Audiovisual integration and incidental learning

7 Temporal or spatial correspondence between multisensory signals usually aids perception, memory and learning, but we demonstrate one way in which such correspondence has an opposite, disruptive effect. Stimuli were eightitem sequences in which varying luminances and frequencies were presented concurrently and rapidly (at 8 Hz). Subjects tried to ignore the auditory component of each concurrent sequence, judging only whether the final four items in the accompanying visual sequence identically replicated the first four items. Each sequence’s luminances and frequencies were either perceptually correlated (Congruent) or were randomly related to one another (Incongruent). Experiment One showed that despite encouragement to ignore the auditory stream, what subjects saw was strongly influenced by what they heard. Moreover, the extent of this influence tracked the similarity between a sequence’s separate audio and visual components, revealing that the task-irrelevant auditory sequences had undergone a considerable degree of processing. Using a variant of Hebb’s repetition design, Experiment Two compared musically-trained subjects and subjects who had little or no musical training on the same task as used in Experiment One. Test sequences included some that intermittently and randomly recurred. The auditory component of an audiovisual sequence influenced musically-trained subjects more than it did other subjects. Moreover, recurring sequences produced better performance than sequences that were generated anew for each trial. This result demonstrates that sequence-selective, task-irrelevant learning of sequences can occur even when sequences comprise non-distinctive, homogenous components. (Word count = 7500)