The toolish hand illusion: embodiment of a tool based on similarity with the hand

Lucilla Cardinali,Russell Yanofsky,Alice C Roy,Frédérique De Vignemont,Alessandro Farnè,Alessandro Zanini,Jody C Culham

doi:10.1038/s41598-021-81706-6

Abstract

A tool can function as a body part yet not feel like one: Putting down a fork after dinner does not feel like losing a hand. However, studies show fake body-parts are embodied and experienced as parts of oneself. Typically, embodiment illusions have only been reported when the fake body-part visually resembles the real one. Here we reveal that participants can experience an illusion that a mechanical grabber, which looks scarcely like a hand, is part of their body. We found changes in three signatures of embodiment: the real hand’s perceived location, the feeling that the grabber belonged to the body, and autonomic responses to visible threats to the grabber. These findings show that artificial objects can become embodied even though they bear little visual resemblance to the hand.

Highlights

A tool can function as a body part yet not feel like one: Putting down a fork after dinner does not feel like losing a hand
Though we manipulate dozens of tools during the day, could we feel that a fork, a toothbrush or a screwdriver belong to us in the same way our hands do? Here we investigate whether a tool can be processed as a body part at the spatial level, and at the physiological level, and at the phenomenological level
While these previous studies showed that tool use affects sensorimotor and spatial representations, they did not address whether it affects body ownership, that is, whether using a tool makes it feel more like a part of one’s own body

Summary

Introduction

A tool can function as a body part yet not feel like one: Putting down a fork after dinner does not feel like losing a hand. We found changes in three signatures of embodiment: the real hand’s perceived location, the feeling that the grabber belonged to the body, and autonomic responses to visible threats to the grabber These findings show that artificial objects can become embodied even though they bear little visual resemblance to the hand. Tool use modifies the visual properties of peripersonal space, recoding far space as n earer[12,16,17], and enhancing the defensive monitoring of such s pace[18] While these previous studies showed that tool use affects sensorimotor and spatial representations, they did not address whether it affects body ownership, that is, whether using a tool makes it feel more like a part of one’s own body.

Methods

Results

Conclusion