Brightness function: Role of the pupil

Pairs of brightness functions were generated by magnitude estimation, one pair for each of three flash durations (0.5,1.0, and 3.0 sec). Each pair comprised a function obtained with an artificial pupil and a function obtained with the uncontrolled natural pupil. The pupil turned out to have little or no effect on the form and slope of the power functions for brightness, even when flash duration was as long as 3.0 sec.