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Ricardo Max, Yehoshua Tsal; Flanker Effects Reflect (Early) Suppression Delays Rather Than (Late) Response Competition. Journal of Vision 2017;17(10):1329. doi: 10.1167/17.10.1329.
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© ARVO (1962-2015); The Authors (2016-present)
When a target (two alternative identities) is flanked by incongruent distractors (bearing the alternative target identity), responses are typically slower compared to neutral flankers (Eriksen & Eriksen, 1974). A golden standard for investigating attentional selection, the flanker effect (slower responses for incongruent displays) has been traditionally interpreted as a late time-consuming competition between post-perceptual representations of both target identities that simultaneously activate both motor responses. This response compatibility effect has been exclusively attributed to the response system rather than to the perceptual or cognitive processing of the stimuli (Eriksen, 1995). If so, processing proceeds similarly for both display types during early stages, but is prolonged within incongruent displays during late post-perceptual stages. We tested this prediction in a series of experiments employing the mutations paradigm (Max & Tsal, 2015), by comparing between the processing timecourses of incongruent and neutral displays. Methods: (a) While the target remained constant until response, distractors mutated once, at a random time within 100 ms following stimulus onset. Three types of mutation trials — incongruent distractors mutated to neutral; vice versa; or neutral to neutral (control) — were intermixed with baseline trials (incongruent and neutral displays without mutations). Comparisons between different trial types within each mutation time, revealed the time-window during which (disruptive) distractor information was accumulated. (b) Incongruent and neutral displays masked at random times revealed until when critical target information was accumulated (after which masking became inconsequential). Results: Incongruent distractors were suppressed 42 ms later than neutral distractors (at 67 and 25 ms, respectively). Following distractor suppression, exclusive target processing persisted for additional 24 and 33 ms (respectively), followed by additional 355 and 356 ms until response (at 446 and 414 ms, respectively). Conclusions: The 32-ms-slower responses for incongruent displays (flanker effect) reflected the 42-ms delay necessary to suppress incongruent distractors (initial pre-selection stage), rather than a late post-perceptual response competition.
Meeting abstract presented at VSS 2017
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