear to change between late adolescence and adulthood.
4. Organization. Adolescents are more aware of their thought processes and can use mnemonic devices and other strategies to think more efficiently.
5. Metacognition.

Studies since 2005 indicate that the brain is not fully formed until the early twenties.

Hypothetical and abstract thinking

Adolescents' thinking is less bound to concrete events than that of children: they can contemplate possibilities outside the realm of what currently exists. One manifestation of the adolescent's increased facility with thinking about possibilities is the improvement of skill in deductive reasoning, which leads to the development of hypothetical thinking. This provides the ability to plan ahead, see the future consequences of an action and to provide alternative explanations of events. It also makes adolescents more skilled debaters, as they can reason against a friend's or parent's assumptions. Adolescents also develop a more sophisticated understanding of probability.

The appearance of more systematic, abstract thinking is another notable aspect of cognitive development during adolescence. For example, adolescents find it easier than children to comprehend the sorts of higher-order abstract logic inherent in puns, proverbs, metaphors, and analogies. Their increased facility permits them to appreciate the ways in which language can be used to convey multiple messages, such as satire, metaphor, and sarcasm. (Children younger than age nine often cannot comprehend sarcasm at all.) This also permits the application of advanced reasoning and logical processes to social and ideological matters such as interpersonal relationships, politics, philosophy, religion, morality, friendship, faith, fairness, and honesty.

Metacognition

A third gain in cognitive ability involves thinking about thinking itself, a process referred to as metacognition. It often involves monitoring one's own cognitive activity during the thinking process. Adolescents' improvements in knowledge of their own thinking patterns lead to better self-control and more effective studying. It is also relevant in social cognition, resulting in increased introspection, self-consciousness, and intellectualization (in the sense of thought about one's own thoughts, rather than the Freudian definition as a defense mechanism). Adolescents are much better able than children to understand that people do not have complete control over their mental activity. Being able to introspect may lead to two forms of adolescent egocentrism, which results in two distinct problems in thinking: the imaginary audience and the personal fable. These likely peak at age fifteen, along with self-consciousness in general.

Related to metacognition and abstract thought, perspective-taking involves a more sophisticated theory of mind. Adolescents reach a stage of social perspective-taking in which they can understand how the thoughts or actions of one person can influence those of another person, even if they personally are not involved.

Relativistic thinking

Compared to children, adolescents are more likely to question others' assertions, and less likely to accept facts as absolute truths. Through experience outside the family circle, they learn that rules they were taught as absolute are in fact relativistic. They begin to differentiate between rules instituted out of common sense—not touching a hot stove—and those that are based on culturally-relative standards (codes of etiquette, not dating until a certain age), a delineation that younger children do not make. This can lead to a period of questioning authority in all domains.

Wisdom

Wisdom, or the capacity for insight and judgment that is developed through experience, increases between the ages of fourteen and twenty-five, then levels off. Thus, it is during the adolescence-adulthood transition that individuals acquire the type of wisdom that is associated with age. Wisdom is not the same as intelligence: adolescents do not improve substantially on IQ tests since their scores are relative to others in their same age group, and relative standing usually does not change—everyone matures at approximately the same rate in this way.

Risk-taking

Because most injuries sustained by adolescents are related to risky behavior (car crashes, alcohol, unprotected sex), a great deal of research has been done on the cognitive and emotional processes underlying adolescent risk-taking. In addressing this question, it is important to distinguish whether adolescents are more likely to engage in risky behaviors (prevalence), whether they make risk-related decisions similarly or differently than adults (cognitive processing perspective), or whether they use the same processes but value different things and thus arrive at different conclusions. The behavioral decision-making theory proposes that adolescents and adults both weigh the potential rewards and consequences of an action. However, research has shown that adolescents seem to give more weight to rewards, particularly social rewards, than do adults.

Research seems to favor the hypothesis that adolescents and adults think about risk in similar ways, but hold different values and thus come to different conclusions. Some have argued that there may be evolutionary benefits to an increased propensity for risk-taking in adolescence. For example, without a willingness to take risks, teenagers would not have the motivation or confidence necessary to leave their family of origin. In addition, from a population perspective, there is an advantage to having a group of individuals willing to take more risks and try new methods, counterbalancing the more conservative elements more typical of the received knowledge held by older adults. Risktaking may also have reproductive advantages: adolescents have a newfound priority in sexual attraction and dating, and risk-taking is required to impress potential mates. Research also indicates that baseline sensation seeking may affect risk-taking behavior throughout the lifespan.

Given the potential consequences, engaging in sexual behavior is somewhat risky, particularly for adolescents. Having unprotected sex, using poor birth control methods (e.g. withdrawal), having multiple sexual partners, and poor communication are some aspects of sexual behavior that increase individual and/or social risk. Some qualities of adolescents' lives that are often correlated with risky sexual behavior include higher rates of experienced abuse, lower rates of parental support and monitoring.

Inhibition

Related to their increased tendency for risk-taking, adolescents show impaired behavioral inhibition, including deficits in extinction learning. This has important implications for engaging in risky behavior such as unsafe sex or illicit drug use, as adolescents are less likely to inhibit actions that may have negative outcomes in the future. This phenomenon also has consequences for behavioral treatments based on the principle of extinction, such as cue exposure therapy for anxiety or drug addiction. It has been suggested that impaired inhibition, specifically extinction, may help to explain adolescent propensity to relapse to drug-seeking even following behavioral treatment for addiction.

Psychological development

G. Stanley Hall

The formal study of adolescent psychology began with the publication of G. Stanley Hall's "Adolescence in 1904." Hall, who was the first president of the American Psychological Association, viewed adolescence primarily as a time of internal turmoil and upheaval (sturm und drang). This understanding of youth was based on two then new ways of understanding human behavior: Darwin's evolutionary theory and Freud's psychodynamic theory. He believed that adolescence was a representation of our human ancestors' phylogenetic shift from being primitive to being civilized. Hall's assertions stood relatively uncontested until the 1950s when psychologists such as Erik Erikson and Anna Freud started to formulate their theories about adolescence. Freud believed that the psychological disturbances associated with youth were biologically based and culturally universal while Erikson focused on the dichotomy between identity formation and role fulfillment. Even with their different theories, these three psychologists agreed that adolescence was inherently a time of disturbance and psychological confusion. The less turbulent aspects of adolescence, such as peer relations and cultural influence, were left largely ignored until the 1980s. From the '50s until the '80s, the focus of the field was mainly on describing patterns of behavior as opposed to explaining them.

