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Stephanie Goodhew, Elizabeth Shen, Mark Edwards; Selective spatial enhancement: Attentional spotlight sizes impacts spatial but not temporal perception. Journal of Vision 2015;15(12):1239. doi: 10.1167/15.12.1239.
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© 2017 Association for Research in Vision and Ophthalmology.
Visual spatial attention is a core function that prevents limited sensory resources from being overwhelmed by input. A prevailing assumption in the field has been the notion of ‘universal enhancement’ – that attention confers an advantage on all aspects of processing, and the greater the density of attentional resources applied to a stimulus (a ‘focal’ attentional spotlight), the greater the magnitude of the enhancement relative to when these resources are spread more thinly (a ‘diffuse’ attentional spotlight). Recent results, however, challenge this notion. Here we instead propose a novel theory of visual attention, which draws on the established physiological properties of the two major types of visual cells: magnocellular (M-cell) and parvocellular (P-cell) neurons. P cells have greater spatial but poorer temporal acuity whereas M cells have greater temporal but poorer spatial acuity. We reasoned that focussing attention into a small region should draw preferentially upon P-cells, given their smaller receptive field sizes, whereas spreading attentional resources more diffusely over a larger region should call preferentially upon M-cells with their larger receptive fields. This predicts that there should be a qualitative trade-off in spatial and temporal acuity as a function of attentional spotlight size, such that a focal spotlight enhances spatial resolution but impairs temporal resolution, whereas a diffuse spotlight impairs spatial resolution while enhancing temporal resolution. We call this novel theory the ‘spatiotemporal trade-off account’ of attention. We tested this by manipulating observers’ attentional spotlights to be either focal or diffuse, and then measuring their spatial and temporal acuity with spatial and temporal gap detection tasks. We found that while spatial acuity benefited from focal relative to a diffuse spotlight, attentional spotlight size had no impact on temporal acuity. These results do not confirm the spatiotemporal trade-off account, but they do directly challenge the notion of universal enhancement.
Meeting abstract presented at VSS 2015
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