Physical load reduces synchrony effects on agency and ownership in the virtual hand illusion

Social exclusion in a virtual Cyberball game reduces the virtual hand illusion

Sense of ownership and agency are two important aspects of the minimal self, but how self-perception is affected by social conditions remains unclear. Here, we studied how social inclusion or exclusion of participants in the course of a virtual Cyberball game would affect explicit judgments and implicit measures of ownership and agency (proprioceptive drift, skin conductance responses, and intentional binding, respectively) in a virtual hand illusion paradigm, in which a virtual hand moved in or out of sync with the participants' own hand. Results show that synchrony affected all four measures. More importantly, this effect interacted with social inclusion/exclusion in the Cyberball game for both ownership and agency measure, showing that social exclusion reduces perceived agency and ownership.

Vicarious ostracism reduces observers' sense of agency

Previous findings revealed that social ostracism reduces people's implicit sense of agency. Based on theoretical claims that observed behavior of others may be cognitively represented similarly to one's own behavior, we conducted two experiments to test whether people's own sense of agency can also be impaired by observed social exclusion of others. In Experiment 1, participants recalled episodes referring to vicarious ostracism or inclusion before completing a temporal interval estimation task to assess intentional binding effects (an established implicit measure of the sense of agency). In Experiment 2, participants immersed into a newly designed virtual Cyberball game, in which they witnessed a vicarious ostracism or inclusion scenario, before completing a Libet-style temporal estimation task and an agency questionnaire (an explicit measure of the sense of agency). The findings show, for the first time, that vicarious ostracism reduces both implicit and explicit measures of agency in observers.

Evaluating Virtual Hand Illusion through Realistic Appearance and Tactile Feedback

We conducted a virtual reality study to explore virtual hand illusion through three levels of appearance (Appearance dimension: realistic vs. pixelated vs. toon hand appearances) and two levels of tactile feedback (Tactile dimension: no tactile vs. tactile feedback). We instructed our participants to complete a virtual assembly task in this study. Immediately afterward, we asked them to provide self-reported ratings on a survey that captured presence and five embodiment dimensions (hand ownership, touch sensation, agency and motor control, external appearance, and response to external stimuli). The results of our study indicate that (1) tactile feedback generated a stronger sense of presence, touch sensation, and response to external stimuli; (2) the pixelated hand appearance provided the least hand ownership and external appearance; and (3) in the presence of the pixelated hand, prior virtual reality experience of participants impacted their agency and motor control and their response to external stimuli ratings. This paper discusses our findings and provides design considerations for virtual reality applications with respect to the realistic appearance of virtual hands and tactile feedback.