Jean Macfarlane founded the University of California, Berkeley's Institute of Human Development, formerly called the Institute of Child Welfare, in 1927. The Institute was instrumental in initiating studies of healthy development, in contrast to previous work that had been dominated by theories based on pathological personalities. The studies looked at human development during the Great Depression and World War II, unique historical circumstances under which a generation of children grew up. The Oakland Growth Study, initiated by Harold Jones and Herbert Stolz in 1931, aimed to study the physical, intellectual, and social development of children in the Oakland area. Data collection began in 1932 and continued until 1981, allowing the researchers to gather longitudinal data on the individuals that extended past adolescence into adulthood. Jean Macfarlane launched the Berkeley Guidance Study, which examined the development of children in terms of their socioeconomic and family backgrounds. These studies provided the background for Glen Elder in the 1960s, to propose a life-course perspective of adolescent development. Elder formulated several descriptive principles of adolescent development. The principle of historical time and place states that an individual's development is shaped by the period and location in which they grow up. The principle of the importance of timing in one's life refers to the different impact that life events have on development based on when in one's life they occur. The idea of linked lives states that one's development is shaped by the interconnected network of relationships of which one is a part; and the principle of human agency asserts that one's life course is constructed via the choices and actions of an individual within the context of their historical period and social network.

In 1984, the Society for Research on Adolescence (SRA) became the first official organization dedicated to the study of adolescent psychology. Some of the issues first addressed by this group include: the nature versus nurture debate as it pertains to adolescence; understanding the interactions between adolescents and their environment; and considering culture, social groups, and historical context when interpreting adolescent behavior.

Evolutionary biologists like Jeremy Griffith have drawn parallels between adolescent psychology and the developmental evolution of modern humans from hominid ancestors as a manifestation of ontogeny recapitulating phylogeny.

Social development

Identity development

Identity development is a stage in the adolescent life cycle. For most, the search for identity begins in the adolescent years. During these years, adolescents are more open to 'trying on' different behaviours and appearances to discover who they are. In an attempt to find their identity and discover who they are, adolescents are liklely to cycle through a number of identities to find one that suits them best. Developing and maintaining identity (in adolescent years) is a difficult task due to multiple factors such as family life, environment, and social status. Empirical studies suggest that this process might be more accurately described as identity development, rather than formation, but confirms a normative process of change in both content and structure of one's thoughts about the self. The two main aspects of identity development are self-clarity and self-esteem. Since choices made during adolescent years can influence later life, high levels of self-awareness and self-control during mid-adolescence will lead to better decisions during the transition to adulthood. Researchers have used three general approaches to understanding identity development: self-concept, sense of identity, and self-esteem. The years of adolescence create a more conscientious group of young adults. Adolescents pay close attention and give more time and effort to their appearance as their body goes through changes. Unlike children, teens put forth an effort to look presentable (1991). The environment in which an adolescent grows up also plays an important role in their identity development. Studies done by the American Psychological Association have shown that adolescents with a less privileged upbringing have a more difficult time developing their identity.

Self-concept

See also: Self-concept

The idea of self-concept is known as the ability of a person to have opinions and beliefs that are defined confidently, consistent and stable. Early in adolescence, cognitive developments result in greater self-awareness, greater awareness of others and their thoughts and judgments, the ability to think about abstract, future possibilities, and the ability to consider multiple possibilities at once. As a result, adolescents experience a significant shift from the simple, concrete, and global self-descriptions typical of young children; as children, they defined themselves by physical traits whereas as adolescents, they define themselves based on their values, thoughts, and opinions.

Adolescents can conceptualize multiple "possible selves" that they could become and long-term possibilities and consequences of their choices. Exploring these possibilities may result in abrupt changes in self-presentation as the adolescent chooses or rejects qualities and behaviors, trying to guide the actual self toward the ideal self (who the adolescent wishes to be) and away from the feared self (who the adolescent does not want to be). For many, these distinctions are uncomfortable, but they also appear to motivate achievement through behavior consistent with the ideal and distinct from the feared possible selves.

Further distinctions in self-concept, called "differentiation," occur as the adolescent recognizes the contextual influences on their own behavior and the perceptions of others, and begin to qualify their traits when asked to describe themselves. Differentiation appears fully developed by mid-adolescence. Peaking in the 7th-9th grades, the personality traits adolescents use to describe themselves refer to specific contexts, and therefore may contradict one another. The recognition of inconsistent content in the self-concept is a common source of distress in these years (see Cognitive dissonance), but this distress may benefit adolescents by encouraging structural development.

Sense of identity

Egocentrism in adolescents forms a self-conscious desire to feel important in their peer groups and enjoy social acceptance. Unlike the conflicting aspects of self-concept, identity represents a coherent sense of self stable across circumstances and including past experiences and future goals. Everyone has a self-concept, whereas Erik Erikson argued that not everyone fully achieves identity. Erikson's theory of stages of development includes the identity crisis in which adolescents must explore different possibilities and integrate different parts of themselves before committing to their beliefs. He described the resolution of this process as a stage of "identity achievement" but also stressed that the identity challenge "is never fully resolved once and for all at one point in time". Adolescents begin by defining themselves based on their crowd membership. "Clothes help teens explore new identities, separate from parents, and bond with peers." Fashion has played a major role when it comes to teenagers "finding their selves"; Fashion is always evolving, which corresponds with the evolution of change in the personality of teenagers. Adolescents attempt to define their identity by consciously styling themselves in different manners to find what best suits them. Trial and error in matching both their perceived image and the image others respond to and see, allows for the adolescent to grasp an understanding of who they are Just as fashion is evolving to influence adolescents so is the media. "Modern life takes place amidst a never-ending barrage of flesh on screens, pages, and billboards." This barrage consciously or subconsciously registers into the mind causing issues with self-image a factor that contributes to an adolescence sense of identity. Researcher James Marcia developed the current method for testing an individual's progress along these stages. His questions are divided into three categories: occupation, ideology, and interpersonal relationships. Answers are scored based on extent to which the individual has explored and the degree to which he has made commitments. The result is classification of the individual into a) identity diffusion in which all children begin, b) Identity Foreclosure in which commitments are made without the exploration of alternatives, c) Moratorium, or the process of exploration, or d) Identity Achievement in which Moratorium has occurred and resulted in commitments.

Research since reveals self-examination beginning early in adolescence, but identity achievement rarely occurring before age 18. The freshman year of college influences identity development significantly, but may actually prolong psychosocial moratorium by encouraging reexamination of previous commitments and further exploration of alternate possibilities without encouraging resolution. For the most part, evidence has supported Erikson's stages: each correlates with the personality traits he originally predicted. Studies also confirm the impermanence of the stages; there is no final endpoint in identity development.

