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Armand R. Tanguay, Noelle R. B. Stiles, Ishani Ganguly, Shinsuke Shimojo; Time Dependence of Predictive and Postdictive Auditory-Visual Processing: The Temporally Extended Audiovisual Rabbit Illusion. Journal of Vision 2019;19(10):19b. doi: https://doi.org/10.1167/19.10.19b.
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© ARVO (1962-2015); The Authors (2016-present)
Background: Postdiction occurs when a later stimulus influences the perception of an earlier stimulus. The Audiovisual Rabbit illusions (Stiles, 2018) demonstrate that postdictive processing bridges multiple senses. When a beep-flash, beep, beep-flash sequence was presented with the second flash displaced laterally, participants perceived three flashes (one illusory), with the illusory flash postdictively shifted toward the final flash. In this experiment, we extended the time between the second beep and the final beep-flash pair by either 100, 300, 500, 700, or 900 ms to determine the time dependence of postdiction (Experiment 1). Furthermore, we determined the predictive influence on flash location by extending the time between the first beep-flash pair and the second beep/third beep-flash pair by either 100, 300, 500, 700, or 900 ms (Experiment 2). Methods: The Audiovisual Rabbit illusion was tested with two flashes (17 ms each) presented at a 10° eccentricity (below fixation) with apparent left-to-right or right-to-left horizontal motion, randomly ordered. The first and second flashes were paired with 7 ms beeps, with an additional beep but no flash in between. Participants reported the number of flashes perceived and their locations. Results: Participants (N = 6) reported a decreasing shift of the illusory flash toward the first beep-flash pair (Experiment 1, Postdiction), and a decreasing shift of the illusory flash toward the final beep-flash pair (Experiment 2, Prediction) as the time delay increased. Both postdictive and predictive shifts were significant, and for some participants extended over the entire range of time delays tested. Postdiction significantly shifted the illusory flash toward the final flash for time delays up to at least 500 ms. Discussion: These experiments provide a comparison of the predictive and postdictive time dependencies and relative influences within the Audiovisual Rabbit Illusion, and therefore constrain the neural models that describe predictive and postdictive crossmodal behavior.
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