Eye movements reveal distinct encoding patterns for number and cumulative surface area in random dot arrays.
Eye movements reveal distinct encoding patterns for number and cumulative surface area in random dot arrays.
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DOI：
10.1167/15.15.5
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发表时间：
2015-11
影响因子：
1.8
通讯作者：
Darko Odic;Justin Halberda
中科院分区：
文献类型：
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作者：
Darko Odic;Justin Halberda
人类可以通过近似数字系统（ANS）使用视觉证据快速直观地表示场景中物体的数量。但是支持视觉数字编码的计算——从视网膜输入到ANS表示的转换——仍然存在争议。已经提出了两种类型的数字编码理论：一种认为数字是通过专门的枚举计算编码的，另一种认为视觉数字是从非数字特定的视觉特征（如表面积、密度、凸壳等）中推断出来的。在这里，我们试图通过对参与者进行数字和累积区域任务测试，同时跟踪他们的眼球运动，来判断这两种理论之间的关系。我们假设，如果近似数和表面积依赖于不同的编码计算，那么即使视觉刺激相同，这两个任务的跳进特征也应该是不同的。与这一假设相一致，我们发现区分数字和累积区域会调节参与者看的地方（即，参与者在数字任务中花更多的时间看更多的集合，在累积区域任务中花更多的时间看更大的集合），以及参与者看的方式（即，累积区域编码显示出更少、更长的扫视，而数字编码显示出许多短扫视和目标之间的许多切换）。我们进一步确定了几个与任务难度和两个维度的正确与错误试验相关的跳眼特征。这些结果表明，不同的编码算法的数字和累积面积提取，从而不同的表示这些维度。
Humans can quickly and intuitively represent the number of objects in a scene using visual evidence through the Approximate Number System (ANS). But the computations that support the encoding of visual number-the transformation from the retinal input into ANS representations-remain controversial. Two types of number encoding theories have been proposed: those arguing that number is encoded through a dedicated, enumeration computation, and those arguing that visual number is inferred from nonnumber specific visual features, such as surface area, density, convex hull, etc. Here, we attempt to adjudicate between these two theories by testing participants on both a number and a cumulative area task while also tracking their eye-movements. We hypothesize that if approximate number and surface area depend on distinct encoding computations, saccadic signatures should be distinct for the two tasks, even if the visual stimuli are identical. Consistent with this hypothesis, we find that discriminating number versus cumulative area modulates both where participants look (i.e., participants spend more time looking at the more numerous set in the number task and the larger set in the cumulative area task), and how participants look (i.e., cumulative area encoding shows fewer, longer saccades, while number encoding shows many short saccades and many switches between targets). We further identify several saccadic signatures that are associated with task difficulty and correct versus incorrect trials for both dimensions. These results suggest distinct encoding algorithms for number and cumulative area extraction, and thereby distinct representations of these dimensions.