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Philip Grove, Kenzo Sakurai; Equivalent stream/bounce effects in cyclopean and luminance defined displays. Journal of Vision 2007;7(9):302. doi: https://doi.org/10.1167/7.9.302.
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© ARVO (1962-2015); The Authors (2016-present)
When two objects move towards each other, coincide, then move away from each other, two possible perceptions can result: the objects can be seen to stream past one another or to bounce off of one another. In visual only displays, the predominant perception is streaming. If, however, a brief auditory stimulus is presented at or near the point of coincidence, the bias towards streaming is reversed and bouncing is predominantly reported. To the best of our knowledge, all previous studies on this phenomenon have employed luminance-defined motion displays (i.e. black discs or blocks on a light background). Here we show using dynamic random dot stereograms that stream/bounce audio-visual interactions are similar for luminance-defined and cyclopean displays. Observers viewed both types motion sequences (frame rate = 20Hz) in the presence or absence of a brief auditory tone. When present, the tone occurred 0, 100 or 250 ms before or after coincidence. At the end of each sequence observers indicated whether the targets appeared to stream past or bounce off of one another. Stimuli were presented 20 times each in random order. The presence of an auditory tone at or before the point of coincidence significantly promoted bounce perception in both cyclopean and luminance defined displays. Auditory tones presented 250 ms after coincidence failed to promote bouncing in luminance defined displays but continued to do so in cyclopean displays. Nevertheless, the pattern of responses was strikingly similar in both types of displays. Control experiments manipulating the duration of the post coincidence trajectory yielded virtually identical results for both display types and do not support a cognitive-bias explanation of the auditory induced bounce bias. Our data show, as has been previously conjectured, that auditory and visual cues are integrated to resolve stream/bounce motion displays at or beyond the point of binocular combination.
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