Post by Lani Cupo
The adage “time flies when you’re having fun” may be a cliché, but most people would agree that their favorite activities seem to fly by, while events they dread seem to pass by slowly. Holding a plank, for example, for 90 seconds may feel like forever while browsing social media for ten minutes can pass in the blink of an eye. How does our time perception develop and how accurate are we in perceiving time?
How does the perception of time develop?
Time perception is an essential part of human life and survival and infants begin learning about time from birth. Psychological studies demonstrate that infants can detect changes in repetitive sequences of stimuli at predictable intervals. For example, in a study from the 1970s, infants placed in a dark room were exposed to light every 20 seconds for 4 seconds, triggering a constriction in their pupils. After a learning phase, their pupils continued to constrict after 20 seconds, even when the light did not change, suggesting the infants already have an internal mechanism for keeping track of time. The emotion of surprise can be measured in infants by assessing their gaze because they will spend more time looking at surprising events. Using this approach, researchers found longer gaze time when event duration changed (such as the puppet opening its mouth for 4 seconds instead of 2), further suggesting that infants keep track of the passage of time and recognize when the duration of a rhythmic event changes.
An infant’s sense of time develops over childhood. Children and adults are able to successfully judge when a second stimulus matches the duration of the first, and accuracy at this task improves between the ages of 3 and 10. A “time bisection” has been used to measure time perception. In this task, participants learn two “anchor” stimuli, one short and one long, and are then exposed to new stimuli of various lengths. Participants must decide which “anchor” stimuli match the novel stimuli most. This allows researchers to study participants’ sense of time. Newborns can differentiate between stimuli with ratios of 1:2 (such as 5 seconds and 10 seconds), but older infants (10 months) can distinguish between more difficult ratios of 2:3 (such as 6 seconds and 9 seconds). While some adults can distinguish closer ratios, there is considerable inter-subject variability. These findings suggest that our time perception abilities improve throughout the first decade of life.
As children get older, they develop explicit knowledge of the concept of time. Time distortions, like perceiving the passage of time as slower or faster than in reality, are more common among young children. One potential explanation is that an explicit understanding of time is linked to several other psychological processes which are still being developed in children. For example, working memory capacity increases between childhood and adulthood, which may contribute to decreased time distortions. In fact, a recent study associated both working memory capacity and concentration capacity with improved performance on a time bisection task across ages. This suggests as the capacity for working memory develops, so does the precision of time perception. As children develop cognitive capabilities, they become less susceptible to time distortions. Some experiments suggest the accuracy of time perception peaks in adolescence when compared to children and adults.
How accurate is our time perception?
Recent research suggests that healthy adults may perceive time as passing slower than it actually does, which may not be a bad thing. Compared to patients with orbitofrontal cortex lesions and borderline personality disorder, healthy participants in one study overestimated the duration of 60 and 90-second time intervals, whereas the patient groups were much more accurate. Results of this study suggest individuals with greater impulsivity or frustration perceive time as moving more quickly than neurotypical individuals.
There is some evidence to suggest that time perception is subject to Weber’s Law, which states that the noticeable change in a stimulus is a constant related to the original value of the stimulus. For example, if you start with a one-pound weight and add another one-pound weight, the difference between the weights will be drastic. However, if you start with a fifty-pound weight, adding another pound will be much less noticeable. In the same way, adding two seconds to a duration of ten seconds is noticeable, however adding two seconds to a duration of 90 seconds may not be.
But, if healthy adults perceive time as passing more slowly than it really does, what is the explanation for “time flying by”? Emotions and time are also intricately connected. For example, research shows that emotional events that sustain our attention speed up time, while more neutral events that are emotionally distracting can slow down our perception of time. Research has also shown that while shorter time increments, such as hours, days, or weeks were perceived similarly across ages, decades were seen as passing more quickly with age. One explanation could be that pressures and responsibilities increase with age, such as professional activities and family duties. Further, time often seems to pass more slowly during periods of learning, which are often concentrated before the mid-20s. However, there are certain limitations to using interviews to understand the perception of time, such as the limited experience younger participants have with “past decades.”
Additionally, approach vs. withdrawal motivation has been implicated in altering the perception of time. One study examined the impact of movie viewing on time perception, finding scary movies slowed down time perception, but sad movies did not. This suggests that some emotions like fear, eliciting motivation to withdraw, could serve as an evolutionary advantage in slowing down time perception, giving people more time to react to dangerous situations.
Experimental stimuli in research have been shown to impact time perception. In the laboratory, the modality of a presented stimulus impacts the assessment of duration. For example, visual stimuli are judged to be shorter than equal-length auditory stimuli. The reason behind this discrepancy is still subject to debate, however, one hypothesis is related to a theory about the internal representation of time. The model relies on an internal clock mechanism with a “pacemaker”, switch, and accumulator. While trying to keep track of the time the switch is flipped, the pacemaker ticks time by, and these ticks are summed in the accumulator. However, in this model, ticks accumulate more quickly for auditory stimuli than visual stimuli.
What brain regions underly systems of time perception?
One recent hypothesis links the perception of time with motor processes, as time perception provides important information on when and how to move. Functional magnetic resonance imaging (fMRI) acquired during visual and auditory rhythm tasks revealed temporal processing was associated with activity in premotor regions, the supplementary motor areas (SMA), as well as the basal ganglia. Regardless of the duration estimated, other studies have provided evidence for the role of the preSMA, the anterior cingulate cortex, the premotor cortex, and the basal ganglia. It’s also been suggested that activation of these regions measured with fMRI during time perception can be associated with different aspects of the internal clock, with the basal ganglia and SMA involved in time-keeping and more frontal regions recruited for attention, regardless of the task. Further, the insula is known to be involved in the emotional aspects of time-keeping and is thought to support the mediation between emotion and time perception.
What’s next?
Time perception begins at a young age, but the concept of external time is established over the span of childhood. As we age, how we perceive the passage of time continues to change. Lifestyle and life events can impact time perception, however more temporary changes, such as emotional state also impact how quickly time seems to pass. More research is needed to solidify theories surrounding time perception and to better determine causal links between our internal and external environments and how we perceive time. Further, research is needed to understand the real-world implications of how time perception can affect our everyday lives. Ultimately, time perception is a dynamic process that evolves and changes over the lifespan, and we still have a lot to learn about how the brain processes and experiences time.
