Whole report uncovers correctly identified but incorrectly placed target information under visual crowding.
Whole report uncovers correctly identified but incorrectly placed target information under visual crowding.
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DOI：
10.1167/12.7.5
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发表时间：
2012-07
影响因子：
1.8
通讯作者：
Jun-Yun Zhang;Gong-Liang Zhang;Lei Liu;Cong Yu
中科院分区：
文献类型：
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作者：
Jun-Yun Zhang;Gong-Liang Zhang;Lei Liu;Cong Yu
多字母识别研究经常发现正确识别的字母被报告在错误的位置。然而，位置不确定性如何影响周边视觉中的拥挤现象尚不完全清楚。观察到侧卫被报告为中心目标不能作为位置误解的明确证据，因为观察者可能在未能识别中心目标时偏向于报告更可识别的侧卫。此外，在拥挤情况下，能否在侧翼位置感知到正确识别的中心目标，从未有过报道。对这种可能性的实证研究是证明拥挤中字母级别位置不确定性的关键，因为最难以识别的中心目标的位置误差不能归因于反应偏差。我们要求视力正常的观察者报告三联图的中心目标（部分报告）或全部三个字符（完整报告）。结果表明，对于放射状排列的三联图，在整个报告中，无论报告位置如何，报告中心目标的比率都显著高于部分报告率，而额外的目标报告大多出现在侧翼位置。误差分析表明，目标-侧卫位置交换和错位（目标和一个侧卫的横向移动）是目标错位的基础。因此，我们的结果确定了目标错位是拥挤误差的来源，并确定了字母水平位置不确定性在拥挤中的作用。
Multiletter identification studies often find correctly identified letters being reported in wrong positions. However, how position uncertainty impacts crowding in peripheral vision is not fully understood. The observation of a flanker being reported as the central target cannot be taken as unequivocal evidence for position misperception because the observers could be biased to report a more identifiable flanker when failing to identify the central target. In addition, it has never been reported whether a correctly identified central target can be perceived at a flanker position under crowding. Empirical investigation into this possibility holds the key to demonstrating letter-level position uncertainty in crowding, because the position errors of the least identifiable central target cannot be attributed to response bias. We asked normally-sighted observers to report either the central target of a trigram (partial report) or all three characters (whole report). The results showed that, for radially arranged trigrams, the rate of reporting the central target regardless of the reported position in the whole report was significantly higher than the partial report rate, and the extra target reports mostly ended up in flanker positions. Error analysis indicated that target-flanker position swapping and misalignment (lateral shift of the target and one flanker) underlay this target misplacement. Our results thus establish target misplacement as a source of crowding errors and ascertain the role of letter-level position uncertainty in crowding.