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Pascal Mamassian, Andrei Gorea, Alan Johnston; Moving objects are perceived later. Journal of Vision 2007;7(9):379. doi: 10.1167/7.9.379.
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© ARVO (1962-2015); The Authors (2016-present)
Moving objects can generate various spatial illusions, such as the effect reported by DeValois and DeValois (1991) where the location of a stationary moving Gabor is misperceived in its direction of motion. One essential component of these illusions is some error in the time at which the moving object is perceived. We present here a method to measure the perceptual delay between moving and stationary objects. Observers were presented with Gabor patches that were modulated by a Gaussian window in both space and time. Two such Gabors were presented in succession and the observer had to estimate the time interval between them (in the order of 1 sec). The observer then had to press a key after a delay that was equal to the previously defined interval. One of the Gabors was stationary whereas the other was moving (drifting carrier at 5 deg/sec). We found that time intervals where the moving Gabor was presented first were systematically estimated to be shorter by about 80 msec compared to trials in which the static Gabor was presented first. In other words, moving Gabors were perceived to occur about 40 msec later than stationary ones. These results could appear counter-intuitive in face of physiological data showing that moving displays are processed faster than stationary ones. We discuss potential models that could account for this delay in perceived motion.
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