Augmented Bodily Self in Performing a Button-Touching Task with Soft Supernumerary Robotic Arms

Extra or supernumerary robotic limbs are actively exploited in the field of body augmentation. The science of self-recognition of additional body parts is an interesting subject. Although the field is primarily led by psychological studies in virtual reality, which facilitate flexible experimental designs, we believe that assessments employing real robots are also essential. In this study, we investigated the sense of body ownership and agency of a dual-arm wearable robotic arm using an inexpensive and safe inflatable structure. We report the results of functional near-infrared spectroscopy (fNIRS) analysis of brain activity during the use of the robotic arm. The questionnaire results from the experiment, which involved a button-touching task, revealed that both the sense of ownership and sense of agency were significantly higher in the goal-oriented collaborative experience compared to the non-goal-oriented condition. This indicates that humans feel ownership of and agency toward an autonomous robot or a remote-controlled robotic arm operated by another person. The analysis of the fNIRS data included a two-factor analysis of variance for the learning and trial phases. While there was no main effect for the conditions within each phase, a significant interaction was observed between the two brain regions of the right angular gyrus and right postcentral gyrus.