Environment and identity

An adolescent's environment plays a huge role in their identity development. While most adolescent studies are conducted on white, middle class children, studies show that the more privileged upbringing people have, the more successfully they develop their identity. The forming of an adolescent's identity is a crucial time in their life. It has been recently found that demographic patterns suggest that the transition to adulthood is now occurring over a longer span of years than was the case during the middle of the 20th century. Accordingly, youth, a period that spans late adolescence and early adulthood, has become a more prominent stage of the life course. This therefore has caused various factors to become important during this development. So many factors contribute to the developing social identity of an adolescent from commitment, to coping devices, to social media. All of these factors are affected by the environment an adolescent grows up in. A child from a more privileged upbringing is exposed to more opportunities and better situations in general. An adolescent from an inner city or a crime-driven neighborhood is more likely to be exposed to an environment that can be detrimental to their development. Adolescence is a sensitive period in the development process, and exposure to the wrong things at that time can have a major effect on future decisions. While children that grow up in nice suburban communities are not exposed to bad environments they are more likely to participate in activities that can benefit their identity and contribute to a more successful identity development.

Sexual orientation and identity

Sexual orientation has been defined as "an erotic inclination toward people of one or more genders, most often described as sexual or erotic attractions". In recent years, psychologists have sought to understand how sexual orientation develops during adolescence. Some theorists believe that there are many different possible developmental paths one could take, and that the specific path an individual follows may be determined by their sex, orientation, and when they reached the onset of puberty.

In 1989, Troiden proposed a four-stage model for the development of homosexual sexual identity. The first stage, known as sensitization, usually starts in childhood, and is marked by the child's becoming aware of same-sex attractions. The second stage, identity confusion, tends to occur a few years later. In this stage, the youth is overwhelmed by feelings of inner turmoil regarding their sexual orientation, and begins to engage sexual experiences with same-sex partners. In the third stage of identity assumption, which usually takes place a few years after the adolescent has left home, adolescents begin to come out to their family and close friends, and assumes a self-definition as gay, lesbian, or bisexual. In the final stage, known as commitment, the young adult adopts their sexual identity as a lifestyle. Therefore, this model estimates that the process of coming out begins in childhood, and continues through the early to mid 20s. This model has been contested, and alternate ideas have been explored in recent years.

In terms of sexual identity, adolescence is when most gay/lesbian and transgender adolescents begin to recognize and make sense of their feelings. Many adolescents may choose to come out during this period of their life once an identity has been formed; many others may go through a period of questioning or denial, which can include experimentation with both homosexual and heterosexual experiences. A study of 194 lesbian, gay, and bisexual youths under the age of 21 found that having an awareness of one's sexual orientation occurred, on average, around age 10, but the process of coming out to peers and adults occurred around age 16 and 17, respectively. Coming to terms with and creating a positive LGBT identity can be difficult for some youth for a variety of reasons. Peer pressure is a large factor when youth who are questioning their sexuality or gender identity are surrounded by heteronormative peers and can cause great distress due to a feeling of being different from everyone else. While coming out can also foster better psychological adjustment, the risks associated are real. Indeed, coming out in the midst of a heteronormative peer environment often comes with the risk of ostracism, hurtful jokes, and even violence. Because of this, statistically the suicide rate amongst LGBT adolescents is up to four times higher than that of their heterosexual peers due to bullying and rejection from peers or family members.

Self-esteem

The final major aspect of identity formation is self-esteem. Self-esteem is defined as one's thoughts and feelings about one's self-concept and identity. Most theories on self-esteem state that there is a grand desire, across all genders and ages, to maintain, protect and enhance their self-esteem. Contrary to popular belief, there is no empirical evidence for a significant drop in self-esteem over the course of adolescence. "Barometric self-esteem" fluctuates rapidly and can cause severe distress and anxiety, but baseline self-esteem remains highly stable across adolescence. The validity of global self-esteem scales has been questioned, and many suggest that more specific scales might reveal more about the adolescent experience. Girls are most likely to enjoy high self-esteem when engaged in supportive relationships with friends, the most important function of friendship to them is having someone who can provide social and moral support. When they fail to win friends' approval or couldn't find someone with whom to share common activities and common interests, in these cases, girls suffer from low self-esteem. In contrast, boys are more concerned with establishing and asserting their independence and defining their relation to authority. As such, they are more likely to derive high self-esteem from their ability to successfully influence their friends; on the other hand, the lack of romantic competence, for example, failure to win or maintain the affection of the opposite or same-sex (depending on sexual orientation), is the major contributor to low self-esteem in adolescent boys. Due to the fact that both men and women happen to have a low self-esteem after ending a romantic relationship, they are prone to other symptoms that is caused by this state. Depression and hopelessness are only two of the various symptoms and it is said that women are twice as likely to experience depression and men are three to four times more likely to commit suicide (Mearns, 1991; Ustun & Sartorius, 1995).

Relationships

In general

The relationships adolescents have with their peers, family, and members of their social sphere play a vital role in the social development of an adolescent. As an adolescent's social sphere develops rapidly as they distinguish the differences between friends and acquaintances, they often become heavily emotionally invested in friends. This is not harmful; however, if these friends expose an individual to potentially harmful situations, this is an aspect of peer pressure. Adolescence is a critical period in social development because adolescents can be easily influenced by the people they develop close relationships with. This is the first time individuals can truly make their own decisions, which also makes this a sensitive period. Relationships are vital in the social development of an adolescent due to the extreme influence peers can have over an individual. These relationships become significant because they begin to help the adolescent understand the concept of personalities, how they form and why a person has that specific type of personality. "The use of psychological comparisons could serve both as an index of the growth of an implicit personality theory and as a component process accounting for its creation. In other words, by comparing one person's personality characteristics to another's, we would be setting up the framework for creating a general theory of personality (and, ... such a theory would serve as a useful framework for coming to understand specific persons)." This can be likened to the use of social comparison in developing one's identity and self-concept, which includes ones personality, and underscores the importance of communication, and thus relationships, in one's development. In social comparison we use reference groups, with respect to both psychological and identity development. These reference groups are the peers of adolescents. This means that who the teen chooses/accepts as their friends and who they communicate with on a frequent basis often makes up their reference groups and can therefore have a huge impact on who they become. Research shows that relationships have the largest affect over the social development of an individual.

