Blom Tessel, Liang Qianchen, Hogendoorn Hinze
Melbourne School of Psychological Sciences, University of Melbourne, Melbourne, Australia.
Helmholtz Institute, Department of Experimental Psychology, Utrecht University, Utrecht, The Netherlands.
J Vis. 2019 Feb 1;19(2):3. doi: 10.1167/19.2.3.
Motion-induced position shifts constitute a broad class of visual illusions in which motion and position signals interact in the human visual pathway. In such illusions, the presence of visual motion distorts the perceived positions of objects in nearby space. Predictive mechanisms, which could contribute to compensating for processing delays due to neural transmission, have been given as an explanation. However, such mechanisms have struggled to explain why we do not usually perceive objects extrapolated beyond the end of their trajectory. Advocates of this interpretation have proposed a "correction-for-extrapolation" mechanism to explain this: When the object motion ends abruptly, this mechanism corrects the overextrapolation by shifting the perceived object location backwards to its actual location. However, such a mechanism has so far not been empirically demonstrated. Here, we use a novel version of the flash-grab illusion to demonstrate this mechanism. In the flash-grab effect, a target is flashed on a moving background that abruptly changes direction, leading to the mislocalization of the target. Here, we manipulate the angle of the direction change to dissociate the contributions of the background motion before and after the flash. Consistent with previous reports, we observe that perceptual mislocalization in the flash-grab illusion is mainly driven by motion after the flash. Importantly, however, we reveal a small but consistent mislocalization component in the direction opposite to the direction of the first motion sequence. This provides empirical support for the proposed correction-for-extrapolation mechanism, and therefore corroborates the interpretation that motion-induced position shifts might result from predictive interactions between motion and position signals.
运动诱发的位置偏移构成了一类广泛的视觉错觉，其中运动和位置信号在人类视觉通路中相互作用。在这类错觉中，视觉运动的存在会扭曲附近空间中物体的感知位置。有人提出预测机制可用于补偿神经传导导致的处理延迟，但这种机制难以解释为什么我们通常不会感知到物体超出其轨迹终点的外推情况。这种解释的支持者提出了一种“外推校正”机制来解释这一现象：当物体运动突然结束时，该机制通过将感知到的物体位置向后移动到其实际位置来校正过度外推。然而，到目前为止，这种机制尚未得到实证证明。在此，我们使用一种新型的闪光捕捉错觉来证明这种机制。在闪光捕捉效应中，一个目标在突然改变方向的移动背景上闪烁，导致目标的定位错误。在此，我们操纵方向改变的角度，以区分闪光前后背景运动的贡献。与之前的报告一致，我们观察到闪光捕捉错觉中的感知定位错误主要由闪光后的运动驱动。然而，重要的是，我们在与第一个运动序列方向相反的方向上发现了一个小但一致的定位错误成分。这为所提出的外推校正机制提供了实证支持，因此证实了运动诱发的位置偏移可能源于运动和位置信号之间的预测性相互作用这一解释。
