Pavani F, Boscagli I, Benvenuti F, Rabuffetti M, Farnè A
Dipartimento di Psicologia, Università degli Studi di Bologna, Italy.
Exp Brain Res. 1999 Jul;127(1):95-101. doi: 10.1007/s002210050777.
In the present study, we investigated the effects of the Titchener circles illusion in perception and action. In this illusion, two identical discs can be perceived as being different in size when one is surrounded by an annulus of smaller circles and the other is surrounded by an annulus of larger circles. This classic size-contrast illusion, known as Ebbinghaus or Titchener Circles Illusion, has a strong perceptual effect. By contrast, it has recently been demonstrated that when subjects are required to pick up one of the discs, their grip aperture during reaching is largely appropriate to the size of the target. This result has been considered as evidence of a clear dissociation between visual perception and visuomotor behaviour in the intact human brain. In this study, we suggest and investigate an alternative explanation for these results. We argue that, in a previous study, while perception was subjected to the simultaneous influence of the large and small circles displays, in the grasping task only the annulus of circles surrounding the target object was influential. We tested this hypothesis by requiring 18 subjects to perceptually estimate and grasp a disc centred in a single annulus of Titchener circles. The results showed that both the perceptual estimation and the hand shaping while grasping the disc were similarly influenced by the illusion. Moreover, the stronger the perceptual illusion, the greater the effect on the grip scaling. We discuss the results as evidence of an interaction between the functional pathways for perception and action in the intact human brain.
在本研究中，我们调查了Titchener圆错觉在感知和行动方面的影响。在这种错觉中，当一个圆盘被较小的圆圈组成的环包围，而另一个圆盘被较大的圆圈组成的环包围时，两个相同的圆盘会被感知为大小不同。这种经典的大小对比错觉，即艾宾浩斯或Titchener圆错觉，具有很强的感知效果。相比之下，最近有研究表明，当要求受试者拿起其中一个圆盘时，他们在伸手抓取过程中的抓握孔径在很大程度上与目标大小相匹配。这一结果被视为完整人类大脑中视觉感知与视觉运动行为明显分离的证据。在本研究中，我们提出并研究了对这些结果的另一种解释。我们认为，在之前的一项研究中，虽然感知受到大小圆圈展示的同时影响，但在抓握任务中，只有围绕目标物体的圆圈环具有影响力。我们通过要求18名受试者对视错觉中的圆盘进行感知估计并抓取，来检验这一假设。结果表明，在抓握圆盘时，感知估计和手部形状都同样受到错觉的影响。此外，感知错觉越强，对抓握缩放的影响就越大。我们将这些结果作为完整人类大脑中感知和行动功能通路之间存在相互作用的证据进行讨论。
