京都大学21世紀COEプログラム Bチーム特別講演会

講演者：　Professor Philip M Grove

演題：Ecological considerations about audio-visual events in 3-D space

　　　（3次元空間内での聴覚-視覚的イベントに関する生態学的考察）

日時：3月4日(土)　12:30-13:30

場所：京都大学文学部 新第3講義室

概要：

In my talk, I will discuss some recent experiments investigating how an auditory stimulus can affect the perceived 2-D and 3-D trajectory of two moving visual targets. Consider two identical discs moving from opposite sides of a 2-D display towards each other at a constant speed.　 When they meet in the middle of the display, they overlap and then subsequently continue their trajectories to the opposite sides of the display.　 Because the discs are indistinguishable and they superimpose at the mid-point in their trajectory, the retinal images are equally consistent with two mutually exclusive events.　 One event is that after the discs were superimposed, they continued on their original path to the other side of the display.　 Another possible event is that after the point of coincidence the discs reversed their directions.　 In the first case, the discs would be said to “stream” passed one another.　 In the latter case the discs are said to “bounce” off of one another.　 It has been reported that streaming is the dominant perception in the scenario just described (Bertenthal, Banton & Bradbury, 1993; Sekuler, Sekuler & Lau, 1997, Watanabe & Shimojo, 2001).　 Sekuler et al. (1997) report an interesting cross-modal interaction between vision and audition in which a transient stimulus, such as a brief tone presented at or close to the exact moment the two identical discs are superimposed, biases the dominant perception from streaming to bouncing.　 Little is known about how inputs from different senses, such as vision and audition, are coordinated.　 This relatively recent discovery presents us with the opportunity to systematically investigate how the human perceptual system integrates information from different sources in order to arrive at a certain outcome.　 We evaluated the conditions under which an auditory stimulus affects visual perception in motion displays.　 The optimal conditions for auditory-visual interaction in these displays are assumed to be when the targets have identical color/texture and their relative 2-D and 3-D positions at the point of coincidence/contact are consistent with a collision. It is unknown whether an auditory stimulus will bias the perception of a motion display in which these optimal conditions are not met. Our data show that an appropriately timed auditory stimulus is perceptually powerful enough to elicit the perception of a collision even when the visual information is inconsistent with such an event.　 Furthermore, contingent with a bounce perception 2-D and/or 3-D trajectories of the moving targets that are physically inconsistent with a collision were perceptually altered to make them consistent with a collision event.　

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