Time flies when you’re having fun, but why is that? A new study by researchers at the University of Nevada, Las Vegas (UNLV) offers intriguing insight into how our brains perceive the passage of time.

Some of us believe that our brains track time in sync with the clocks on our devices, counting each second as it passes. However, that’s not exactly right. The new study suggests that our perception of time is actually based on our experiences rather than a precise internal clock.

Understanding the Brain’s Perception of Time

Researchers analyzed brain activity patterns and discovered that the number of experiences we have influences our perception of time. Performing an activity faster also affects how our brains register the passage of time.

“We tell time in our own experience by things we do, things that happen to us,” explained James Hyman, associate professor of psychology and the study’s senior author. “When we’re still and we’re bored, time goes very slowly because we’re not doing anything or nothing is happening. On the contrary, when a lot of events happen, each one of those activities is advancing our brains forward. And if this is how our brains objectively tell time, then the more that we do and the more that happens to us, the faster time goes.”

The study used brain scans that zoomed in on the anterior cingulate cortex (ACC), a brain region critical for monitoring activity and tracking experiences. Researchers tasked rodents with performing repetitive motions and analyzed their brain patterns. Some of the rodents had to respond to the same prompt over 200 times.

The researchers already knew from previous studies that each time we do a repetitive motion, the brain patterns are similar, but not exactly so — they’re always slightly different. The big question on the study authors’ minds was whether these slight differences in brain pattern changes correspond with doing the first versus 200th motion in a series.

A feeling about time

The results showed that the brain’s activity changes detectably as a task progresses, from beginning to end, regardless of the speed of motion. These patterns remained consistent when analyzed with a machine learning model, indicating that experiences, not time intervals, drive changes in neuronal activity.

Hyman illustrated this with a hypothetical example of two factory workers tasked with making 100 widgets. One takes 30 minutes to complete the task while the other needs 90 minutes.

“The length of time it took to complete the task didn’t impact the brain patterns. The brain is not a clock; it acts like a counter,” Hyman explained. “Our brains register a vibe, a feeling about time. . . And what that means for our workers making widgets is that you can tell the difference between making widget No. 85 and widget No. 60, but not necessarily between No. 85 and No. 88.”

The findings suggest practical applications for managing time perception in daily life. For instance, if we want to remember something, we may benefit from slowing down and taking breaks between activities. Conversely, engaging in activities right away and at a fast pace could help us perceive an activity passing faster.

“The more we do, the faster time moves. They say that time flies when you’re having fun. As opposed to having fun, maybe it should be ‘time flies when you’re doing a lot’,” Hyman said.

Time scales in the ACC

This study is among the first to examine behavioral time scales in the ACC, a brain region linked to various psychiatric and neurodegenerative disorders. The ACC has long been associated with helping humans with sequencing events or tasks such as following recipes. And the researchers believe their findings about how we perceive the passage of time could offer insights into conditions like Alzheimer’s disease, where time perception is often distorted.

“This is the part of the brain we use for tracking something like a conversation through dinner,” Hyman said. “Think of the flow of conversation and you can recall things earlier and later in the dinner. But to pick apart one sentence from the next in your memory, it’s impossible. But you know you talked about one topic at the start, another topic during dessert, and another at the end.”

Ultimately, understanding the brain’s perception of time can empower individuals to manage their mental health by viewing time perception as a physical process.

“When things move faster, we tend to think it’s more fun — or sometimes overwhelming. But we don’t need to think of it as being a purely psychological experience, as fun or overwhelming; rather, if you view it as a physical process, it can be helpful,” he said. “If it’s overwhelming, slow down or if you’re bored, add activities. People already do this, but it’s empowering to know it’s a way to work your own mental health, since our brains are working like this already.”

The findings appeared in the journal Current Biology.