Family

See also: Depression in childhood and adolescence and Sibling relationship

Teenage sisters

Adolescence marks a rapid change in one's role within a family. Young children tend to assert themselves forcefully, but are unable to demonstrate much influence over family decisions until early adolescence, when they are increasingly viewed by parents as equals. The adolescent faces the task of increasing independence while preserving a caring relationship with his or her parents. When children go through puberty, there is often a significant increase in parent–child conflict and a less cohesive familial bond. Arguments often concern minor issues of control, such as curfew, acceptable clothing, and the adolescent's right to privacy, which adolescents may have previously viewed as issues over which their parents had complete authority. Parent-adolescent disagreement also increases as friends demonstrate a greater impact on one another, new influences on the adolescent that may be in opposition to parents' values. Social media has also played an increasing role in adolescent and parent disagreements. While parents never had to worry about the threats of social media in the past, it has become a dangerous place for children. While adolescents strive for their freedoms, the unknowns to parents of what their child is doing on social media sites is a challenging subject, due to the increasing amount of predators on social media sites. Many parents have very little knowledge of social networking sites in the first place and this further increases their mistrust. An important challenge for the parent–adolescent relationship is to understand how to enhance the opportunities of online communication while managing its risks. Although conflicts between children and parents increase during adolescence, these are just relatively minor issues. Regarding their important life issues, most adolescents still share the same attitudes and values as their parents.

During childhood, siblings are a source of conflict and frustration as well as a support system. Adolescence may affect this relationship differently, depending on sibling gender. In same-sex sibling pairs, intimacy increases during early adolescence, then remains stable. Mixed-sex siblings pairs act differently; siblings drift apart during early adolescent years, but experience an increase in intimacy starting at middle adolescence. Sibling interactions are children's first relational experiences, the ones that shape their social and self-understanding for life. Sustaining positive sibling relations can assist adolescents in a number of ways. Siblings are able to act as peers, and may increase one another's sociability and feelings of self-worth. Older siblings can give guidance to younger siblings, although the impact of this can be either positive or negative depending on the activity of the older sibling.

A potential important influence on adolescence is change of the family dynamic, specifically divorce. With the divorce rate up to about 50%, divorce is common and adds to the already great amount of change in adolescence. Custody disputes soon after a divorce often reflect a playing out of control battles and ambivalence between parents. Divorce usually results in less contact between the adolescent and their noncustodial parent. In extreme cases of instability and abuse in homes, divorce can have a positive effect on families due to less conflict in the home. However, most research suggests a negative effect on adolescence as well as later development. A recent study found that, compared with peers who grow up in stable post-divorce families, children of divorce who experience additional family transitions during late adolescence, make less progress in their math and social studies performance over time. Another recent study put forth a new theory entitled the adolescent epistemological trauma theory, which posited that traumatic life events such as parental divorce during the formative period of late adolescence portend lifelong effects on adult conflict behavior that can be mitigated by effective behavioral assessment and training. A parental divorce during childhood or adolescence continues to have a negative effect when a person is in his or her twenties and early thirties. These negative effects include romantic relationships and conflict style, meaning as adults, they are more likely to use the styles of avoidance and competing in conflict management.

Despite changing family roles during adolescence, the home environment and parents are still important for the behaviors and choices of adolescents. Adolescents who have a good relationship with their parents are less likely to engage in various risk behaviors, such as smoking, drinking, fighting, and/or unprotected sexual intercourse. In addition, parents influence the education of adolescence. A study conducted by Adalbjarnardottir and Blondal (2009) showed that adolescents at the age of 14 who identify their parents as authoritative figures are more likely to complete secondary education by the age of 22—as support and encouragement from an authoritative parent motivates the adolescence to complete schooling to avoid disappointing that parent.

Peers

Peer groups are essential to social and general development. Communication with peers increases significantly during adolescence and peer relationships become more intense than in other stages and more influential to the teen, affecting both the decisions and choices being made. High quality friendships may enhance children's development regardless of the characteristics of those friends. As children begin to bond with various people and create friendships, it later helps them when they are adolescent and sets up the framework for adolescence and peer groups. Peer groups are especially important during adolescence, a period of development characterized by a dramatic increase in time spent with peers and a decrease in adult supervision. Adolescents also associate with friends of the opposite sex much more than in childhood and tend to identify with larger groups of peers based on shared characteristics. It is also common for adolescents to use friends as coping devices in different situations. A three-factor structure of dealing with friends including avoidance, mastery, and nonchalance has shown that adolescents use friends as coping devices with social stresses.

Communication within peer groups allows adolescents to explore their feelings and identity as well as develop and evaluate their social skills. Peer groups offer members the opportunity to develop social skills such as empathy, sharing, and leadership. Adolescents choose peer groups based on characteristics similarly found in themselves. By utilizing these relationships, adolescents become more accepting of who they are becoming. Group norms and values are incorporated into an adolescent's own self-concept. Through developing new communication skills and reflecting upon those of their peers, as well as self-opinions and values, an adolescent can share and express emotions and other concerns without fear of rejection or judgment. Peer groups can have positive influences on an individual, such as on academic motivation and performance. However, while peers may facilitate social development for one another they may also hinder it. Peers can have negative influences, such as encouraging experimentation with drugs, drinking, vandalism, and stealing through peer pressure. Susceptibility to peer pressure increases during early adolescence, peaks around age 14, and declines thereafter. Further evidence of peers hindering social development has been found in Spanish teenagers, where emotional (rather than solution-based) reactions to problems and emotional instability have been linked with physical aggression against peers. Both physical and relational aggression are linked to a vast number of enduring psychological difficulties, especially depression, as is social rejection. Because of this, bullied adolescents often develop problems that lead to further victimization. Bullied adolescents are more likely to both continue to be bullied and to bully others in the future. However, this relationship is less stable in cases of cyberbullying, a relatively new issue among adolescents.

Teens using online communication

Adolescents tend to associate with "cliques" on a small scale and "crowds" on a larger scale. During early adolescence, adolescents often associate in cliques, exclusive, single-sex groups of peers with whom they are particularly close. Despite the common notion that cliques are an inherently negative influence, they may help adolescents become socially acclimated and form a stronger sense of identity. Within a clique of highly athletic male-peers, for example, the clique may create a stronger sense of fidelity and competition. Cliques also have become somewhat a "collective parent", i.e. telling the adolescents what to do and not to do. Towards late adolescence, cliques often merge into mixed-sex groups as teenagers begin romantically engaging with one another. These small friend groups then break down further as socialization becomes more couple-oriented. On a larger scale, adolescents often associate with crowds, groups of individuals who share a common interest or activity. Often, crowd identities may be the basis for stereotyping young people, such as jocks or nerds. In large, multi-ethnic high schools, there are often ethnically determined crowds. While crowds are very influential during early and middle adolescence, they lose salience during high school as students identify more individually.

