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Carmel Mevorach, Lilach Shalev, Glyn Humphreys; Left parietal patients have impaired salience suppression but only when there is response conflict. Journal of Vision 2012;12(9):128. doi: https://doi.org/10.1167/12.9.128.
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Recently it has been argued that the left posterior parietal cortex (PPC) is particularly important when low-salience targets need to be selected while high-salience distractors need to be ignored (salience-based selection). In particular, in the context of unilateral damage to the parietal cortex it has been shown that left parietal patients are impaired when responding to both local and global aspects of a compound letter stimulus as long as the target level is low in salience and the distractor level has high salience (Mevorach et al., 2006, Neuropsychologia). However, it is not clear whether this is a consequence of competition for perceptual representation or for response between target and distractor. In the present study we compared performance of left parietal patients and controls in a salience-based selection task which enabled us to separate competition for response from competition for perceptual representation. Superimposed faces and scenes where used in which either the face or the scene was more salient than the other. In different blocks of trials participants identified the face (ignoring the scene) or the scene (ignoring the face). Faces and scenes were either assigned to competing responses (Exp. 1 - response conflict) or were individually named (Exp. 2 - no response conflict). Interestingly, our left parietal patients were particularly impaired in responding to the less salient target under conditions of response conflict (Exp. 1) while their performance was comparable to that of controls when response competition was eliminated (Exp. 2). The results corroborate previous findings indicating the left PPC is implicated in the suppression of salient irrelevant information. Moreover, our findings suggest that the left PPC is particularly important when irrelevant, salient stimuli elicit a competing response. Thus, it appears that this region is important in an attention and action circuit that prevents us from producing inappropriate actions to salient distractors.
Meeting abstract presented at VSS 2012
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