Time perception is linked with our experience of self

I’ve touched on why life feels faster with every year in an earlier newsletter, but the concept of time deserves some more attention.

To me, the felt experience of time is just as important as the science behind it. You need neuroscience AND philosophy to fully appreciate time - so I’ll bring in both.

Maria Popova’s Brain Pickings is among the highest quality online publications. With 13 years of content to draw from, newer articles always link out to older articles of hers that touch on the same topic. It’s a beautiful maze of thoughts to get lost in.

One way to understand time is through the lens of memory. Many people view memory as a recording device, but it’s really more of a tool to predict the future.

“We tend to think of memory as having primarily to do with the past… And maybe one reason we have it is so that we can have a warm feeling when we reminisce, and so on. But I think the thing that has been neglected is its role in allowing us to predict and simulate the future.” — Daniel Schacter

From a neuroscience perspective, there is actually significant overlap in the activity of the frontal and temporal lobes when thinking in either direction of time. One theory states that the concept of time helped early humans understand the continuity between the past and the future.

Beyond predicting the future, this continuity creates a sense of personal identity.

“The consciousness of time and consciousness of self co-create each other to construct our experience of who we are.”

Compared to sight or hearing, which are mediated by specific sense organs, the sense of time is felt in a more embodied way. Time perception is intimately connected to our experience of selfhood. This is abundantly clear when time perception is impaired in mental illnesses such as depression, addiction, and schizophrenia:

• With depression, the unpleasant sensation of time passing very slowly is heavily related to “negative self-image, self-blaming, and feelings of worthlessness”.
• With addiction, time becomes arrhythmic — flowing quickly under the influence and unbearably slowly during withdrawal. This focus on the present, with a dependency-free future seeming too distant, is the “temporal trap of addition”.
• With schizophrenia, the continuity of self (or the integration of past, present, and future) is disrupted. Many patients report time standing still.

For an extended discussion on time and self, check out the full article:

Neuropsychology of How Time Perception

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To compliment Popova’s philosophical discussion, the Brain Inspired podcast takes a more academic approach to time (and its applications in AI).

Although our man-made clocks robustly measure time across many different time frames (e.g. minutes, days, years), the brain has scale-specific clocks.

For example, we can tell that a sound is coming from the left because of the few milliseconds of delay before the sound wave reaches the right ear. The responsible circuit in our brain is sensitive on the scale of milliseconds, and it is fundamentally different from the circuit that underlies the circadian clock, which operates on the scale of days.

This is called the multiple clocks principle:

You brain has fundamentally different mechanisms to measure microseconds, seconds, hours, days, and so on.

We actually know very little about the circuits responsible for timing longer than a few milliseconds and shorter than a day. To better understand ourselves, we need to develop a taxonomy of time that details the mechanisms our brain uses at every scale.

For more, check out the rest of the conversation:

BI 018: Time in Brains and AI