An important aspect of communication is the channel used. Channel, in this respect, refers to the form of communication, be it face-to-face, email, text message, phone or other. Teens are heavy users of newer forms of communication such as text message and social-networking websites such as Facebook, especially when communicating with peers. Adolescents use online technology to experiment with emerging identities and to broaden their peer groups, such as increasing the amount of friends acquired on Facebook and other social media sites. Some adolescents use these newer channels to enhance relationships with peers however there can be negative uses as well such as cyberbullying, as mentioned previously, and negative impacts on the family.

Romance and sexual activity

Main article: Adolescent sexuality

See also: Adolescent sexuality in the United States

Romantic relationships tend to increase in prevalence throughout adolescence. By age 15, 53% of adolescents have had a romantic relationship that lasted at least one month over the course of the previous 18 months. In a 2008 study conducted by YouGov for Channel 4, 20% of 14−17-year-olds surveyed revealed that they had their first sexual experience at 13 or under in the United Kingdom. A 2002 American study found that those aged 15–44 reported that the average age of first sexual intercourse was 17.0 for males and 17.3 for females. The typical duration of relationships increases throughout the teenage years as well. This constant increase in the likelihood of a long-term relationship can be explained by sexual maturation and the development of cognitive skills necessary to maintain a romantic bond (e.g. caregiving, appropriate attachment), although these skills are not strongly developed until late adolescence. Long-term relationships allow adolescents to gain the skills necessary for high-quality relationships later in life and develop feelings of self-worth. Overall, positive romantic relationships among adolescents can result in long-term benefits. High-quality romantic relationships are associated with higher commitment in early adulthood and are positively associated with self-esteem, self-confidence, and social competence. For example, an adolescent with positive self-confidence is likely to consider themselves a more successful partner, whereas negative experiences may lead to low confidence as a romantic partner. Adolescents often date within their demographic in regards to race, ethnicity, popularity, and physical attractiveness. However, there are traits in which certain individuals, particularly adolescent girls, seek diversity. While most adolescents date people approximately their own age, boys typically date partners the same age or younger; girls typically date partners the same age or older.

Some researchers are now focusing on learning about how adolescents view their own relationships and sexuality; they want to move away from a research point of view that focuses on the problems associated with adolescent sexuality. College Professor Lucia O'Sullivan and her colleagues found that there were no significant gender differences in the relationship events adolescent boys and girls from grades 7-12 reported. Most teens said they had kissed their partners, held hands with them, thought of themselves as being a couple and told people they were in a relationship. This means that private thoughts about the relationship as well as public recognition of the relationship were both important to the adolescents in the sample. Sexual events (such as sexual touching, sexual intercourse) were less common than romantic events (holding hands) and social events (being with one's partner in a group setting). The researchers state that these results are important because the results focus on the more positive aspects of adolescents and their social and romantic interactions rather than focusing on sexual behavior and its consequences.

Adolescence marks a time of sexual maturation, which manifests in social interactions as well. While adolescents may engage in casual sexual encounters (often referred to as hookups), most sexual experience during this period of development takes place within romantic relationships. Adolescents can use technologies and social media to seek out romantic relationships as they feel it is a safe place to try out dating and identity exploration. From these social media encounters, a further relationship may begin. Kissing, hand holding, and hugging signify satisfaction and commitment. Among young adolescents, "heavy" sexual activity, marked by genital stimulation, is often associated with violence, depression, and poor relationship quality. This effect does not hold true for sexual activity in late adolescence that takes place within a romantic relationship. Some research suggest that there are genetic causes of early sexual activity that are also risk factors for delinquency, suggesting that there is a group who are at risk for both early sexual activity and emotional distress. For older adolescents, though, sexual activity in the context of romantic relationships was actually correlated with lower levels of deviant behavior after controlling for genetic risks, as opposed to sex outside of a relationship (hook-ups)

Dating violence is fairly prevalent within adolescent relationships. When surveyed, 10-45% of adolescents reported having experienced physical violence in the context of a relationship while a quarter to a third of adolescents reported having experiencing psychological aggression. This reported aggression includes hitting, throwing things, or slaps, although most of this physical aggression does not result in a medical visit. Physical aggression in relationships tends to decline from high school through college and young adulthood. In heterosexual couples, there is no significant difference between the rates of male and female aggressors, unlike in adult relationships.

In contemporary society, adolescents also face some risks as their sexuality begins to transform. While some of these, such as emotional distress (fear of abuse or exploitation) and sexually transmitted infections/diseases (STIs/STDs), including HIV/AIDS, are not necessarily inherent to adolescence, others such as teenage pregnancy (through non-use or failure of contraceptives) are seen as social problems in most western societies. One in four sexually active teenagers will contract an STI. Adolescents in the United States often chose "anything but intercourse" for sexual activity because they mistakenly believe it reduces the risk of STIs. Across the country, clinicians report rising diagnoses of herpes and human papillomavirus (HPV), which can cause genital warts, and is now thought to affect 15 percent of the teen population. Girls 15 to 19 have higher rates of gonorrhea than any other age group. One-quarter of all new HIV cases occur in those under the age of 21. Multrine also states in her article that according to a March survey by the Kaiser Family Foundation, eighty-one percent of parents want schools to discuss the use of condoms and contraception with their children. They also believe students should be able to be tested for STIs. Furthermore, teachers want to address such topics with their students. But, although 9 in 10 sex education instructors across the country believe that students should be taught about contraceptives in school, over one quarter report receiving explicit instructions from school boards and administrators not to do so. According to anthropologist Margaret Mead, the turmoil found in adolescence in Western society has a cultural rather than a physical cause; they reported that societies where young women engaged in free sexual activity had no such adolescent turmoil.

Culture

Summary

Japanese gyaru girls in Tokyo

There are certain characteristics of adolescent development that are more rooted in culture than in human biology or cognitive structures. Culture has been defined as the "symbolic and behavioral inheritance received from the past that provides a community framework for what is valued". Culture is learned and socially shared, and it affects all aspects of an individual's life. Social responsibilities, sexual expression, and belief system development, for instance, are all things that are likely to vary by culture. Furthermore, distinguishing characteristics of youth, including dress, music and other uses of media, employment, art, food and beverage choices, recreation, and language, all constitute a youth culture. For these reasons, culture is a prevalent and powerful presence in the lives of adolescents, and therefore we cannot fully understand today's adolescents without studying and understanding their culture. However, "culture" should not be seen as synonymous with nation or ethnicity. Many cultures are present within any given country and racial or socioeconomic group. Furthermore, to avoid ethnocentrism, researchers must be careful not to define the culture's role in adolescence in terms of their own cultural beliefs.

