Corbett Jennifer E, Enns James T, Handy Todd C
Center for Mind and Brain, The University of California, Davis, CA 95618, USA.
Brain Res. 2009 Oct 6;1292:82-92. doi: 10.1016/j.brainres.2009.07.038. Epub 2009 Jul 23.
Visual orientation cues largely determine our perceptions of "vertical," as illustrated in the Rod and Frame Illusion (RFI): an upright rod appears slanted in the opposite direction of a surrounding tilted frame. We used event-related potentials (ERPs) to examine the cortical time course of the frame's illusory influence on the perceived orientation of the rod. ERPs to an orientation discrimination task revealed: 1) the amplitudes of the P1 and N1 (indices of early visual processing) were not affected by frame tilt, but the amplitude of the P3 (an index of later processing) was, and 2) increasing the perceptual difficulty of the rod tilt judgment did not affect the P1 or N1, but increased response time and attenuated P3 amplitude. Results suggest that global orientation context effects are manifest during later, post-perceptual stages of information processing.
视觉定向线索在很大程度上决定了我们对“垂直”的感知，如杆框错觉（RFI）所示：一根直立的杆在周围倾斜框架的相反方向看起来是倾斜的。我们使用事件相关电位（ERP）来研究框架对杆的感知方向的错觉影响的皮层时间进程。对定向辨别任务的ERP显示：1）P1和N1（早期视觉处理指标）的振幅不受框架倾斜的影响，但P3（后期处理指标）的振幅受影响；2）增加杆倾斜判断的感知难度不会影响P1或N1，但会增加反应时间并减弱P3振幅。结果表明，全局定向背景效应在信息处理的后期、感知后阶段表现出来。
