Have attention spans been declining?
I'd measure attention span by the length of time one can dedicate to a task one enjoys during the day.
It would be entertaining maybe to compare high school automechanics programs over years, for instance, as one learning culture.<p>Btw, I wouldn't be shocked if it found our attention spans are fine, what we're dealing with is environments that are getting harder and harder to do sustained activities within - because so many different demands on attention are going on all the time.