Autonomy

The degree to which adolescents are perceived as autonomous beings varies widely by culture, as do the behaviors that represent this emerging autonomy. Psychologists have identified three main types of autonomy: emotional independence, behavioral autonomy, and cognitive autonomy. Emotional autonomy is defined in terms of an adolescent's relationships with others, and often includes the development of more mature emotional connections with adults and peers. Behavioral autonomy encompasses an adolescent's developing ability to regulate his or her own behavior, to act on personal decisions, and to self-govern. Cultural differences are especially visible in this category because it concerns issues of dating, social time with peers, and time-management decisions. Cognitive autonomy describes the capacity for an adolescent to partake in processes of independent reasoning and decision-making without excessive reliance on social validation. Converging influences from adolescent cognitive development, expanding social relationships, an increasingly adultlike appearance, and the acceptance of more rights and responsibilities enhance feelings of autonomy for adolescents. Proper development of autonomy has been tied to good mental health, high self-esteem, self-motivated tendencies, positive self-concepts, and self-initiating and regulating behaviors. Furthermore, it has been found that adolescents' mental health is best when their feelings about autonomy match closely with those of their parents.

A questionnaire called the teen timetable has been used to measure the age at which individuals believe adolescents should be able to engage in behaviors associated with autonomy. This questionnaire has been used to gauge differences in cultural perceptions of adolescent autonomy, finding, for instance, that White parents and adolescents tend to expect autonomy earlier than those of Asian descent. It is, therefore, clear that cultural differences exist in perceptions of adolescent autonomy, and such differences have implications for the lifestyles and development of adolescents. In sub-Saharan African youth, the notions of individuality and freedom may not be useful in understanding adolescent development. Rather, African notions of childhood and adolescent development are relational and interdependent.

Social roles and responsibilities

Portrait of a noble girl c. 1571

The lifestyle of an adolescent in a given culture is profoundly shaped by the roles and responsibilities he or she is expected to assume. The extent to which an adolescent is expected to share family responsibilities is one large determining factor in normative adolescent behavior. For instance, adolescents in certain cultures are expected to contribute significantly to household chores and responsibilities. Household chores are frequently divided into self-care tasks and family-care tasks. However, specific household responsibilities for adolescents may vary by culture, family type, and adolescent age. Some research has shown that adolescent participation in family work and routines has a positive influence on the development of an adolescent's feelings of self-worth, care, and concern for others.

In addition to the sharing of household chores, certain cultures expect adolescents to share in their family's financial responsibilities. According to family economic and financial education specialists, adolescents develop sound money management skills through the practices of saving and spending money, as well as through planning ahead for future economic goals. Differences between families in the distribution of financial responsibilities or provision of allowance may reflect various social background circumstances and intrafamilial processes, which are further influenced by cultural norms and values, as well as by the business sector and market economy of a given society. For instance, in many developing countries it is common for children to attend fewer years of formal schooling so that, when they reach adolescence, they can begin working.

While adolescence is a time frequently marked by participation in the workforce, the number of adolescents in the workforce is much lower now than in years past as a result of increased accessibility and perceived importance of formal higher education. For example, half of all 16-year-olds in China were employed in 1980, whereas less than one fourth of this same cohort were employed in 1990.

Furthermore, the amount of time adolescents spend on work and leisure activities varies greatly by culture as a result of cultural norms and expectations, as well as various socioeconomic factors. American teenagers spend less time in school or working and more time on leisure activities—which include playing sports, socializing, and caring for their appearance—than do adolescents in many other countries. These differences may be influenced by cultural values of education and the amount of responsibility adolescents are expected to assume in their family or community.

Time management, financial roles, and social responsibilities of adolescents are therefore closely connected with the education sector and processes of career development for adolescents, as well as to cultural norms and social expectations. In many ways, adolescents' experiences with their assumed social roles and responsibilities determine the length and quality of their initial pathway into adult roles.

Belief system development

Adolescence is frequently characterized by a transformation of an adolescent's understanding of the world, the rational direction towards a life course, and the active seeking of new ideas rather than the unquestioning acceptance of adult authority. An adolescent begins to develop a unique belief system through his or her interaction with social, familial, and cultural environments. While organized religion is not necessarily a part of every adolescent's life experience, youth are still held responsible for forming a set of beliefs about themselves, the world around them, and whatever higher powers they may or may not believe in. This process is often accompanied or aided by cultural traditions that intend to provide a meaningful transition to adulthood through a ceremony, ritual, confirmation, or rite of passage.

Sexuality

Many cultures define the transition into adultlike sexuality by specific biological or social milestones in an adolescent's life. For example, menarche (the first menstrual period of a female), or semenarche (the first ejaculation of a male) are frequent sexual defining points for many cultures. In addition to biological factors, an adolescent's sexual socialization is highly dependent upon whether their culture takes a restrictive or permissive attitude toward teen or premarital sexual activity. In the United States, specifically adolescents are said to have "raging hormones" that drive their sexual desires. These sexual desires are then dramatized regarding teen sex and seen as "a site of danger and risk; that such danger and risk is a source of profound worry among adults". There is little to no normalization regarding teenagers having sex in the U.S. which causes conflict in how adolescence are taught about sex education. There is a constant debate about whether abstinence-only sex education or comprehensive sex education should be taught in schools and this stems back to whether or not the country it is being taught in is permissive or restrictive. Restrictive cultures overtly discourage sexual activity in unmarried adolescents or until an adolescent undergoes a formal rite of passage. These cultures may attempt to restrict sexual activity by separating males and females throughout their development, or through public shaming and physical punishment when sexual activity does occur. In less restrictive cultures, there is more tolerance for displays of adolescent sexuality, or of the interaction between males and females in public and private spaces. Less restrictive cultures may tolerate some aspects of adolescent sexuality, while objecting to other aspects. For instance, some cultures find teenage sexual activity acceptable but teenage pregnancy highly undesirable. Other cultures do not object to teenage sexual activity or teenage pregnancy, as long as they occur after marriage. In permissive societies, overt sexual behavior among unmarried teens is perceived as acceptable, and is sometimes even encouraged. Regardless of whether a culture is restrictive or permissive, there are likely to be discrepancies in how females versus males are expected to express their sexuality. Cultures vary in how overt this double standard is—in some it is legally inscribed, while in others it is communicated through social convention. Lesbian, gay, bisexual and transgender youth face much discrimination through bullying from those unlike them and may find telling others that they are gay to be a traumatic experience. The range of sexual attitudes that a culture embraces could thus be seen to affect the beliefs, lifestyles, and societal perceptions of its adolescents.

