Post Robert B, Welch Robert B, Whitney David
Department of Psychology, University of California, Davis, CA 95616, USA.
Exp Brain Res. 2008 Dec;191(4):495-504. doi: 10.1007/s00221-008-1550-2. Epub 2008 Aug 27.
This research examined motor measures of the apparent egocentric location and perceptual measures of the apparent allocentric location of a target that was being seen to undergo induced motion (IM). In Experiments 1 and 3, subjects fixated a stationary dot (IM target) while a rectangular surround stimulus (inducing stimulus) oscillated horizontally. The inducing stimulus motion caused the IM target to appear to move in the opposite direction. In Experiment 1, two dots (flashed targets) were flashed above and below the IM target when the surround had reached its leftmost or rightmost displacement from the subject's midline. Subjects pointed open-loop at either the apparent egocentric location of the IM target or at the bottom of the two flashed targets. On separate trials, subjects made judgments of the Vernier alignment of the IM target with the flashed targets at the endpoints of the surround's oscillation. The pointing responses were displaced in the direction of the previously seen IM for the IM target and to a lesser degree for the bottom flashed target. However, the allocentric Vernier judgments demonstrated no perceptual displacement of the IM target relative to the flashed targets. Thus, IM results in a dissociation of egocentric location measures from allocentric location measures. In Experiment 2, pointing and Vernier measures were obtained with stationary horizontally displaced surrounds and there was no dissociation of egocentric location measures from allocentric location measures. These results indicate that the Roelofs effect did not produce the pattern of results in Experiment 1. In Experiment 3, pointing and Vernier measures were obtained when the surround was at the midpoint of an oscillation. In this case, egocentric pointing responses were displaced in the direction of surround motion (opposite IM) for the IM target and to a greater degree for the bottom flashed target. However, there was no apparent displacement of the IM target relative to the flashed targets in the allocentric Vernier judgments. Therefore, in Experiment 3 egocentric location measures were again dissociated from allocentric location measures. The results of this experiment also demonstrate that IM does not generate an allocentric displacement illusion analogous to the "flash-lag" effect.
本研究考察了一个被观察到正在经历诱导运动（IM）的目标的视自我中心位置的运动测量以及视他中心位置的感知测量。在实验1和实验3中，当一个矩形环绕刺激（诱导刺激）水平振荡时，受试者注视一个静止的点（IM目标）。诱导刺激的运动使IM目标看起来向相反方向移动。在实验1中，当环绕刺激从受试者中线达到其最左或最右位移时，在IM目标的上方和下方闪烁两个点（闪烁目标）。受试者开环指向IM目标的视自我中心位置或两个闪烁目标的底部。在单独的试验中，受试者在环绕刺激振荡的端点处对IM目标与闪烁目标的游标对齐进行判断。对于IM目标，指向反应在先前看到的IM方向上发生位移，对于底部闪烁目标，位移程度较小。然而，他中心游标判断表明IM目标相对于闪烁目标没有感知位移。因此，诱导运动导致了自我中心位置测量与他中心位置测量的分离。在实验2中，使用静止的水平位移环绕刺激获得指向和游标测量结果，自我中心位置测量与他中心位置测量没有分离。这些结果表明，罗洛夫斯效应并没有在实验1中产生结果模式。在实验3中，当环绕刺激处于振荡中点时获得指向和游标测量结果。在这种情况下，对于IM目标，自我中心指向反应在环绕运动方向（与诱导运动相反）上发生位移，对于底部闪烁目标，位移程度更大。然而，在他中心游标判断中，IM目标相对于闪烁目标没有明显位移。因此，在实验3中，自我中心位置测量再次与他中心位置测量分离。本实验的结果还表明，诱导运动不会产生类似于“闪光滞后”效应的他中心位移错觉。
