It's an actual study that was done recently by a company, and lead to the discovery that people are horrible at estimating how much time they spend doing things and typically under-estimate the time more than over-estimate. What is a "split second" could be 2 seconds, which is a massive amount of time at 7m/s. That's 14 meters, almost 3 car lengths.

These small one or two second errors in measuring time mean something to the discussion. A half a second means something to this discussion.