Legal issues, rights and privileges

General issues

A sign outside a sex shop reads "Must Be 18 To Enter" in Chapel Hill, North Carolina.

Adolescence is a period frequently marked by increased rights and privileges for individuals. While cultural variation exists for legal rights and their corresponding ages, considerable consistency is found across cultures. Furthermore, since the advent of the Convention on the Rights of the Child in 1989 (children here defined as under 18), almost every country in the world (except the U.S. and South Sudan) has legally committed to advancing an anti-discriminatory stance towards young people of all ages. This includes protecting children against unchecked child labor, enrollment in the military, prostitution, and pornography. In many societies, those who reach a certain age (often 18, though this varies) are considered to have reached the age of majority and are legally regarded as adults who are responsible for their actions. People below this age are considered minors or children. A person below the age of majority may gain adult rights through legal emancipation.

The legal working age in Western countries is usually 14 to 16, depending on the number of hours and type of employment under consideration. Many countries also specify a minimum school leaving age, at which a person is legally allowed to leave compulsory education. This age varies greatly cross-culturally, spanning from 10 to 18, which further reflects the diverse ways formal education is viewed in cultures around the world.

In most democratic countries, a citizen is eligible to vote at age 18. In a minority of countries, the voting age is as low as 16 (for example, Brazil), and at one time was as high as 25 in Uzbekistan.

The age of consent to sexual activity varies widely between jurisdictions, ranging from 12 to 20 years, as does the age at which people are allowed to marry. Specific legal ages for adolescents that also vary by culture are enlisting in the military, gambling, and the purchase of alcohol, cigarettes or items with parental advisory labels. It should be noted that the legal coming of age often does not correspond with the sudden realization of autonomy; many adolescents who have legally reached adult age are still dependent on their guardians or peers for emotional and financial support. Nonetheless, new legal privileges converge with shifting social expectations to usher in a phase of heightened independence or social responsibility for most legal adolescents.

Alcohol and illicit drug use

Prevalence

Following a steady decline, beginning in the late 1990s up through the mid-2000s, illicit drug use among adolescents has been on the rise in the U.S. Aside from alcohol, marijuana is the most commonly indulged drug habit during adolescent years. Data collected by the National Institute on Drug Abuse shows that between the years of 2007 and 2011, marijuana use grew from 5.7% to 7.2% among 8th grade students; among 10th grade students, from 14.2% to 17.6%; and among 12th graders, from 18.8% to 22.6%. Additional, recent years have seen a surge in popularity of MDMA; between 2010 and 2011, the use of MDMA increased from 1.4% to 2.3% among high school seniors. The heightened usage of ecstasy most likely ties in at least to some degree with the rising popularity of rave culture.

One significant contribution to the increase in teenage substance abuse is an increase in the availability of prescription medication. With an increase in the diagnosis of behavioral and attentional disorders for students, taking pharmaceutical drugs such as Vicodin and Adderall for pleasure has become a prevalent activity among adolescents: 15.2% of high school seniors report having abused prescription drugs within the past year.

Teenage alcohol drug use is currently at an all-time low. Out of a polled body of students, 4.4% of 8th graders reported having been on at least one occasion been drunk within the previous month; for 10th graders, the number was 13.7%, and for 12th graders, 25%. More drastically, cigarette smoking has become a far less prevalent activity among American middle- and high-school students; in fact, a greater number of teens now smoke marijuana than smoke cigarettes, with one recent study showing a respective 15.2% versus 11.7% of surveyed students. Recent studies have shown that male late adolescents are far more likely to smoke cigarettes rather than females. The study indicated that there was a discernible gender difference in the prevalence of smoking among the students. The finding of the study show that more males than females began smoking when they were in primary and high schools whereas most females started smoking after high school. This may be attributed to recent changing social and political views towards marijuana; issues such as medicinal use and legalization have tended towards painting the drug in a more positive light than historically, while cigarettes continue to be vilified due to associated health risks.

Different drug habits often relate to one another in a highly significant manner. It has been demonstrated that adolescents who drink at least to some degree may be as much as sixteen times more likely than non-drinkers to experiment with illicit drugs.

Social influence

Irish teenagers over 18 hanging around outside a bar. People under 18 are not allowed to drink outside the home; this is not strictly enforced in Ireland.

Peer acceptance and social norms gain a significantly greater hand in directing behavior at the onset of adolescence; as such, the alcohol and illegal drug habits of teens tend to be shaped largely by the substance use of friends and other classmates. In fact, studies suggest that more significantly than actual drug norms, an individual's perception of the illicit drug use by friends and peers is highly associated with his or her own habits in substance use during both middle and high school, a relationship that increases in strength over time. Whereas social influences on alcohol use and marijuana use tend to work directly in the short term, peer and friend norms on smoking cigarettes in middle school have a profound effect on one's own likelihood to smoke cigarettes well into high school. Perhaps the strong correlation between peer influence in middle school and cigarette smoking in high school may be explained by the addictive nature of cigarettes, which could lead many students to continue their smoking habits from middle school into late adolescence.

Demographic factors

Until mid-to-late adolescence, boys and girls show relatively little difference in drinking motives. Distinctions between the reasons for alcohol consumption of males and females begin to emerge around ages 14–15; overall, boys tend to view drinking in a more social light than girls, who report on average a more frequent use of alcohol as a coping mechanism. The latter effect appears to shift in late adolescence and onset of early adulthood (18–19 years of age); however, despite this trend, age tends to bring a greater desire to drink for pleasure rather than coping in both boys and girls.

Drinking habits and the motives behind them often reflect certain aspects of an individual's personality; in fact, four dimensions of the Five-Factor Model of personality demonstrate associations with drinking motives (all but 'Openness'). Greater enhancement motives for alcohol consumption tend to reflect high levels of extraversion and sensation-seeking in individuals; such enjoyment motivation often also indicates low conscientiousness, manifesting in lowered inhibition and a greater tendency towards aggression. On the other hand, drinking to cope with negative emotional states correlates strongly with high neuroticism and low agreeableness. Alcohol use as a negative emotion control mechanism often links with many other behavioral and emotional impairments, such as anxiety, depression, and low self-esteem.

Research has generally shown striking uniformity across different cultures in the motives behind teen alcohol use. Social engagement and personal enjoyment appear to play a fairly universal role in adolescents' decision to drink throughout separate cultural contexts. Surveys conducted in Argentina, Hong Kong, and Canada have each indicated the most common reason for drinking among adolescents to relate to pleasure and recreation; 80% of Argentinian teens reported drinking for enjoyment, while only 7% drank to improve a bad mood. The most prevalent answers among Canadian adolescents were to "get in a party mood," 18%; "because I enjoy it," 16%; and "to get drunk," 10%. In Hong Kong, female participants most frequently reported drinking for social enjoyment, while males most frequently reported drinking to feel the effects of alcohol.

