Abstract
Introduction: Motion-induced blindness (MIB) is the perceptual phenomenon whereby stationary peripheral targets disappear when presented with a moving mask. It has been proposed that MIB is mediated by competitive local interactions between the target and mask. To evaluate this account, we introduced displays in which motion properties of the mask were systematically altered in spatially confined regions of the display (i.e., surrounding the target location or elsewhere). Specifically, these regions contained incoherent motion while the remainder of the displays contained coherent motion (we recently found that incoherent motion enhances target disappearance, and we thus exploited this finding for present purposes; Wells, Leber, & Sparrow, 2009, OPAM). We predicted that if local target-mask interactions underlie MIB, disappearance should be greatest when the incoherent motion is closest to the target. Method: The mask was composed of three distinct, evenly spaced columns of moving dots, with fixation centered in the middle column. Observers were instructed to report the perceived disappearance of a peripheral target, which was presented in one of the outer columns. On 75% of the trials, local coherence was manipulated such that one of the three columns contained incoherent motion while the other two columns were coherent. For the remaining trials, all columns were coherent. Results/Conclusions: Observers reported greater disappearance on trials containing incoherent motion, replicating our previous results. Interestingly, this enhanced disappearance occurred regardless of which column contained the incoherence. Specifically, incoherence in the center column generated the greatest disappearance, followed by incoherence in the target and opposite columns; these latter two produced similar enhanced rates of disappearance compared to the all-coherent condition. These findings do not support a mechanism in which local target-mask competition mediates MIB. Rather, the properties of the mask responsible for the phenomenon seem insensitive to the target location and also appear to scale with eccentricity.