The two-flash threshold: An evaluation of critical-duration and visual-persistence hypotheses

Abstract

The two-flash threshold is reduced by increasing the duration of both pulses of light or light adapting the eye. Increasing the duration of the first pulse also decreases the two-flash threshold, contrary to what a critical-duration explanation of the threshold would predict. Decreasing the duration of the second pulse increases the threshold when the second pulse is very brief. Light adapting the eye under such conditions serves to increase the two-flash threshold, unlike the effect adaptation has when a long second pulse is used. © 1971 Psychonomic Society, Inc.