clocks in our heads
A Long Line for a Shorter Wait at the Supermarket - New York Times
“We have good clocks in our heads for roughly three minutes,” said Paco Underhill, founder of Envirosell, a retail consulting firm.
“Once we get beyond that, time expands wildly,” he said. “If somebody is there for 4.5 minutes and you ask them how long they waited, they will say 15 minutes.”
We do! Whether counting or not, most people are very good at estimating periods of 30 seconds and one minute. (I demonstrated this in 8th grade for the science fair.)