Outlined and filled distracters in the visual illusions of the Brentano type A Gutauskas, A Bulatov, N Bulatova |
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Institute of Biological Systems, Lithuanian University of Health Sciences, Lithuania
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| It is known that early visual processing is accompanied by the effects of contour extraction which occurs due to spatial frequency filtering possessing the properties of 2D second derivative (the Laplacian operator). Therefore, the filtering should strengthen the similarity of excitation profiles evoked by the outlined or filled contextual objects having the same shape, and one can expect that applying of these different distracters in length-matching tasks should cause approximately the same illusory effects. In order to check this prediction, the psychophysical study with stimuli comprising three circular sectors arranged according to ordinary Brentano pattern, has been performed; the radius of the sectors was used as the independent variable. As it was expected, the experiments with different distracters (either the outlined or uniformly filled) yielded similar results, and the shape of the experimental curves can be completely explained by our model of automatic centroid extraction [Bulatov et al, 2009, Acta Neurobiologiae Experimentalis, 69 (4), 504-525]. |
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