title: Anomalous bodily experiences and perceived social isolation in schizophrenia: An extension of the Social Deafferentation Hypothesis.
abstract: Disturbances of the bodily self are fundamental to the phenomenological experience of individuals with schizophrenia, a population at risk for social isolation. Both proprioception and exteroception contribute to a sense of consistent body boundary that contains the self across time and space, and this process is influenced by self-other (social) interactions. However, the relationship between social isolation, exteroception, and in-the-moment changes in body representation has not been elucidated. We investigated susceptibility to anomalous bodily experiences with a phantom nose induction procedure that elicits a sensation that one's nose is changing (Pinocchio Illusion: PI) in relation to exteroceptive awareness and social isolation.
  
  
  
  25 individuals with schizophrenia (SZ) and 15 matched controls (CO) participated in a PI induction procedure to quantify susceptibility to bodily aberrations and a tactile discrimination task to assess exteroception. Clinical symptoms in SZ and schizotypy in CO were assessed, in addition to a self-report measure of perceived social isolation.
  
  
  
  Compared to CO, SZ showed increased PI and impaired tactile discriminability. SZ reported greater loneliness than CO. PI scores were correlated with increased loneliness and decreased tactile discriminability.
  
  
  
  Greater susceptibility to anomalous bodily experiences, together with reduced exteroceptive awareness and increased loneliness, is compatible with the framework of Hoffman's Social Deafferentation Hypothesis, which posits that a functional "amputation" from one's social environment could lead to a reorganization of the social brain network, resulting in hallucinations and delusions. These findings underscore the importance of the relationship between social isolation and self-disturbances in schizophrenia.
authors.affiliation: Department of Psychology, Vanderbilt University, 111, 21(st) Avenue South, Nashville, TN 37240, United States. Electronic address: jamie.c.michael@vanderbilt.edu.
authors.forename: Jamie
authors.initials: J
authors.lastname: Michael
authors.affiliation: Department of Psychology, Vanderbilt University, 111, 21(st) Avenue South, Nashville, TN 37240, United States. Electronic address: sohee.park@vanderbilt.edu.
authors.forename: Sohee
authors.initials: S
authors.lastname: Park
mesh_terms: D000328:Adult; D001364:Awareness; D001828:Body Image / Q000523:psychology*; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D008297:Male; D010465:Perception; D011434:Proprioception; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000503:physiopathology; D012565:Schizophrenic Psychology; D012569:Schizotypal Personality Disorder / Q000523:psychology; D057566:Self Report; D012934:Social Isolation / Q000523:psychology*; D014110:Touch
keywords: Body aberration; Exteroception; Pinocchio Illusion; Proprioception; Self-disturbances; Social isolation