Attentional selection by distractor suppression

Abstract

Selective attention was studied in displays containing singletons popping out for their odd form or color. The target was defined as the form-singleton, the distractor as the color-singleton. The task was to discriminate the length of a longer line inside the target. Target-distractor similarity was controlled using a threshold measurement as dependent variable in experiments in which distractor presence vs absence, bottom-up vs top-down selection (through knowledge of target features), and target-distractor distance were manipulated. The results in the bottom-up condition showed that length threshold was elevated when a distractor was present and that this elevation progressively increased as the number of distractors was increased from one to two. This set-size effect was not accounted by the hypothesis that selective attention intervenes only at the stage of decision before response. Selective attention produced a suppressive surround in which discriminability of neighboring objects was strongly reduced, and a larger surround in which discriminability was reduced by an approximately constant amount. Different results were found in the top-down condition in which target discriminability was unaffected by distractor presence and no effect of target-distractor distance was found. On the other hand, response times in both bottom-up and top-down conditions were slower the shorter the target-distractor distance was. On the basis of the experimental results, selective attention is a parallel process of spatial filtering at an intermediate processing level operating after objects have been segmented. This filtering stage explores high level interactions between objects taking control on combinatorial explosion by operating over only a limited spatial extent: it picks out a selected object and inhibits the neighboring objects; then, non-selected objects are suppressed across the overall image. When no feature-based selection is available in the current behavior, this filtering influences perception in decreasing discriminability of non-selected objects. When feature-based selection is available, spatial interactions are set before stimulus arrival, hence only the unmatching objects have their discriminability diminished.

Direct neurophysiological evidence for spatial suppression surrounding the focus of attention in vision

“…Prior behavioral and physiological studies of the spatial distribution of attention, however, have provided mixed results, either in favor of a simple spatial gradient (18)(19)(20)(21)(22), or consistent with an inhibitory zone (25)(26)(27)(28)(29)(30)(31)(42)(43)(44). The present study demonstrates unequivocally that attending to an object leads to a ring of inhibition.…”

Context-sensitive binding by the laminar circuits of V1 and V2: A unified model of perceptual grouping, attention, and orientation contrast

“…However, this possibility fails to account for the fact mentioned above that attention can be inhibitory, as well as facilitatory. In particular, there is psychophysical and neurophysiological evidence that attention has a facilitatory on-center and suppressive offsurround form (Downing, 1988;Caputo & Guerra, 1998;Mounts, 2000;Smith, Singh, & Greenlee, 2000;Vanduffel, Tootell, & Orban, 2000). Moreover, there is evidence that corticocortical feedback axons act on both non-NMDA and NMDA channels (Cauller & Connors, 1994).…”

From reorienting of attention to biased competition: Evidence from hemifield effects

“…That this is the case has been known for quite some time (Pan & Eriksen, 1993;Sereno & Kosslyn, 1991), but not until recently has the link with biased competition been made explicit (Bahcall & Kowler, 1999;Caputo & Guerra, 1998 When a distractor was presented simultaneously with or directly following a target, it produced more interference when it was presented in the same visual hemifield as the target than when it was presented in the opposite visual field. This result is interpreted in terms of biased competition; there is more competition between stimuli when they are presented in the same visual field, rather than in opposite visual fields.…”