Time perception

Time flies when you’re having fun, the saying goes; now there’s scientific evidence to back that up.

Dr. Anthony Chaston and Dr. Alan Kingstone of the University of Alberta’s Department of Psychology gave subjects tests that required them to find specific items in various images. Before they began, they were told that once the test was over, they would be asked to estimate how long it took.

In the simplest of the seven different levels of test, the items sought were a different colour than everything else, or hardly hidden at all. In the more difficult levels, the items were placed among many similar-looking items–or weren’t even presentl.

The results: the harder the search task, the smaller the estimate of how long the test had taken. In other words, the more engaged the mind on a task, the faster time seems to go by.

The subjects were told ahead of time that they would be asked to estimate the test’s length because people are generally better at predicting how long a task will take than estimating how long it took.

How we perceive time is a big question, and one that received a thorough philosophical workout, going back to at least St. Augustine, even before scientists started struggling with it. The fundamental scientific question has boiled down to, “Is there a clock mechanism in our brains that tracks the passage of time, or is our perception that time is passing just a by-product of memory and our senses?”

There are probably different mechanisms at work for different lengths of time. For instance, we’re very good at judging the relative lengths of very short flashes of light or bursts of sound. John Wearden, a psychologist at the University of Manchester in the U.K. who specializes in time perception studies, thinks in that case the brain is really reacting to differences in the energy of the stimulus, rather than the duration.

Then there’s our perception of much longer intervals. Even at my tender age I’ve noted that the years seem to fly by faster than they used to. Wearden doesn’t think this perception is related to the brain’s built-in clock, either; he suggests it’s a function of our brain’s tendency to, in memory, diminish the importance of hours spent on boring, routine tasks, and highlight the importance of hours spent on challenging tasks. Since, as we get older, more of what we do year to year tends to fall into set patterns, we commit fewer details to memory and thus, in retrospect, it seems that the year went by with little happening.

Over intermediate timeframes, however–from about a tenth of a second up to a few minutes–the brain seems to be able to measure time directly. When test subjects are asked to press a key after a short interval, which may vary from half a second to several seconds, after a little training they’re usual accurate to within a few percent.

Researchers at the Medical College of Wisconsin in Milwaukee and Veterans Affairs Medical Center in Albuquerque may have recently pinpointed the location of the brain mechanism that makes this possible. Using functional magnetic resonance imaging, they scanned the brains of 17 young men and women while they listened to two sets of two consecutive tones each, and were asked to judge whether the silence between the second pair of tones was longer or shorter than the silence between the first pair of tones. The brain scan indicated that the timekeeping functions in the brain are governed by the basal ganglia and the right parietal cortex.

This makes sense, because the basal ganglia’s cells primarily contain the neurotransmitter dopamine, and dopamine levels have long been linked to time perception. For instance, Parkinson’s disease patients, who have an abnormal reduction in dopamine within the basal ganglia, commonly experience problems with time perception–and those problems partially improve when dopamine levels are increased.

There are many other examples. Drugs that increase the amount of dopamine, such as cocaine and methamphetamine, seem to speed up the internal clock; so do moments of high stress, when dopamine and other neurotransmitters flood the brain. As a result, time seems to stand still or move incredibly slowly.

Marijuana and some other substances, on the other hand, decrease dopamine levels, making time seem to pass faster. Dopamine levels also fall with age, beginning in the 20s and continuing thereafter. That may also contribute to the feeling older people have that time is passing more quickly.

Gee. Wasn’t it just yesterday I was writing last week’s column?

Permanent link to this article: https://edwardwillett.com/2004/08/time-perception/


    • Greg on May 29, 2011 at 5:37 am
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