Time is elastic, especially on the subway. This is the conclusion reached by a team of researchers from Cornell University in New York after conducting an unprecedented experiment using virtual reality. For their study, published in the scientific journal Virtual reality on November 3, 2022, American researchers placed about forty subjects in a fictitious New York subway. They reproduced five situations where the train was more or less crowded. These ranged from 35 to 175 avatars behaving like real passengers. They can read or look at their phone for example. Participants began rides of random duration between 60 and 80 seconds. After each trip, the researchers asked their subjects whether they found the trip enjoyable on a scale of 1 to 7, and to rate the length of their trip.
“Crowds give a sense of stress that makes the journey seem longer”
It turned out that when the number of passengers became very large, the subjects of the experiment overestimated their travel time on the subway. More specifically, when the train was particularly crowded, the travel time appeared to be 10% longer than that spent on a subway where few individuals had gathered. The difference amounts to 20% between the train with 175 passengers and the one with only 35. To explain this difference, the researchers relied on their questionnaire about the satisfaction of the experience for the participants. They observed that the more unpleasant the trip, the stronger the temporal bias. “The crowd gives a sense of stress that makes the journey seem longer” says Saeedeh Sadeghi, co-author of the study with Cornell Chronicle news site.
Emotions at the heart of our internal clock
Many scientific papers have already shown the importance of emotions in our perception of time or rather our own “The subjective judgment of time”. “This experience is based on a posteriori evaluation, we reconstruct our idea of the passage of time according to other factors, for example after a boring meeting, we will have the impression that time has been long. We express ourselves with feelings.” , explains Sylvie Droit-Volet, professor in the social and cognitive psychology laboratory at Clermont Auvergne University, in Science and the future. There is also a physiological dimension, which is immediate, relative to the hourglass. When we are in certain emotional states such as joy or fearOur internal clock changes its rhythm according to the rhythm of the heart and muscle contractions and gives the impression that time passes more or less quickly. “This way of perceiving durations is not unique to adults, we have observed these time biases in infants and even in mice.” says the researcher. In their study, the American scientists were also interested in the heart rate, but did not show any significant difference between a situation where the subway is sparsely populated and one where it is full of people. Thus, crowd-induced stress does not appear to affect passengers’ relationship with time during their metropolitan epic. It seems more likely that it is the fact that you feel it that gives you the impression that the journey was unpleasant and therefore long.
Brain, a watch like no other
“The whole brain is predisposed to estimate time in very short periods thanks to cortical oscillators found throughout the cerebral cortex. (outer brain, editor’s note)“ Sylvie explains to Droit-Volet Science and the future. Cortical oscillators create a kind of time code that is translated by neurons in the striatum (the inner part of the brain, editor’s note) for already memorized durations. This is why the perception of time is refined with age.
For stimuli of several milliseconds, it is the cerebellum that serves as the decoder, and the prefrontal cortex makes it possible to estimate durations. The brain is therefore subjected to multiple temporal stimuli that cause the activation of many different neuronal areas. Thus, the more stimuli there are from the internal and external environments, the more cortical oscillators will be active and, like a cerebral metronome, these will increase the speed at which the brain processes information, which will give the feeling that time is shorter. . That’s why when we’re doing an activity we enjoy, time goes by faster, and when we’re depressed, everything seems longer. Our internal clock has extremely complex cogs involving thousands of neurons and all the mechanisms are still not well understood. However, scientists hope to use it to understand us better. “Researchers are currently working on an analysis of temporal brain perception to diagnose depressive states”. notes the professor of social and cognitive psychology.
A relationship with time that varies between each individual
A feeling that can vary from person to person. This can be different between a person accustomed to these urban journeys and an individual who is not familiar with them. “In general, new experiences seem longer than repeated ones. There is a phenomenon called “return trip effect”, that going to a destination seems longer than coming back, even if the distances are exactly the same. This is because the return journey is more familiar and therefore seems shorter. It’s the same for people who are used to taking the subway every day, we can expect the journeys to seem shorter for those who take the subway every day.” assumes Saeedeh Sadeghi.
Researchers are concerned about the potential environmental impact
Despite potential resilience on the part of travelers, the research team is concerned about the detrimental effects of these extended journeys. According to an Ipsos poll, carried out in January 2022, the French spend almost 50 minutes a day in transport and 12% of them travel by metro. Based on the results of the study, this makes almost 4 hours of travel felt more every year on the subway. If we take the scenario with a particularly crowded train, this duration increases to 8 hours, i.e. an extra working day.
Especially since the pandemic may have emphasized this effect. “During the pandemic, social distancing guidelines have constantly reminded us of the threat of crowds. So, over the past couple of years, our brains have been trained to be even more protective of crowds. With the increased discomfort caused by the crowd after the Covid crisis, we expect the metro travel time to feel even longer.” explains Saeedeh Sadeghi who conducted this experiment in 2019. In the columns of the Cornell Chronicle news site, the researchers specify that this feeling can lead certain users to use their car instead of public transport. This would cause more pollution in an atmosphere already saturated with CO2. “We have to make the journey more enjoyable! Our results showed that it’s not the clutter itself, but the stress it creates, that makes a journey seem longer. We could, for example, put bigger windows on trains to alleviate, to some extent, the unpleasant feeling of being overwhelmed by the crowd.” suggests the co-author of the study.
A promising but limited experience
Despite its innovative side with the use of virtual reality to reproduce conditions closer to everyday life, this study has a number of limitations. They are both technical and experimental. “Even though our simulation is very realistic, avatars still look different from real individuals. Furthermore, the participants of the experiment had only to imagine that they were going to a destination, but they were physically in the experiment room located in a building on the university campus. notes the Cornell researcher about it Science and the future.
In order to have more convincing results, he believes that a more photorealistic experience should be carried out, to which stimuli affecting the 5 senses would be added to simulate a crowd in the most accurate way possible. This experience also lacks many factors that can modify the perception of time. “We need to go further, for example by looking at the types of people present in transport. Do we have the same perception of the durations when the subway is full of children or the elderly? And if a woman is surrounded by men on a train, could her possible sense of insecurity modify her relationship with time? A more psychosocial approach is needed. Of course there are many inter-individual factors to be evaluated”. points out Sylvie Droit-Volet. “This study is original and allows us to bring everyday life into our laboratories. At the moment, this is insufficient. This is a first study, but using virtual reality is a good way to approach the complexities of everyday life. This is the next step in psychosocial studies. concludes the professor of social and cognitive psychology.