Talk:Phi phenomenon

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Isn't this the basis of tv? a bunch of images being flashed on screen, each one slightly different then the last? there is no real motion non tv either, just us perceiving motion from rapid succession of still shots.

You're talking about the gif, I take it...Yeah, it is, as far as I can see. This is beta!
It's not exactly my area of specialization, but it seems pretty damn clear to me that it's not phi. The only "motion" I see is the brightened yellow disk moving around all over the place, so if this is a phi gif I need to contact my shrink and tell her I'm the only human being ever to see shapes in my phi. Really an article whose gist, and rightly so, is how easily phi is confused with beta, wikipedia's illustration of what phi really is, is in fact a perfect illustration of beta? I'm deleting this B.S. before any more of America's famously vision-theory-obsessed teenagers get led astray by it, and we start losing out to the Communist kids who are getting their phi information from people who know what they're talking about. 09:27, 31 May 2007 (UTC)

Please note that the illustration of phi phenomenon 'the lilac chaser' included in this article is actually showing borderline beta movement. The apparent movement called phi phenomenon and beta movement are defined in terms of the time span between appearance of one dot and the next. If the time span between the first dot and the second is approximately 60 milliseconds, this will result in a perception of continuous movement between the two stimuli. At approximately 200 milliseconds, the resulting perception will be of one stimulus followed by the next, without any movement between them. Therefore Phi phenomenon occurs around the 60 millisecond mark whereas Beta movement occurs around 200 milliseconds. ref "Phi Phenomenon." Encyclopedia of Time: Science, Philosophy, Theology, & Culture. 2009. SAGE Publications. 29 Sep. 2009. <>.--Rodmunday (talk) 16:57, 2 July 2010 (UTC)

A visual example of the phi phenomenon would be helpful. The phi phenomenon doesn't actually refer to perceived movement of objects, but a perceived motion of the space between the objects. What you would see is the background between the objects moving kind of like a flapping flag. (Steinman et al., 2000. "Phi is not beta, and why Wertheimer's discovery launched the Gestalt revolution") —Preceding unsigned comment added by (talk) 03:44, 29 November 2010 (UTC)

Oh! I had to read this discussion before I understood, so I think the gif for phi movement should be sped up. — Preceding unsigned comment added by (talk) 10:38, 19 August 2011 (UTC)

The section "persistence of vision" is very badly written. I can't edit it, because I literally cannot tell what it is the writer was trying to convey. Could somebody who understands the phenomenon please rewrite, making it intelligible to non-scientists? Theonemacduff (talk) 18:31, 22 March 2011 (UTC)

Poorly written with bad references[edit]

I don't want to make any changes, as I'm not too familiar with Wikipedia policy. One issue that stands out, however, is that there isn't a clear distinction between the phi phenomenon and beta movement. This is an issue as "beta movement" doesn't have it's own page, but rather redirects to this.

The section titled "The phi phenomenon is not beta movement" does a very poor job at distinguishing the two, and then references a source which doesn't seem to have any information on the subject. Again, I don't want to change it because it may be an issue with the page loading for me, but the external link seems very outdated and it appears that the content has been changed, and no longer contains relevant information (the demos that are supposed to show the effect don't load/aren't there). Pena47 (talk) 09:34, 10 July 2011 (UTC)

I totally agree with this, both articles (Beta movement) do a very poor job at distinguishing the two. I am unfortunately very unable to correct the article due to the nature of the problem itself. -- (talk) 21:34, 7 November 2012 (UTC)
This article is indeed so poor that it can't make itself properly clear. The article persistence of vision states that it was demonstrated in 1912 that it's not said persistence that makes movie films possible but this obscure "phi phenomenon" here. Once the viewer gets here, they are initially presented with the same claim, and then a purely phenomenological definition of "the phi phenomenon is that humans perceive still images as motion", and that is all. How awesome! I woulda never suspected!
So far, this article reads like some occult para-psychic new age bullshit trying to explain gravity by some magic elves inside the ground, or Scientology telling people they can warp matter by means of pure thought rays. It certainly is about as inept in making itself clear as certain new age gurus. -- (talk) 08:00, 21 May 2013 (UTC)

