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Effects of Drugs on Time Perception

Stimulants such as thyroxine, caffeine, and amphetamines lead to overestimation of time intervals by both humans and rats, while depressants and anesthetics such as barbiturates, nitrous oxide can have the opposite effect and lead to underestimation of time intervals. The level of activity in the brain of neurotransmitters such as dopamine and norepinephrine may be the reason for this. A research on stimulant-dependent individuals (SDI) showed several abnormal time processing characteristics including larger time differences for effective duration discrimination, and overestimating the duration of a relatively long time interval. Altered time processing and perception in SDI could explain the difficulty SDI have with delaying gratification. Another research studied the dose-dependent effect in methamphetamine dependents with short term abstinence and its effects on time perception. Results shows that motor timing but not perceptual timing, was altered in meth dependents, which persisted for at least 3 months of abstinence. Dose-dependent effects on time perception were only observed when short-term abstinent meth abusers processed long time intervals. The study concluded that time perception alteration in meth dependents is task specific and dose dependent.

Hallucinogens such as psilocybin, marijuana, mescaline, LSD, makes subjects’ estimate of absolute duration, very long. The effect of cannabis on time perception has been studied with inconclusive results mainly due to methodological variations and the paucity of research. Even though 70% of time estimation studies report over-estimation, the findings of time production and time reproduction studies remain inconclusive.. Studies show consistently throughout the literature that most cannabis users self-report the experience of a slowed perception of time. In the laboratory, researchers have confirmed the effect of cannabis on the perception of time in both humans and animals. Using PET Scans it was observed that participants who showed a decrease in cerebellar CBF also had a significant alteration in time sense. The relationship between decreased cerebellar flow and impaired time sense is of interest as the cerebellum is linked to an internal timing system. In addition, a marijuana user may underestimate the speed of a motor vehicle, increasing the chances of accident.

Effects of Body Temperature on Time Perception

The chemical clock hypothesis implies a causal link between body temperature and the perception of time.

Past work show that increasing body temperature tends to make individuals experience a dilated perception of time and they perceive durations longer than they actually did, ultimately leading them to under-estimate time durations. While decreasing body temperature has the opposite effect - causing participants to experience a condensed perception of time leading them to over-estimate time duration - the observations of the latter type were rare. Research establishes a parametric effect of body temperature on time perception with higher temperatures generally producing faster subjective time and vice versa. This is especially seen to be true under changes in arousal levels and stressful events.

Effects of clinical disorders

Effect of Attention Deficit Hyperactivity Disorder(ADHD) on Time Perception

Positive, negative, neutral words associated with an individual who diagnosed with ADHD.

Attention deficit hyperactivity disorder (ADHD) is a behavioral disorder often marked by either inattention and hyperactivity or impulsivity that leads to impairment in social, academic or occupational activities. Some people can also show symptoms belonging to both subtypes.

ADHD is linked to abnormalities in dopamine levels in the brain as well as to noticeable impairments in time perception. Numerous imaging studies have demonstrated that the caudate nucleus and globus pallidus (striatum) which contain a high density of DA receptors are smaller in ADHD than in control groups, ADHD groups have smaller posterior brain regions (e.g.,occipital lobes) and areas involved in coordinating activities of multiple brain regions (e.g., rostrum and splenium of corpus collosum and cerebellar vermis). These volumetric differences between the two groups correlate with severity of ADHD and its symptoms. It appears that the abnormal fronto-parietal and fronto-striato- cerebellar networks in ADHD individuals seem to mediate the found defects in a broad range of timing tasks; indicating that ADHD can at least partly, be seen as a disorder of an abnormal temporal processing (Noreika et al., 2013).

Individuals with ADHD have difficulties in discrimination activities and time estimation. It seems to them that time is passing by without them being able to complete tasks accurately. A study by Noreika et al.(2013, p.260) found that the most consistent deficits in ADHD seemed to affect sensorimotor synchronization, duration discrimination, duration reproduction and delay discounting tasks. Another study by Barkley (1997) found that problems with the working memory can affect the development of a sense of time in children with ADHD.

Studies conducted in 1997 tested the relationship between ADHD and deficiency in sense of time perception; predicting and evaluating the effects of interval duration, distraction, and stimulant medication (methylphenidate (MPH) on the reproductions of temporal durations in children with ADHD. Results showed that time perception is impaired in children with ADHD and the capacity to accurately reproduce time intervals in ADHD children does not seem to improve with administration of stimulant medication.

Work from 2003 used time reproduction tasks to compare time perception in children with and without ADHD. The results indicate that there was a great discrepancy in the scores between the two groups and indicated that children with ADHD have impaired time perception compared to the children without ADHD. Poor time perception affects the performance of social skills and other adaptive behaviors such as health consciousness and concerns for safety.

