Center for Cognitive Neuroscience & Duke Institute for Brain Sciences, Duke University, USA.
Department of Neuroscience & Visual Arts Department, Bowdoin College, USA.
Vision Res. 2021 Feb;179:42-52. doi: 10.1016/j.visres.2020.10.006. Epub 2020 Dec 4.
Individuals are adept at estimating average properties of group visual stimuli, even following brief presentations. In estimating the directional heading of walking human figures, judgments are biased in a peculiar manner: groups facing intermediate directions are perceived to be more leftward- or rightward-facing than actual averages. This effect was previously explained as a repulsive bias away from a central category boundary; groups along this boundary (directly facing the observer) are estimated with lower variability and with relatively greater accuracy. Here we show that: (i) the original effect replicates and is constant over time in a novel estimation task with persistent directional states; and, (ii) novel patterns of response variability and durations align with the entire range of overestimation. A simple model of additive errors proportional to viewer uncertainty matches the observed bias magnitudes. We furthermore show that the bias generalizes beyond approaching walkers with the use of rearward-facing walkers presented at a nonparallel angle. Overall, the recurring relation between bias and uncertainty is also consistent with top-down and post-perceptual causes of misestimation.
个体擅长估计群体视觉刺激的平均属性，即使在短暂呈现后也是如此。在估计行走人物的方向朝向时，判断会以一种奇特的方式产生偏差：与实际平均值相比，面对中间方向的群体被感知为更向左或更向右。这种效果以前被解释为一种从中心类别边界排斥的偏见；沿着这条边界（直接面对观察者）的群体估计具有较低的可变性和相对较大的准确性。在这里，我们表明：（i）在具有持续方向状态的新的估计任务中，原始效果复制并且随时间保持不变；并且，（ii）与整个高估范围一致的新的响应可变性和持续时间模式。与观察者不确定性成比例的附加误差的简单模型匹配观察到的偏差幅度。此外，我们还表明，该偏差不仅适用于使用以非平行角度呈现的向后行走者接近行走者。总体而言，偏差和不确定性之间的反复关系也与误估计的自上而下和后感知原因一致。
