Perception of visual-tactile asynchrony, bodily perceptual aberrations, and bodily illusions in schizophrenia

Body perception can be dramatically altered in individuals with schizophrenia resulting in experiences of undefined bodily boundaries, loss of body ownership, and size changes for parts of the body. These individuals may also be more susceptible to the rubber hand illusion (RHI: an illusion of body perception that can also be induced in neurotypical populations), but the findings are mixed. Furthermore, the perception of timing information about multisensory stimuli, which is thought to be fundamental for body perception, has been reported to be altered in schizophrenia. We tested here whether altered perception of the temporal relationship between visual and tactile signals in schizophrenia can predict self-reported perceptual aberrations and RHI susceptibility (indexed by both illusion self-ratings and a more objective proprioceptive-drift measure). We found that the sensitivity to detect temporal asynchronies is reduced in schizophrenia and this predicts bodily perceptual symptoms. In contrast, we found no evidence for a direct relationship between asynchrony detection sensitivity and RHI susceptibility. Instead, our findings suggest that experiencing more bodily perceptual symptoms increases the likelihood of endorsing unusual bodily experiences, resulting in higher RHI self-ratings but not higher proprioceptive-drift scores. Overall, our findings provide evidence for both direct and indirect links between temporal and body perception and thus new insight into the mechanisms that may underlie unusual body perceptions in schizophrenia.