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Orna Rosenthal, Martin Davies, Anne Aimola Davies, Glyn Humphreys; The role of spatial and non-spatial attention in MIB. Journal of Vision 2012;12(9):1330. doi: https://doi.org/10.1167/12.9.1330.
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Motion-induced-blindness (MIB) is an illusory phenomenon where one or more local salient targets surrounded by a moving flow field repeatedly undergo spontaneous disappearances for a short period. There is accumulated evidence indicating that frequency and duration of target disappearance increase when the targets are attended and salient. It has been suggested that the role of attention is to increase competition for selection between the relevant target and the irrelevant distractors (the moving flow field). However it is not clear (1) whether attention is a necessary or only a modulatory factor in MIB, and (2) what form of attention is important – spatial attention or attention to local (target) vs. global (distractor) context. We investigated these questions by studying MIB in a population of brain lesioned patients (N=20), who varied in type and severity of impaired attention. Reflexive spatial attention was assessed by measuring detection of briefly-presented stimuli in the left, right or both hemi-fields. Impairment in context-based attention was assessed with a Navon-like global vs. local letter-identification task. Using standard MIB stimulus and task settings, we measured the frequency of reporting illusory disappearance of local targets. Only patients who showed good detection of real disappearances in at least one hemi-field were included. All patients who showed severe spatial extinction (i.e. a failure to detect briefly-presented stimuli in the affected hemi-field when simultaneously presented with an ipsilesional stimulus) reported few illusory disappearances. For the remaining patients, the frequency of reporting illusory disappearances in the MIB task correlated significantly and positively with the degree of interference from an incongruent salient distractor on target letter detection in the Navon-like task. These findings suggest that (1) [broad] spatial attention is necessary for eliciting MIB, and (2) MIB depends on competition for attentional resources between relevant and irrelevant (but salient) contexts of the scene.
Meeting abstract presented at VSS 2012
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