Platkiewicz Jonathan, Hayward Vincent
Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche 7222, Institut des Systèmes Intelligents et de Robotique, Paris, France.
J Neurophysiol. 2014 Apr;111(7):1409-16. doi: 10.1152/jn.00557.2013. Epub 2014 Jan 8.
Two objects of similar visual aspects and of equal mass, but of different sizes, generally do not elicit the same percept of heaviness in humans. The larger object is consistently felt to be lighter than the smaller, an effect known as the "size-weight illusion." When asked to repeatedly lift the two objects, the grip forces were observed to adapt rapidly to the true object weight while the size-weight illusion persisted, a phenomenon interpreted as a dissociation between perception and action. We investigated whether the same phenomenon can be observed if the mass of an object is available to participants through inertial rather than gravitational cues and if the number and statistics of the stimuli is such that participants cannot remember each individual stimulus. We compared the responses of 10 participants in 2 experimental conditions, where they manipulated 33 objects having uncorrelated masses and sizes, supported by a frictionless, air-bearing slide that could be oriented vertically or horizontally. We also analyzed the participants' anticipatory motor behavior by measuring the grip force before motion onset. We found that the perceptual illusory effect was quantitatively the same in the two conditions and observed that both visual size and haptic mass had a negligible effect on the anticipatory gripping control of the participants in the gravitational and inertial conditions, despite the enormous differences in the mechanics of the two conditions and the large set of uncorrelated stimuli.
两个视觉外观相似、质量相等但大小不同的物体，在人类中通常不会引发相同的重量感知。较大的物体总是被感觉比小的物体轻，这种效应被称为“大小-重量错觉”。当要求反复举起这两个物体时，观察到握力会迅速适应物体的真实重量，而大小-重量错觉依然存在，这一现象被解释为感知与行动之间的分离。我们研究了如果物体的质量通过惯性而非重力线索提供给参与者，并且刺激的数量和统计情况使得参与者无法记住每个单独的刺激，是否能观察到相同的现象。我们比较了10名参与者在两种实验条件下的反应，在这两种条件下，他们操控33个质量和大小不相关的物体，这些物体由一个无摩擦的气浮滑块支撑，该滑块可以垂直或水平放置。我们还通过测量运动开始前的握力来分析参与者的预期运动行为。我们发现，在这两种条件下，感知错觉效应在数量上是相同的，并且观察到，尽管两种条件下的力学原理存在巨大差异以及有大量不相关的刺激，但视觉大小和触觉质量对重力和惯性条件下参与者的预期抓握控制的影响都可以忽略不计。
