Faculty of Design, Kyushu University, Japan.
Psychol Sci. 2012 Feb;23(2):126-32. doi: 10.1177/0956797611422236. Epub 2011 Dec 29.
After viewing a colored figure on a uniform gray background, an observer will see a negative afterimage after the colored figure disappears. This study shows that the shapes of afterimages vary systematically according to the shape of the adaptation stimuli, a phenomenon that could be caused only by cortical shape adaptation. In the experiments reported here, participants typically saw a hexagonal afterimage after viewing a circle and sometimes saw a circular afterimage after viewing a hexagon. When observers were adapted to rotating circles or hexagons, which produced the same circular retinal painting, they reliably reported that afterimages of circles appeared as hexagons, and vice versa. Furthermore, the fact that this effect also arose through interocular transfer confirms that a cortical process with binocular inputs must have contributed to it. This novel finding reveals that afterimage formation is determined mainly by a cortical process, not by retinal bleaching, and that rival mechanisms detect corners and curves of shapes in cortical processing.
在观察一个彩色图形在均匀灰色背景上之后，当彩色图形消失时观察者会看到负后像。本研究表明，后像的形状根据适应刺激的形状系统地变化，这种现象只能由皮层形状适应引起。在本报告的实验中，参与者在观看圆形后通常会看到六边形后像，有时在观看六边形后会看到圆形后像。当观察者适应于旋转的圆形或六边形，它们产生相同的圆形视网膜绘画时，他们可靠地报告说圆形的后像呈现为六边形，反之亦然。此外，通过双眼间转移产生这种效果的事实证实，具有双眼输入的皮层过程必须对此有贡献。这一新发现表明，后像形成主要由皮层过程决定，而不是由视网膜漂白决定，并且竞争机制在皮层处理中检测形状的角和曲线。
