Heartbeats can shape our perception of time – 03/17/2023 – Science

It is an indisputable truth that time seems to expand or contract depending on the circumstances in which we find ourselves: when we are in a state of terror, the seconds seem to stretch out. A day spent in isolation can take a while to pass. When we’re trying to meet a deadline, the hours fly by.

A study published this month by psychologists at Cornell University in the journal Psychophysiology found that, when looked at at the microsecond level, some of these distortions can be caused by heartbeats, whose duration varies from moment to moment.

Psychologists took electrocardiograms of college students to accurately measure the duration of each heartbeat and then asked them to estimate the duration of brief audio tones. They found that after a longer heartbeat interval, students tended to perceive the sound as being shorter. Shorter intervals led them to evaluate the sound as having a shorter duration. After each sound, the participants’ heartbeat intervals increased.

A lower heart rate seemed to help with perception, said Saeedeh Sadeghi, a Cornell University doctoral candidate and lead author of the study. “When we need to pick up things from the outside world, the heartbeat is picked up by the cortex as noise,” she said. “It’s easier to apprehend things that come from outside when the heart is silent.”

After an era of research that focused on the brain, the study provides further evidence that, according to Sadeghi, there is no isolated part of the brain or body that keeps time – it’s an entire network. “The brain controls the heart, and the heart in turn impacts the brain.”

Interest in the perception of time has greatly increased since the Covid pandemic, when activities outside the home suddenly ceased for many, and people around the world had to face long periods of undifferentiated time.

A study of time perception conducted in the first year of the UK lockdown revealed that 80% of participants reported time distortions in different directions. Overall, older and more socially isolated people reported that time passed more slowly, while younger and more active people reported that time sped up.

“Our experience of time is affected in ways that broadly mirror our well-being,” said Ruth S. Ogden, professor of psychology at Liverpool John Moores University and author of the lockdown study. “People with depression experience time passing more slowly, and this slowing down of time is perceived as a factor that aggravates depression.”

The new study from Cornell University focuses on something different: how we perceive the passage of microseconds. Understanding these mechanisms can help us manage trauma, in which flash experiences are remembered as having lasted longer, Ogden said.

According to her, when our brain tries to evaluate the importance of a lived experience, “it looks back and asks: ‘How many memories did we create?'”. He added: “When you have a really strong, denser memory than you normally would of a 15-minute period of your life, it will fool you into thinking it took longer.”

Until recently, research on time perception has focused on areas of the brain, said Hugo Critchley, a professor of psychiatry at Brighton and Sussex Medical School who has studied how the heartbeat affects word memory and fear responses.

“I think there’s a much greater appreciation that cognitive functions are intimately linked to, possibly grounded in, body control, whereas most psychological theories up until the 1990s dismissed the body as something controlled at the brainstem level.” , said Critchley, who was not involved in the Cornell University study of heartbeats.

Previous research has investigated how physical alertness is linked to processing stress and emotional states like anxiety and panic, Critchley said. The new study expands on this by focusing on the heart’s role in a non-emotional function, time perception, which can be linked to larger distortions in thinking.

“You can’t look at cognitive function in isolation,” he said. “Even understanding how the brain develops and begins to represent inner mental states, people still look to the primacy of inescapable inner information that you need to control to stay alive.”

One reason the body may be intimately involved with the perception of time is that time is closely linked to metabolic needs, said Cornell University psychology professor Adam K. Anderson, co-author of the new study.

“Time is a resource,” Anderson said. “Whether the body is a battery or a fuel tank, it’s trying to ask right now, ‘How much energy do we have left?’ Let’s try to make things seem shorter or longer in terms of time, based on how much body energy we have.”

^{Translated by Clara Allain}