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Joseph Schmidt, Gregory Zelinsky; Visual search guidance is best shortly after target preview offset. Journal of Vision 2009;9(8):1183. doi: 10.1167/9.8.1183.
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© ARVO (1962-2015); The Authors (2016-present)
At last year's VSS (Schmidt & Zelinsky, 2008) we reported that visual search guidance improves when a short delay is inserted between the target preview and the search display, a benefit that we attributed to consolidation of the target representation being time-locked to the preview offset. To further explore this hypothesis, we conducted a series of experiments in which a pictorial target preview was followed by a 5-item search display (all photorealistic objects). In one experiment we systematically manipulated ISI and found a guidance benefit for preview-search delays in the 300–600 msec range. In another experiment we replicated this effect with a short preview duration to show that benefits are linked to preview offset rather than better encoding. Lastly, we flashed at preview offset either a colored noise mask or a distractor item from the search display, and found that the target-related guidance benefit persisted despite the presence of this potentially disruptive visual information. Moreover, when a distractor item was flashed at preview offset, gaze was not guided to this item in the search display; indeed we found guidance away from this object in target-absent trials after an ISI, indicating an active suppression of the flashed distractor. This further suggests that preview-related guidance is more than simple obligatory visual priming, as the flashed distractor and not the target was viewed last. We interpret these data as evidence for a guidance process that begins to exert itself after attention is disengaged from the guiding stimulus (e.g., preview offset), with the process of elaborating a target template requiring ~300 msec and lasting until ~600 msec in this task. This elaborative process is highly selective to target features and relatively immune from interference related to brief visual interruptions, a necessary quality in a guidance system designed to work in the real world.
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