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Yutaka Nakajima, Takao Sato; The involvement of local motion adaptation in global motion aftereffect. Journal of Vision 2008;8(6):1036. doi: 10.1167/8.6.1036.
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© ARVO (1962-2015); The Authors (2016-present)
Bex, Metha & Makous (1999) have reported that adaptation to a circular global motion generated by four Gabor patches induce a global motion aftereffect (MAE) in four Gabor test-patches located in-between adaptation patches. However, these results could result from a spillover of local motion energy or existence of motion receptive fields much larger than the adapting and test patches. In order to test this possibility, in this study, we varied the number of test patches and compared the duration of MAE. The adaptation stimulus was an array of four Gabor patches similar to Bex et al., and one, four, and eight test patches were used. The patches in the one- and four-patch conditions overlapped with those of adapting patches. In eight-patch condition, four patches overlap with the adaptor but the other four were placed at in-between positions. It was found that MAE in the four-patch condition was strongest. The result that MAE is stronger in the four- than in the eight-patch condition strongly argues that the global MAE reported by Bex et al. was really a global MAE, since if it was caused by a spillover or large RFs, the eight-patch condition in this study should produce stronger MAE than the four-patch condition. The efficiency in tapping the global MAE should be higher with eight patches. When eight patches were used in adaptation and MAE was tested by four and eight patches, eight patches produced stronger MAE. Thus, the reduction in the eight-patch condition in the four-patch experiment was probably caused by some inhibitory or subtractive process when local, component MAEs are integrated. These results, therefore, suggest that global MAE has two components. One is caused by adaptation of a high-level global motion mechanism, and the other comes from reorganization of low-level local MAE.
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