You likely know from experience that human perceptions of time are not accurate. During a long, boring task, time feels like it plods along slowly; when we are experiencing excitement or joy, time flies by.

Psychologists have long studied our perception of time, with most of the research focusing on the brain. But a new study conducted by Cornell psychology researchers and published in the journal Psychophysiology earlier this year suggests that our perceptions of time at the millisecond level may be driven, at least in part, by our heartbeats.

In the study, Cornell researchers recruited nearly 40 undergraduate students and used electrocardiograms to precisely measure their heartbeats. Then researchers played audio tones for the participants and asked them to estimate the length of each tone. When participants had a slower heart rate they perceived the tones as longer, while with a faster heart rate, the tone was perceived as shorter.

An accurate perception of time
Sadeghi, a Cornell doctoral student and lead author of the study noted, “Your ability to perceive in the present moment will be different depending on your heart rate.” She said. “For example, when you are running so fast, and a flash of something appears, you may not perceive it as well as if you were calm. We think that’s because there are a lot of beats of the heart adding noise to your brain, so you’re not perceiving things happening around you as intensely.”

At the same time, the study found that a higher heart rate led to a more accurate perception of time. “People with higher heart rates tend to be more vigilant,” Sadeghi said. “More blood is reaching the organs and brain, so there are more resources available.”

Think back to the early days of humans; a higher heart rate likely meant running from trouble or chasing down food, two circumstances where vigilance would be important.

Looking at the whole body, not just the brain, to better understand perception is an emerging field in psychology, Sadeghi explained. “The heart is especially important because it is constantly pumping blood to the brain,” she said. “Other organs have interactions with the brain on a slower time scale, but the heart is on a very fast scale. Every beat is interacting with the brain.”

Between body and mind
Despite the groundbreaking results, the relationship between the heart and perception is not completely clear. “One possibility is heart rate is causing this effect, but there could be another shared factor that causes a change in heart rate and this effect,” Sadeghi said. “With our experiment, we concluded it’s probably a combination of both.”

The take-home message: New evidence suggests that your heart rate may influence your perception of time, opening up new avenues to understand the interplay between the human body and mind.