AUTHOR=Ruijia Yang , Sakura Hirokazu , Gunji Yukio-Pegio 

TITLE=Feeling of hand deformation as a monkey's hand: an experiment on a visual body with discomfort and its algebraic analysis

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 17 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2023.975597

DOI=10.3389/fnins.2023.975597

ISSN=1662-453X

ABSTRACT=While there are many researches on which sense of body ownership can be transited to a virtual body, there is little experimental study of which how subjects feel about a deformed subject’s own body since a real body cannot be deformed. We here propose such an experimental setup in which a twisted hand is diagonally viewed from behind, which is called “monkey’s hand”. Although a subject cannot see a thumb hidden behind his/her arm, he/she feels that the monkey’s hand has originally no thumb and recognizes that four fingers constitute a whole hand. We show that there is adrift on the touched point and the indication in a term of proprioception under the monkey’s hand condition, and that body deformation is felt with a sense of ownership. Indeed, we analyzed post-experimental questionnaires with respect to a specific algebraic structure called a lattice, and show that a subject felt that the thumb which cannot be seen is recognized as the ambiguous state of existing and non-existing.