Abstract
Visual search efficiency depends on both prioritization of relevant and suppression of irrelevant information. Context homogeneity has been identified as one factor that determines search efficiency. It has been argued that pre-attentive grouping may account for accelerated search because it allowed for processing of larger perceptual units. In a series of studies we investigated how grouping affects processing of targets and suppression of distractors. We used a spatial cueing task in which cues and targets were presented in contexts of varying homogeneity. When targets were presented at cued locations (valid trials), performance was best throughout all ISIs used. At short ISIs, when targets were presented at non-cued locations, performance was better when presented within the same context (invalid-inside trials) than when presented within a different context (invalid-outside trials). This context advantage was only observed when contexts were homogeneous, suggesting that sufficiently homogenous contexts were processed as one perceptual unit. In a follow-up study we investigated whether grouping does not only enhance prioritization of relevant, but also suppression of irrelevant information. Prioritization of targets and concurrent suppression of salient distractors was disentangled by using subcomponents of the attention-indicating N2pc in the ERP. The target-elicited NT component showed faster and more pronounced attention allocation for targets in homogeneous than in heterogeneous contexts. The distractor-elicited PD showed delayed distractor suppression in heterogeneous contexts and attentional capture by the distractor in heterogeneous, but not in homogeneous contexts. In sum, the present results show that pre-attentive grouping facilitates target processing and distractor suppression and suggest that goal-oriented processing is less vulnerable to interferences from potentially distracting low-level features in homogeneous contexts.
Meeting abstract presented at VSS 2014