Sayim Bilge, Greenwood John A, Cavanagh Patrick
Laboratory of Experimental Psychology, University of Leuven, Leuven, Belgium Université Paris Descartes, Sorbonne Paris Cité, Paris, France CNRS UMR 8158, Paris, France.
Université Paris Descartes, Sorbonne Paris Cité, Paris, France CNRS UMR 8158, Paris, France Experimental Psychology, University College London, London, UK.
J Vis. 2014 Oct 7;14(6):4. doi: 10.1167/14.6.4.
Crowding is the limitation of peripheral vision by clutter. Objects that are easily identified when presented in isolation are hard to identify when presented flanked by similar close-by objects. It is often assumed that the signal of a crowded target is irretrievably lost because it is combined with the signals of the flankers. Here, we asked whether a target signal can be enhanced (or retrieved) by items presented far outside the crowding region. We investigated whether remote items matching a peripheral, crowded target enhanced discrimination compared to remote items not matching the target. In Experiment 1, we presented the remote item at different locations in the visual field and found that, when presented in the fovea, a matching remote item improved target discrimination compared to a nonmatching remote item. In Experiment 2, we varied stimulus onset asynchronies between target and remote items and found a strong effect when the remote item was presented simultaneously with the target. The effect diminished (or was absent) with increasing temporal separation. In Experiment 3, we asked whether semantic knowledge of a target was sufficient to improve target discrimination and found that this was not the case. We conclude that crowded target signals are not irretrievably lost. Rather, their accurate recognition is facilitated in the presence of remote items that match the target. We suggest that long-range grouping mechanisms underlie this "uncrowding" effect.
拥挤现象是指周边视觉因视觉干扰而受到限制。单独呈现时易于识别的物体，在其周围有类似的近距离物体时则难以识别。人们通常认为，拥挤目标的信号会因与侧翼物体的信号合并而无可挽回地丢失。在此，我们探讨了目标信号是否能被呈现于拥挤区域之外远处的物体增强（或恢复）。我们研究了与不匹配目标的远处物体相比，匹配周边拥挤目标的远处物体是否能提高辨别能力。在实验1中，我们将远处物体呈现于视野中的不同位置，发现当呈现于中央凹时，与不匹配的远处物体相比，匹配的远处物体能改善目标辨别。在实验2中，我们改变了目标与远处物体之间的刺激起始异步性，发现当远处物体与目标同时呈现时效果显著。随着时间间隔增加，效果减弱（或消失）。在实验3中，我们探讨目标的语义知识是否足以改善目标辨别，发现并非如此。我们得出结论，拥挤的目标信号并非无可挽回地丢失。相反，在存在与目标匹配的远处物体时，它们的准确识别会得到促进。我们认为，这种“解拥挤”效应的基础是远距离分组机制。
