The perception of real and illusory weight differences with grasping tools

Abstract

Humans routinely use tools to extend their repertoire of skilled behavior, using their action capabilities to enhance reach, dexterity, or strength. Little is known, however, about how using a tool affects our experience of object properties, such as heaviness. To better understand how using a tool to manipulate our environment affects perception, participants (n=44) lifted and reported the felt heaviness of objects which varied independently in size and mass. In a blocked repeated-measures design, they lifted with their anatomical hands and with a grasping tool. Contrary to our hypotheses, which was based on earlier work with prosthetic hands (Buckingham et al., 2018), participants experienced real and illusory weight differences just as robustly with a grasping tool as they did with their anatomical hands. These findings add to the growing body of work examining perception tool use and suggest that grasping tools may be incorporated differently into the representation of the body in action than prosthetic hands.