The imaginary cat ears illusion: an analysis of ownership for an avatar’s cat ears via visual–auditory–haptic multimodal feedback in virtual reality

This is the authors' abstract. We don't add key points for this paper.

Introduction Avatars do not merely function as doubles that reproduce one's physical body; they can also extend or transform one's body representation and self-perception. On social VR platforms, semi-humanoid avatars augmented with non-human body parts such as tails, wings, or animal ears are widely used, and users are increasingly engaging in activities with bodies that go beyond the human form. The sense that a specific body part belongs to the self is referred to as body ownership, which is a key factor in how avatars shape self-perception and in social VR, where it supports feeling that one's body is engaging with others and society. However, for non-human body parts such as animal ears, it is difficult to infer appropriate movements and sensations from the existing human body, and it remains unclear what kind of sensory feedback improves body ownership. In this work, we focus on cat ears as a representative non-human body part and examine how body ownership changes under multimodal feedback that combines visual, haptic, and auditory cues. Methods We implemented a quiet, hair-mediated haptic system using a shape-memory-alloy actuator to mimic the movement of the cat's ears by pulling on the participant's hair. We also manipulated the perceived location of auditory feedback using participant-specific binaural recordings. We conducted a study with 24 participants under four conditions that combined the presence or absence of haptic stimulation with audiovisual spatial congruency versus incongruency. Results The results showed that, in subjective ratings, both haptic stimulation and auditory feedback designed to be perceived as received through the virtual cat ears significantly increased ownership of cat ears and referral of touch toward the location of the cat ears. Furthermore, presenting haptic stimulation significantly increased referral of audio toward the location of the cat ears. In contrast, none of the proprioceptive-drift measures showed significant effects, indicating a dissociation between subjective ownership and proprioceptive updating for non-innate body parts. Discussion Overall, our findings suggest that multimodal feedback contributes to enhancing subjective ownership of non-human body parts, while its sufficiency for incorporating such parts as spatially grounded representations within the body schema remains limited.