Squeezed and Released Self: Using a Squeeze Machine to Degrade the Peri-Personal Space (PPS) Boundary

The squeeze machine is a V-shaped device that applies pressure to the user's entire body to encourage relaxation, especially in individuals with autism. Thus far, this device has only been used for therapy; however, by experiencing the balance of "to squeeze" and "to be squeezed" throughout the body, the transformation of the user's bodily self-consciousness can be expected. Here, we estimated these changes by measuring the peri-personal space (PPS) using a preestablished cross-modal (auditory and tactile) task in neurotypical adults. As a result, the PPS boundary, which was clear in the control condition, was degraded during the squeeze machine experience, even though participants subjectively reported no difference in their impressions of the auditory stimuli between the two conditions. This result points to the modification of the implicit relationship between the self and the external world in terms of the PPS.