Body-related components of action can be spatially coded along the size dimension.

This work aimed to examine whether the spatial representations of actions depend on the spatial features of the body components involved in those actions. I proposed that this is possible, but only when the responses cannot be spatially coded based on the spatial features of the actions' goal. I presented participants with large and small objects and instructed them to respond with either their palm-hand or index-digit based on the colour of the objects. Palm-hand or index-digit responses represented large and small responses, respectively, considering the size of the effector part used. The collected data confirmed this hypothesis. I found a size-based Simon effect, indicating that participants code the size of their responses based on the relative size of the body part used for responding (i.e., palm-hand vs. index-digit). This finding therefore suggests that the size-based Simon effect could serve as a valuable tool for implicitly assessing the metrics of body representation. (PsycInfo Database Record (c) 2025 APA, all rights reserved).