Abstract
Typical developing human brains automatically integrate information from different sensory modalities. Particularly, audiovisual integration plays an important role. To examine this interaction, two additional variables, frequency difference and modulation depth, were added to the original Fish Police!! game. In this game, temporal correlation between visual and auditory stimuli was manipulated. More specifically, subjects were presented with swimming fish whose size oscillated and sound signals whose amplitude oscillated. The task was to categorize each fish as fast or slow-oscillating fish, while trying to disregard an irrelevant concurrent broadband sound signal. Different frequency differences and modulation depths were integrated into Experiment One and Two, respectively. Both experiments showed that when visual and auditory oscillation frequencies match (congruent), categorization was faster and more accurate, whereas when frequencies mismatch (incongruent), categorization was slower and less accurate as compared to the control, where the amplitude of the sound signal was unmodulated. Frequency difference influenced performance in terms of speed and accuracy by altering difficulty, but it did not interact with congruence condition. Modulation depth also influenced performance, mainly incongruent trials. Finally, results suggested that subjects were using contextual information about frequency difference and modulation depth of each block to make decisions.