There is no internal clock
How the brain perceives time
‘Time is very attractive, because it is very weird’, says cognitive-neuroscientist Nadine Schlichting. We all think we know what we mean when we talk about time passing; but in fact, the experience of time differs from culture to culture. While Westerners think of time as linear, the Japanese think of a timeline as a circle. The differences made Schlichting ask herself: is there any shared biological factor that helps us measure time?
It was a big question. ‘I wanted to know how time is represented in the brain. Looking back now, that was really naïve. But this sort of unrealistic enthusiasm may be exactly what PhD candidates need at the start of their long, bumpy journey’, Schlichting says. And even though she’s had many setbacks, last week she was finally be able to defend her thesis.
No brain clock
Her first experiments measured brain activity using EEG monitoring. Individual subjects were put in a room with a screen. The screen displayed some number of dots. During the first part of the experiment, subjects were instructed to focus on the number of dots. During the second half, they were told to simply focus on the passing of time.
The hope was that the brain activity recordings between the groups would be different. ‘That would indicate that the brain has designated special areas for processing time-related information’, she says.
But that’s not what happened. ‘I got really convincing null-results in the end: we definitely don’t have an internal clock-mechanism in our brains.’
Not a failure
At first Schlichting was disappointed. But looking back, she sees value in the results. ‘Null results are important results. I am not so bothered about finding nothing, because that already tells us something.’
And the experiments weren’t a total failure. She had to abandon her original hypothesis, but did find something interesting: when subjects focused on the number of dots on the screen, they seemed to perceive time differently depending on the number of dots displayed.
For example, a subject focused on a screen with four dots perceived time passing more slowly than a person focused on a screen with two dots. ‘That was weird. I decided to look into it.’
So she replicated the experiment. ‘On top of the effect I found, other studies report similar effects of other dimensions, like size and speed.’ Her results were clear: the higher the number, the faster time seems to pass. External input affects our perception of time duration.
Why does that matter? Well, we rely on external input to estimate time in our environments all the time. For example, if you see a ball coming at you from far away, you perceive that you will have more time to catch it than you would if it was thrown at you from a closer distance.
Schlichting’s experiments confirm that our cognitive processing works best if we ‘associate information about time with other input’. We need that input to make judgements about the passing of time precisely because we do not have a designated temporal sense or internal clock mechanism.
Schlichting hopes that the scientific community will distance itself from viewing time perception as an internal process and consider instead the many ways we extract information about time from different sources.
Her findings aren’t just an abstract scientific bauble, Schlichting says. The impact our environment has on time perception is something we can all consider and put to use in our daily lives.
In a chaotic environment, for example, we pay less attention to how much time is passing, whereas a less stimulating environment can have the effect of slowing down our perception of time passing. ‘In a cafe with a minimalist design, time will seem to slow. A busy, noisy cafe will probably have the opposite effect.’