Preparatory state effects in intersensory facilitation

Four trained Ss participated in a task concerned with intersensory facilitation of reaction time (RT). Discriminative RT to a visual event was longer than discriminative RT to a combined auditory-visual event, even though the auditory event by itself was a catch signal. The magnitude of this difference was greater with a long (5.5 sec) as opposed to short (.5 sec) foreperiod delay. This finding supported the hypothesis that the auditory component of the combined event serves a preparatory state role by enhancing response readiness, a role that is manifest to the extent that S’s prior degree of preparation is nonoptimal.