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A. S. Del Vecchio, M. W. Grunau, J. Faubert; Attentional selection of first- and second-order motion stimuli. Journal of Vision 2001;1(3):88. doi: 10.1167/1.3.88.
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© ARVO (1962-2015); The Authors (2016-present)
It has been shown that selectively attending to one component of a complex moving stimulus, a plaid for instance, enhances the duration of the motion aftereffect (MAE) as compared to the unattended component MAEs. This was true whether the participants adapted to a first- or a second-order stimulus. In the present study, the effect of selective attention during the adaptation to plaids on the duration of the MAE with a dynamic test stimulus was investigated using complex motion stimuli composed of two spatially superimposed, but temporally alternating square-wave gratings differing by 310 degrees in motion direction. The complex motion stimuli consisted of either: 1) two first order, luminance-defined, gratings, 2) two second-order, texture-defined, gratings, and 3) a mixture of first-order and second-order gratings. In contrast to previous studies, the first-order component contained noise to make it more similar to the second-order grating. Furthermore, the components were made easier to select and attend by using square-wave gratings with a larger angular difference and by using smoother motion sequences. The sensitivity to the first- and second-order gratings was matched for each participant by adjusting the luminance of the first-order component to cancel the second-order motion in the opposite direction. Results suggest that selective attention to second-order stimuli is much harder to maintain due to ambiguous depth relations between the components. Nonetheless, attending to one component during adaptation increases the duration of the MAE for all types of motion stimuli, but suppression of the unattended component in terms of MAE is restricted to first-order components.
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