Media

Body image

Teenage girl texting

Much research has been conducted on the psychological ramifications of body image on adolescents. Modern day teenagers are exposed to more media on a daily basis than any generation before them. Recent studies have indicated that the average teenager watches roughly 1500 hours of television per year. As such, modern day adolescents are exposed to many representations of ideal, societal beauty. The concept of a person being unhappy with their own image or appearance has been defined as "body dissatisfaction". In teenagers, body dissatisfaction is often associated with body mass, low self-esteem, and atypical eating patterns. Scholars continue to debate the effects of media on body dissatisfaction in teens.

Media profusion

Because exposure to media has increased over the past decade, adolescents' utilization of computers, cell phones, stereos and televisions to gain access to various mediums of popular culture has also increased. Almost all American households have at least one television, more than three-quarters of all adolescents' homes have access to the Internet, and more than 90% of American adolescents use the Internet at least occasionally. As a result of the amount of time adolescents spend using these devices, their total media exposure is high. In the last decade, the amount of time that adolescents spend on the computer has greatly increased. Online activities with the highest rates of use among adolescents are video games (78% of adolescents), email (73%), instant messaging (68%), social networking sites (65%), news sources (63%), music (59%), and videos (57%).

Social networking

Within the past ten years, the amount of social networking sites available to the public has greatly increased as well as the number of adolescents using them. Several sources report a high proportion of adolescents who use social media: 73% of 12–17 year olds reported having at least one social networking profile; two-thirds (68%) of teens text every day, half (51%) visit social networking sites daily, and 11% send or receive tweets at least once every day. In fact, more than a third (34%) of teens visit their main social networking site several times a day. One in four (23%) teens are "heavy" social media users, meaning they use at least two different types of social media each and every day.

Although research has been inconclusive, some findings have indicated that electronic communication negatively affects adolescents' social development, replaces face-to-face communication, impairs their social skills, and can sometimes lead to unsafe interaction with strangers. A 2015 review reported that "adolescents lack awareness of strategies to cope with cyberbullying, which has been consistently associated with an increased likelihood of depression." Studies have shown differences in the ways the internet negatively impacts the adolescents' social functioning. Online socializing tends to make girls particularly vulnerable, while socializing in Internet cafés seems only to affect boys academic achievement. However, other research suggests that Internet communication brings friends closer and is beneficial for socially anxious teens, who find it easier to interact socially online. The more conclusive finding has been that Internet use has a negative effect on the physical health of adolescents, as time spent using the Internet replaces time doing physical activities. However, the Internet can be significantly useful in educating teens because of the access they have to information on many various topics.

Transitions into adulthood

A young U.S. Marine in the Vietnam War, 1965

A broad way of defining adolescence is the transition from child-to-adulthood. According to Hogan & Astone (1986), this transition can include markers such as leaving school, starting a full-time job, leaving the home of origin, getting married, and becoming a parent for the first time. However, the time frame of this transition varies drastically by culture. In some countries, such as the United States, adolescence can last nearly a decade, but in others, the transition—often in the form of a ceremony—can last for only a few days.

Some examples of social and religious transition ceremonies that can be found in the U.S., as well as in other cultures around the world, are Confirmation, Bar and Bat Mitzvahs, Quinceañeras, sweet sixteens, cotillions, and débutante balls. In other countries, initiation ceremonies play an important role, marking the transition into adulthood or the entrance into adolescence. This transition may be accompanied by obvious physical changes, which can vary from a change in clothing to tattoos and scarification. Furthermore, transitions into adulthood may also vary by gender, and specific rituals may be more common for males or for females. This illuminates the extent to which adolescence is, at least in part, a social construction; it takes shape differently depending on the cultural context, and may be enforced more by cultural practices or transitions than by universal chemical or biological physical changes.

Promoting positive changes in adolescents

At the decision-making point of their lives, youth is susceptible to drug addiction, sexual abuse, peer pressure, violent crimes and other illegal activities. Developmental Intervention Science (DIS) is a fusion of the literature of both developmental and intervention sciences. This association conducts youth interventions that mutually assist both the needs of the community as well as psychologically stranded youth by focusing on risky and inappropriate behaviors while promoting positive self-development along with self-esteem among adolescents.

Criticism

The concept of adolescence is criticized by some experts such as Robert Epstein, stating that an undeveloped brain is not the main cause of teenagers' turmoils. Some argue that adolescence is a modern recent invention by society and that forcing young people to stay immature for extended periods of time is detrimental.

Other critics of the concept of adolescence do point at individual differences in brain growth rate, citing that some (though not all) early teens still have infantile undeveloped corpus callosums, concluding that "the adult in *every* adolescent" is too generalizing. These people tend to support the notion that a more interconnected brain makes more precise distinctions (citing Pavlov's comparisons of conditioned reflexes in different species)and that there is a non-arbitrary threshold at which distinctions become sufficiently precise to correct assumptions afterward as opposed to being ultimately dependent on exterior assumptions for communication. These people argue that this threshold is the one at which an individual is objectively capable of speaking for himself or herself, as opposed to culturally arbitrary measures of "maturity" which often treat this ability as a sign of "immaturity" merely because it leads to questioning of authorities. These people also stress the low probability of the threshold being reached at a birthday, and instead advocate non-chronological emancipation at the threshold of afterward correction of assumptions. They sometimes cite similarities between "adolescent" behavior and inmate behavior in adults in prison camps such as aggression being explainable by oppression and "immature" financial or other risk behavior being explainable by a way out of captivity being more worth to captive people than any incremental improvement in captivity, and argue that this theory successfully predicted remaining "immature" behavior after reaching the age of majority by means of longer-term traumatization. In this context, they refer to the fallibility of official assumptions about what is good or bad for an individual, concluding that paternalistic "rights" may harm the individual. They also argue that since it never took many years to move from one group to another to avoid inbreeding in the paleolithic, evolutionary psychology is unable to account for a long period of "immature" risk behavior.

See also

• Adolescent medicine
• Children and adolescents in the United States
• Clique
• Emerging adulthood and early adulthood
• Ephebophilia – a sexual preference in which an adult is primarily or exclusively sexually attracted to mid to late adolescents
• Fear of youth
• Relational aggression
• Shōnen
• Student voice
• Suitable age and discretion
• Timeline of young people's rights in the United Kingdom
• Timeline of young people's rights in the United States
• Young adult (psychology)
• Youth culture
• Young worker safety and health