Greenwood J, Cavanagh P, 2011, "Transient target signals reduce crowding, transient flanker signals do not" Perception 40 ECVP Abstract Supplement, page 34
Transient target signals reduce crowding, transient flanker signals do not
J Greenwood, P Cavanagh
Crowding is the breakdown in object recognition that occurs in cluttered visual scenes. Given the predominant two-stage model of crowding, where object features are detected veridically prior to being pooled, can we restore access to the veridical features and abolish crowding? We suggest that transient visual signals can achieve this. Observers (n=4) judged the orientation of a target Gabor, flanked by 4 Gabors (2 deg centre-to-centre separation) at 10 deg. eccentricity. Midway through each 400 ms trial, stimulus elements could 'blink' off for 10–80 ms before returning. These 'blinks' were applied either to the whole array, the target only, or the flankers only. In the whole-array and flankers-only conditions, orientation thresholds were 3–6 times higher than uncrowded thresholds. However, when the target alone blinked, thresholds were restored to near-uncrowded levels. The strong crowding in the flankers-only condition demonstrates that target-flanker similarity (eg in temporal frequency) does not mediate this effect. Nor does position cueing suffice, as flashing a ring around the target gave little benefit. Rather, varying the blink duration suggests it is the separable onset of the target that matters. We propose that onset transients allow the correct features to be 'tagged' to their correct locations, thereby avoiding crowding.
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