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David Whitney; Visual motion shifts perceived position without awareness of the motion. Journal of Vision 2005;5(8):225. doi: 10.1167/5.8.225.
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© ARVO (1962-2015); The Authors (2016-present)
A number of striking illusions show that visual motion influences perceived position. While most of these demonstrations have used luminance defined motion, presumably detected by passive motion processing units, more recent demonstrations have shown that it may not be the physical or retinal motion that matters: the perception or awareness of motion may actually determine perceived position (Shim & Cavanagh, 2004; Watanabe, et al., 2002, 2003). In fact, all motion-induced position shifts may be a product of higher level mechanisms like inferred motion or attentive tracking—processes that require an awareness of motion. To test whether an awareness of motion is necessary to shift the perceived positions of stationary objects, subjects adapted to a moving pattern in a crowded scene filled with other moving patterns; because of the crowding, subjects could not identify the direction of motion in the adaptation pattern. Following adaptation, when a single static test stimulus was presented within the adapted location, subjects perceived the test stimulus to be shifted in position. Even when the test stimulus did not display a motion aftereffect, it still appeared shifted in position due to the previous motion that subjects were not aware of. The results suggest that awareness of motion is not necessary to shift the positions of stationary objects, and that there must be a contribution of passive, bottom-up motion detection mechanisms to perceived position.
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