van Heusden Elle, Harris Anthony M, Garrido Marta I, Hogendoorn Hinze
Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, Australia.
Helmholtz Institute, Department of Experimental Psychology, Utrecht University, Utrecht, the Netherlands.
J Vis. 2019 Jan 2;19(1):3. doi: 10.1167/19.1.3.
Neural processing of sensory input in the brain takes time, and for that reason our awareness of visual events lags behind their actual occurrence. One way the brain might compensate to minimize the impact of the resulting delays is through extrapolation. Extrapolation mechanisms have been argued to underlie perceptual illusions in which moving and static stimuli are mislocalised relative to one another (such as the flash-lag and related effects). However, where in the visual hierarchy such extrapolation processes take place remains unknown. Here, we address this question by identifying monocular and binocular contributions to the flash-grab illusion. In this illusion, a brief target is flashed on a moving background that reverses direction. As a result, the perceived position of the target is shifted in the direction of the reversal. We show that the illusion is attenuated, but not eliminated, when the motion reversal and the target are presented dichoptically to separate eyes. This reveals extrapolation mechanisms at both monocular and binocular processing stages contribute to the illusion. We interpret the results in a hierarchical predictive coding framework, and argue that prediction errors in this framework manifest directly as perceptual illusions.
大脑对感觉输入的神经处理需要时间，因此我们对视觉事件的感知滞后于它们的实际发生。大脑可能用来补偿以尽量减少由此产生的延迟影响的一种方式是通过外推法。外推机制被认为是一些感知错觉的基础，在这些错觉中，运动和静态刺激相对于彼此的定位出现错误（例如闪光滞后及相关效应）。然而，这种外推过程在视觉层级结构的哪个位置发生仍然未知。在这里，我们通过确定单眼和双眼对闪光捕捉错觉的影响来解决这个问题。在这种错觉中，一个短暂的目标在反向运动的背景上闪现。结果，目标的感知位置在反向的方向上发生偏移。我们发现，当运动反向和目标分别呈现给两只分开的眼睛时，这种错觉会减弱，但不会消除。这表明单眼和双眼处理阶段的外推机制都导致了这种错觉。我们在分层预测编码框架中解释这些结果，并认为该框架中的预测误差直接表现为感知错觉。
