Guo Kun, Nevado Angel, Robertson Robert G, Pulgarin Maribel, Thiele Alexander, Young Malcolm P
Department of Psychology, University of Newcastle, Henry Wellcome Building for Neuroecology, Newcastle upon Tyne NE2 4HH, UK.
Vision Res. 2004;44(20):2349-58. doi: 10.1016/j.visres.2004.04.014.
Spatial and temporal regularities commonly exist in natural visual scenes. The knowledge of the probability structure of these regularities is likely to be informative for an efficient visual system. Here we explored how manipulating the spatio-temporal prior probability of stimuli affects human orientation perception. Stimulus sequences comprised four collinear bars (predictors) which appeared successively towards the foveal region, followed by a target bar with the same or different orientation. Subjects' orientation perception of the foveal target was biased towards the orientation of the predictors when presented in a highly ordered and predictable sequence. The discrimination thresholds were significantly elevated in proportion to increasing prior probabilities of the predictors. Breaking this sequence, by randomising presentation order or presentation duration, decreased the thresholds. These psychophysical observations are consistent with a Bayesian model, suggesting that a predictable spatio-temporal stimulus structure and an increased probability of collinear trials are associated with the increasing prior expectation of collinear events. Our results suggest that statistical spatio-temporal stimulus regularities are effectively integrated by human visual cortex over a range of spatial and temporal positions, thereby systematically affecting perception.
空间和时间规律通常存在于自然视觉场景中。了解这些规律的概率结构可能对高效的视觉系统具有指导意义。在此，我们探究了操纵刺激的时空先验概率如何影响人类的方向感知。刺激序列由四个共线条（预测物）组成，它们相继朝着中央凹区域出现，随后是一个具有相同或不同方向的目标条。当以高度有序且可预测的序列呈现时，受试者对中央凹目标的方向感知会偏向预测物的方向。辨别阈值随着预测物先验概率的增加而显著升高。通过随机化呈现顺序或呈现持续时间来打破这个序列，会降低阈值。这些心理物理学观察结果与贝叶斯模型一致，表明可预测的时空刺激结构以及共线试验概率的增加与共线事件的先验期望增加相关。我们的结果表明，人类视觉皮层在一系列空间和时间位置上有效地整合了统计时空刺激规律，从而系统地影响感知。
