The just noticeable difference

That summer that I was ten -

Can it be only one

summer that I was ten?

May Swenson – The Centaur [1958]

We all say that as we age, time seems to pass more quickly. There exists in the human sciences a name for that phenomenon. It's called the just noticeable difference, and it extends to all of our senses. The jnd, as it's called in the jargon, can be quantified and calculated empirically.

T...