Intersensory effects in the psychological refractory period

Two experiments examined reaction time (RT) to each of two stimulus events separated by short interstimulus intervals (1SI). The essential contrast was RT to the second visual signal, RT ₂, in auditory-visual (A-V) vs visual-visual (V-V) sequences. With response, certain pairings in Experiment 1, an effect apparently demonstrating a single-channel process (Welford, 1952), was noted. RT ₂ was generally faster for A-V as opposed to V-V sequences especially when Ss were uncertain as to the sequence that would occur. At 0-msec ISI, the RT ₂ difference between sequences approached the RT! difference. More rapid RT ₂ to A-V sequences was also observed with go vs no-go pairings in Experiment 2 when the initial event was a go signal. However, the RT difference disappeared upon error correction, making the RT ₂ sequence difference of questionable relevance to the hypothetical single-channel process. RT ₂ was more rapid following a null no-go signal when the no-go signal was contrasted with a visual as opposed to auditory go signal. The latter effect was independent of error and is consistent with channel-switching theory (Kristofferson, 1967).