Perceived hand size and perceived hand weight

The dimensions of objects and our body parts influence our perception of the weight of objects in our surroundings. It has been recently described a dramatic underestimation of the perceived weight of the hand. However, little is known on how perceived size informs the perceived weight of our own body parts. Here we investigated the effects of embodying an enlarged and a shrunken hand on perceived hand weight. We manipulated hand size using a visual-tactile illusion with magnifying and minifying mirrors. We then measured perceived hand weight using a psychophysical matching task in which participants estimate if a weight hanged on their wrist feels heavier or lighter than the experienced weight of their hand. Our results indicated that participants tended to underestimate the weight of their hand more when embodying a smaller hand, and less so when embodying a larger hand. That is, the perceived size of the hand plays a role in shaping its perceived weight. Importantly, our results revealed that the perception of the weight of body parts is processed differently from the perception of object weight, demonstrating resistance to the size-weight illusion. We suggest a model based on constant density to elucidate the influence of hand size in determining hand weight.