Test of the hypothesis of psychological refractory period.

Abstract

An experiment was performed to test the hypothesis of psychological refractory period that is offered to account for the established finding that response to the second of two closely spaced stimuli shows decrement. One line of explanation argues for a central decision time, where time must be allowed for processing the first stimulus and response before the second sequence can be undertaken. A competing explanation is the expectancy hypothesis which ascribes decrement to S''s past experience with the random array of interstimulus intervals that is usually used in experiments on this topic. Through practice, S comes to expect a longer delay and the decrement is because he is not optimally ready to respond. The experiment involved a two-dimensional, bisensory discrete tracking task. The statistical structure of interstimulus time intervals was the experimental variable aimed towards discriminating between the two hypotheses by asking if decrement could be a function of the temporal organization of stimuli. The results supported the expectancy hypothesis. Reliably less decrement was found for Ss who trained on a stimulus series with a predominance of small time intervals and could learn behavior appropriate to them.