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Bettina Friedrich, Maria Hadjigeorgieva, Pascal Mamassian; Attentional effects and motion-induced masking. Journal of Vision 2003;3(9):794. doi: 10.1167/3.9.794.
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© ARVO (1962-2015); The Authors (2016-present)
The position of a moving object can be perceived shifted in the direction of motion when its edge is equiluminious (Ramachandran & Antis, 1990; De Valois & De Valois, 1991; Whitney, 2002). Mamassian and Adams (VSS 2002) tested whether this would lead to a masking effect, i.e. if a target positioned directly in front of a moving object would be more difficult to detect as it is masked by the motion. This could not be shown consistently. We examine here whether this previous result can be explained by competing attentional effects to the front side of the moving object by using attentional cues in order to control the allocation of attention. Four grating motion fields modulated by stationary Gaussian envelopes (Gabors) were presented around a fixation cross. A target was presented next to one moving Gabor and observers had to report its polarity (dark vs. bright). Before the onset of the trial, the location of the target was hinted by a cue which was valid 75% of the time. As expected, the valid cues led to better discrimination of the stimulus than invalid cues did. After invalid cueing, targets were consistently better discriminated when they appeared behind rather than in front of the moving Gabor. Our results suggest that failures to find a masking effect can be due to more attention being allocated to the front of the moving object. When attention was drawn away from the moving object, a motion-induced masking effect appeared consistently.
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