The persistence of psychological refractoriness

The view that psychological refractoriness is a fundamental characteristic of human performance was supported by its survival of a determined attempt to eliminate it through training. An S was given practice for 87 days on a successive choice-response task with a constant inter-signal interval of 100 msec. Although his performance became better than any exhibited by Ss with more typical practice, he was not able to reduce psychological refractoriness to less than 20 or 25 msec. Moreover, when S was then shifted to variable inter-signal intervals he showed greater than the usual amount of psychological refractoriness at the intervals next longer than 100 msec. This indicated that he had learned a special skill rather than a generally "less refractory" mode of response (or merely better technique on the separate tasks). Training was found to be an effective way of eliminating holding back on the first response.