Human Tails: Ownership and Control of Extended Humanoid Avatars 


This paper explores body own­er­ship and con­trol of an “exten­ded” humanoid avatar that fea­tures a dis­tinct and flex­ible tail-like append­age pro­trud­ing from its coc­cyx. Thirty-two par­ti­cipants took part in a between-groups study to pup­pet­eer the avatar in an immers­ive CAVETM-like sys­tem. Par­ti­cipants’ body move­ment was tracked, and the avatar’s humanoid body syn­chron­ously reflec­ted this motion. How­ever, six­teen par­ti­cipants exper­i­enced the avatar’s tail mov­ing around ran­domly and asyn­chron­ous to their own move­ment, while the oth­er par­ti­cipants exper­i­enced a tail that they could, poten­tially, con­trol accur­ately and syn­chron­ously through hip move­ment. Par­ti­cipants in the syn­chron­ous con­di­tion exper­i­enced a high­er degree of body own­er­ship and agency, sug­gest­ing that visuo­mo­tor syn­chrony enhanced the prob­ab­il­ity of own­er­ship over the avatar body des­pite of its extra-human form. Par­ti­cipants exper­i­en­cing body own­er­ship were also more likely to be more anxious and attempt to avoid vir­tu­al threats to the tail and body. The high­er task per­form­ance of par­ti­cipants in the syn­chron­ous con­di­tion indic­ates that people are able to quickly learn how to remap nor­mal degrees of bod­ily free­dom in order to con­trol vir­tu­al bod­ies that dif­fer from the humanoid form. We dis­cuss the implic­a­tions and applic­a­tions of exten­ded humanoid avatars as a meth­od for explor­ing the plas­ti­city of the brain’s rep­res­ent­a­tion of the body and for ges­tur­al human-com­puter interfaces.


This pro­ject was sup­por­ted by the FP7 EU col­lab­or­at­ive pro­ject BEAMING (248620). Mel Slater was also sup­por­ted by the ERC Advanced Grant TRAVERSE.


  title={Human tails: ownership and control of extended humanoid avatars},
  author={Steptoe, William and Steed, Anthony and Slater, Mel},
  journal={Visualization and Computer Graphics, IEEE Transactions on},