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Teresa Inoue, Ikuya Murakami; Apparent motion of a coherent and continuously moving random-dot pattern appears slower in update rate. Journal of Vision 2017;17(10):732. doi: 10.1167/17.10.732.
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© ARVO (1962-2015); The Authors (2016-present)
A moving stimulus appears to last longer than a static one (Brown, 1995). This perceptual time expansion depends on temporal statistics of stimuli (Kanai, et al., 2006; Kaneko & Murakami, 2009). Recently, Inoue, Itoi, and Murakami (ICP 2016) reported a related but new time illusion. A random-dot pattern moved coherently in the same direction across multiple frames ("Coh"), moved coherently but in a random direction every frame ("CohRand"), or was refreshed to a new pattern every frame ("Rand"). The frame update rate was 6.7 Hz. Participants matched a train of periodical click sounds to the perceived rate of frame update. It was found that the perceived update rate in the Coh condition was slower than others. The present study attempted to extend this previous report by examining the above illusion over a range of jump sizes between succeeding frames while introducing more stringent controls in stimulus parameters, such as fixation maintenance during each trial, avoidance of optokinetic nystagmus, and setting a focus on the update rate per se rather than the duration. We provided a fixation point throughout each trial and simultaneously presented a moving pattern in one hemifield and its rotation-symmetrical version in the other hemifield to discourage reflexive eye movement. These visual patterns were displayed for an interval shaped by a blurred temporal window and were followed by a train of click sounds. In a two-alternative forced-choice paradigm with the method of constant stimuli, participants reported which one appeared to be updated faster, the visual pattern or click sounds. The results indicated that perceived update rate was slowest in the Coh condition and fastest in the Rand condition. In addition, the shorter the jump size was, the stronger the illusion. The results will be discussed in relation to costs of smooth scene maintenance and abrupt scene update.
Meeting abstract presented at VSS 2017
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