The effect of varying information on the psychological refractory period

Abstract The two main theories of the psychological refractory period, single-channel theory and expectancy theory, make different predictions about the expected delay in RT2 as a function of the time required to select the first response. According to a single-channel theory, delays in RT2 should be proportional to the time required for RT1, while an expectancy theory predicts that RT2 is influenced only by range of ISIs employed, and should not change with changes in RT1. By varying the number of alternatives associated with the first response, it was found that delays in a two-choice verbal RT2 increased with increasing number of alternatives of RT1, supporting the prediction of the single-channel model. In a second experiment the influence of varying information of RT2 on the latency of RT1 was examined and it was found that latency of RT1 increased as the number of alternatives of the second response was increased. A third experiment was therefore done to determine whether the delay in RT1 was due merely to a change in set, or to an increase in amount of attention required to keep the second signal in store. It was found that corresponding increases were not found on trials where S was expecting the second signal but it was not presented, thus suggesting that some channel capacity is required for the maintenance of the second signal.