Although ADHD has been associated with neurologic abnormalities in the mesolimbic and dopaminergic systems, contrary to the 1997 study talked above, recent studies have found that when individuals with ADHD are treated medically, their perception of time tends to normalize. Ptacek et al. (2019) suggests that the existing evidence of altered time perception could be used to improve the diagnostic criteria of ADHD as well as help to improve the recognition of the symptoms in clinical settings.

Effect of Autism Spectrum Disorder(ASD) on Time Perception

Autism Spectrum Disorder (ASD), is a behavioral disorder characterized by severe and pervasive impairment in several areas of development including but not limited to reciprocal skills, social interaction skills, communication & language skills. Apart from these struggles self-reports and reports from people (parents, teachers, and clinicians) having regular contact with people with ASD indicate that they often see them struggle with time perception and sense of time. Individuals with autism seem to have a basic inability to make sense of past and present experiences, which has to do with comprehending the passage of time and linking it with current ongoing activities.

Allman and Falter (2015) present three general trends in the research on abnormal timing and time perception in ASD. Firstly, studies concentrating on the sub-second range have tended to find superior temporal discrimination differences in people with ASD. Secondly, studies in the supra-second range have tended to find impairments in longer durations beyond the limits of the ‘psychological present’ of about 3 seconds as described by William James (1890) and connected with increased variability. Thirdly, there is initial evidence indicating problems with conceptual notions of time in ASD (Allman & Falter, 2015).

Effect of Schizophrenia on Time Perception

Schizophrenia is a mental disorder characterized by delusions, hallucinations, disorganized speech and behavior. Individuals suffering from schizophrenia have a varied perception of time compared to neurotypicals; also are less precise in judging the temporal order of events. Time perception impairment in schizophrenia was originally described by clinicians and later addressed in laboratory. Past work on schizophrenics indicated a great impairment in time sensitivity and perception leading to overestimation of time intervals. Due to the cognitive impairments that the disorder poses, there have not been any definitive conclusions about the nature of time perception irregularities. A recent study aimed to isolate a genuine time perception disorder (functioning of the internal clock) in schizophrenia by testing id the patients' internal clock runs faster compared to healthy controls. Results indicated significant correlations between Time perception tasks and memory outcomes suggesting such impairments are directly related to memory impairment in schizophrenia. Schizophrenia has been associated with abnormalities in dopamine (DA) transmissions (Seeman et al., 2006), which in turn, have been linked to the speed of the internal clock (Cheng et al., 2007). The time overestimation has been suggested to be caused by accelerated time processing and may be associated with psychosis (Droit-Volet and Meck, 2007)

Effect of Depression on Time Perception

Depression is a mood disorder that is characterized by persistent feeling of sadness and loss of interest. Affective and cognitive disturbances are significant features in depression. These disturbances manifest as dysfunctional psychological tendencies affecting motivational behavior in performing tasks and also invoke disturbances related to time. Clinical evidences suggest that time perception during depressive episodes tend to be underestimated. However, there are also evidences to the contrary. A recent study focused to test if affective and cognitive disturbances in depression are synonymous with the subjective inability to accurately perceive time. The results indicated that temporal estimations of time are significantly affected by the cognitive and affective load in depressed participants.

Psychologists at Johannes Gutenberg University Mainz (JGU) discovered that although depressed individuals perceive slow time passage, their estimates are just as accurate as normal individuals when asked to judge the duration of a specific time interval, such as two seconds or two minutes. People with depression often tend to experience the world differently from others, report changes in appetite, and sometimes feel that time drags on. In a study, mathematical psychologist Diana Kornbrot of the University of Hertfordshire and her colleagues applied the Beck Depression Inventory (BDI) to gauge the mood of 46 participants. They found a correlation between participants’ BDI scores and the accuracy with which they could estimate the length of the sounds they heard and produced: Those with higher scores made more accurate estimates than those with lower scores. Another study examined changes in time perception as a function of depressive symptoms, with the Beck Depression Inventory (BDI). The results of this study indicated that the probe durations were underestimated by the depressive participants. The study also assessed the sadness scores by the Brief Mood Inventory Scale (BMIS) and suggested that the emotional state of sadness in the depressive participants goes some way to explaining their temporal performance. These results may be explained by a slowing down of the internal clock in the depressive participants.

It appears that those with mild depression seem to be better at paying attention to short periods of time, says psychologist Rachel Msetfi of the University of Limerick, a co-author of the study. These findings also suggest that people with depression experience a time dilation effect, and in effect support the notion of depressive realism, which suggests that people who are depressed have a more accurate perception of reality than others. Msetfi believes that this time dilation might be related to one of the symptoms of severe depression - helplessness, or the feeling that they are not in control of their lives, and this is usually accompanied by a feeling of guilt. Time perception is crucial for agency, the sense that we are in control of our actions. Normally, our actions are followed very closely in time by their consequences; this can give us the sense that the two are causally related, and that we are responsible for the consequences of our actions.