Rake-it-ball: Trying to measure tool-embodiment through a body-part compatibility task


Tool embodiment refers to the effects of tool-use on the coding of space and our body schema such that the tool becomes "an extension" of our physical effectors. One task that was thought to index this phenomenon was the body-part compatibility task because it provided an index of what is or is not being coded as a body part in the body schema. Previous employment of a body-part compatibility task has revealed a modification of the body schema when a tool was manipulated physically or virtually. The present study investigated the validity of the body-part compatibility task to measure tool-embodiment by assessing two types of interactions: 1) perception of the physical tool-interaction task, and 2) completion of math questions without any tool-interaction. Before and after the tool-interaction task, participant completed a body-part compatibility task in which they responded to targets presented on the image of a model holding a rake. Targets were presented on the foot, hand and rake. The first group made reaching movements to a target presented on an image of the actual tool interaction task while the control group completed math problems instead of any type of tool interaction. The results of the two groups were similar wherein the pattern of reaction times (RTs) indicated the emergence of tool-embodiment. The RTs to targets presented on the hand and the rake were found to be similar after completing a tool-irrelevant interaction task. These results indicate that the body-part compatibility task may not correctly assess tool-embodiment.

Acknowledgments: This research was supported by grants from SSHRC and NSERC.