Unclear difference between Phi phenomenon and Beta movement[edit]

The article currently states: "The phi phenomenon is similar to beta movement in that both cause sensation of movement; however, the phi phenomenon is an apparent movement caused by luminous impulses in sequence, whereas beta movement is an apparent movement caused by luminous stationary impulses"

This doesn't explain the difference AT ALL. To me, both sentences seem to be saying the same with slightly different words. What's the difference between "luminous impulses in sequence" and "luminous stationary impulses"? It doesn't help that in both cases the impulses are "stationary"; there is no actual movement.

Please, can someone who understands this explain the difference in clear terms? (talk) 12:01, 2 October 2013 (UTC)

This article is indeed a bit unclear and the illustrations are accurate but they don't make the best distinction between the phenomena. Here is the important difference: notice that in the phi phenomenon, all of the points of movement are present, and one is getting "covered up" in each new frame. That creates the sequence. In beta movement, a single new dot is present each position, and it is the continual refreshing of the dot that creates the illusion of sequence. I think that's the main distinction between the two, though I could be off. Here is a different sample of beta movement. The difference is a little hard to verbalize, but I hope this helps a little. The page is definitely far too ambiguous. ~ Boomur [] 22:07, 3 October 2013 (UTC)
I think the two related articles here are seriously confusing. Based on the "Experimental demonstration" section, [1], [2], and the Motion perception article section on first-order perception, maybe a clearer explanation is possible. From the article: "The classic phi phenomenon experiment involves a viewer or audience watching a screen, upon which the experimenter projects two images in succession. The first image depicts a line on the left side of the frame. The second image depicts a line on the right side of the frame. The time/lag (the inter-stimulus interval, ISI) between offset of the first and onset of the second line is varied." With a very low lag between the image flashes, you get the phi phenomenon where there's apparent motion of an occluding "object" (the same color as the background) passing over the lines. With more lag between the flashes, you get beta movement where the object itself appears to move. In beta movement, the object shown in each frame appears to move, whereas in the phi phenomenon there are two objects and something appears to be moving between and over them. 2601:196:4700:30AF:1909:F3FE:2E74:E777 (talk) 01:27, 23 January 2017 (UTC)

Introducing some new references[edit]

I think this article would benefit from injecting some references from the literature, which contradict much of the information on this page. In this article from Vision Science, published in 2000, Robert Steinman, Zyg Pizlo, and Filip Pizlo review Wertheimer's original article, plus some early follow-ups, and carry out controlled replications of the phenomenon in an attempt to set the record straight on the difference between phi and beta.

For one, Wertheimer produced both phi and beta movement with the same pair of slits, contradicting the assertion that 'beta movement is between different points in space, whereas phi is between different images at the same point.' In fact, beta motion (also known as "optimal motion") occurs when the lights are switching about every 60ms. Beta is the phenomenon where it looks like the light is moving continuously from one to another (the kind found in cinema).

If you make it slightly faster, somewhere in the region between beta motion and simultaneity, people see an ambiguously shaped dark region flickering or shifting in the middle of the two different points. 'Disembodied movement.' This is phi. It's significant because your visual system is actually forming a qualitatively new, primitive object from the sources, not just smooth continuous movement of existing sources. There's a visual demonstration by the authors here.

This account is backed up independently by Stephen Palmer's excellent textbook Vision Science (see p. 472 and Fig. 10.1.6) and, of course, Wertheimer's original 1912 paper, available since 2012 in English translation through MIT Press. I'm new to editing articles, but if everyone can agree on these sources, I'd be happy to make the changes to the page. (talk) 06:04, 4 April 2014 (UTC)