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Andrew Leber, Rachael Gwinn, Ryan O'Toole; Simultaneous enhancement and suppression of distinct spatial locations. Journal of Vision 2013;13(9):474. doi: 10.1167/13.9.474.
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© ARVO (1962-2015); The Authors (2016-present)
Since von Helmholtz’s early studies of covert attention, it has been known that individuals can flexibly and voluntarily enhance the processing of stimuli at cued spatial locations. More recently, researchers have also characterized a complementary capacity to suppress cued locations. What remains unknown is how these functions of enhancement and suppression interact and whether or not they work independently. Here, we specifically questioned whether the two functions could be implemented simultaneously. Observers searched displays in which one location contained a target while another contained a salient, irrelevant distractor. Prior to the display onset, long and short arrow cues were presented; the former predicted the target with 70% validity and the latter predicted the distractor with 70% validity. Results showed a moderate target-validity effect but no distractor-validity effect. Upon considering the high-level demands on observers to process multiple cues, our next experiment circumvented this roadblock using via incidental learning. Now only one arrow cue was presented, predicting the target with 70% validity; also, unbeknownst to observers, this same cue predicted the distractor with 70% validity. Results now showed a robust target validity effect, confirming that the cues were attended and used. Critically, a learning effect emerged over time, in which interference from the salient distractor became significantly reduced. These results demonstrate that with a carefully devised experimental procedure, individuals do indeed simultaneously enhance and suppress multiple noncontiguous locations in the visual field. However, further analysis revealed a striking caveat: simultaneous enhancement and suppression only occurred when the target and distractor were presented in opposite visual hemifields, presumably relating to the hemispheric independence of attentional resources (Alvarez & Cavanagh, 2005). We thus conclude that the functions of enhancement and suppression can be used flexibly; however, they compete for common resources and are thus not fully separable in nature.
Meeting abstract presented at VSS 2013
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