Five or six times a day, every day, for 48 years, chronobiologist Robert Sothern has counted off 60 seconds in his head and then compared the results against a clock.
As part of a lifelong experiment on circadian rhythms, Sothern, now 69, is trying to confirm or reject a widely held belief: Many people feel that time flies by more quickly as they age.
So far, Sothern's results are inconclusive. It's true that lately, according to his measurements — and his gut — time seems to be speeding up as he nears his 70s. "I'm tending now to overestimate the minute more than I used to," he tells me. But then again, he had detected a similar pattern — more overestimates — in the 1990s, only to have his estimates fall in the 2000s. "Time estimation isn't a perfect science," he says.
This matches what other researchers have found too. There's very little scientific evidence to suggest our perception of time changes as we age. And yet, we consistently report that the past felt longer — that time is flying by faster as we age. What's going on?
There are a few different ways to study how we perceive time. Scientists can look at time estimation, or our ability to estimate how long a minute passes, compared with a clock. (This is what Sothern is doing.) They can also look at time awareness, or the broad feeling that time is moving quickly or slowly. Finally there's time perspective, the sense of a past, present, and future as constructed by our memories.
What researchers have found out is that while time estimation and time awareness don't change much as we age, time perspective does. In other words: Our memories create the illusion time is accelerating.