Cogno-Vest: A Torso-Worn, Force Display to Experimentally Induce Specific Hallucinations and Related Bodily Sensations

Abstract

Recent advances in virtual reality and robotic technologies have allowed researchers to explore the mechanisms underlying bodily aspects of self-consciousness which are largely attributed to the multisensory and sensorimotor processing of bodily signals (bodily self-consciousness, BSC). One key contribution to BSC, that is, currently poorly addressed due to the lack of a wearable solution, concerns realistic collision sensations on the torso. Here, we introduce and validate a proof-of-concept prototype of the torso-worn force display, the Cogno-vest, that provides mechanical touch on the user’s back in a sensorimotor perception experiment. In a first empirical study, we characterized human finger poking ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N=28$ </tex-math></inline-formula> ). In order to match these poking characteristics and meet the wearability criteria, we used bidirectional, push–pull solenoids as a force actuator in the Cogno-vest. Subsequently, and based on an iterative design procedure, a body-conforming, unisex, torso-worn force display was prototyped. Finally, we conducted a behavioral study that investigated BSC in 25 healthy participants by introducing conflicting sensorimotor signals between their hands and torso (back). Using the final reiteration of the Cogno-vest, we successfully replicated previous findings on illusory states of BSC, characterized by presence hallucinations (PH) and passivity symptoms, and achieved higher illusion ratings compared to static conditions used in prior studies.