When hands are used to communicate they are less susceptible to illusion than when they are used to estimate

When we use our hands to estimate the size of sticks in the Müller-Lyer illusion, we are highly susceptible to the illusion. But when we prepare to act on sticks under the same conditions, we are significantly less susceptible to the illusion. Here we ask whether our hands are susceptible to illusion when used, not to act on objects, but to describe them in spontaneous co-speech gestures or in conventional sign languages of the Deaf. Thirty-two English-speakers and 13 ASL-signers used their hands to act on, estimate, and describe sticks eliciting the Müller-Lyer illusion. For both gesture and sign, the magnitude of illusion for description was smaller than the magnitude of illusion for estimation, and not different from the magnitude of illusion for action. The mechanisms responsible for producing these non-codified gestures and codified signs thus appear to operate, not on percepts involved in estimation, but are rather derived from the way we act on objects.

当我们运用双手去估测穆勒-莱尔错觉中的木棍尺寸时，我们极易受其错觉影响。然而，在相同条件下准备对木棍进行操作时，我们对其错觉的敏感性显著降低。本研究旨在探讨，当双手并非用于操作物体，而是用于在随说话时的自发伴随手势或手语（尤其是聋人的传统手语）中描述物体时，双手是否仍会受错觉影响。在本研究中，32名英语母语者和13名美国手语使用者（ASL）使用双手对产生穆勒-莱尔错觉的木棍进行操作、估测和描述。对于手势和手语而言，描述过程中的错觉强度低于估测过程中的错觉强度，且与操作过程中的错觉强度无显著差异。因此，产生这些非编码手势和编码手语的机制似乎并非源自于估测过程中所涉及的感知，而是源自于我们对物体的操作方式。