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Self-disturbances such as an anomalous perception of one’s own body boundary are central to the phenomenology of schizophrenia (SZ), but measuring the spatial parameters of the hypothesized self–other boundary has proved to be challenging. Peripersonal space (PPS) refers to the immediate zone surrounding the body where the self interacts physically with the environment; the space that corresponds to hypothesized self–other boundary. PPS is represented by enhanced multisensory integration and faster reaction time (RT) for objects near the body. Thus, multisensory RT tasks can be used to estimate self–other boundary. We aimed to quantify PPS in SZ using an immersive virtual reality visuotactile RT paradigm. Twenty-four participants with SZ and 24 demographically matched controls (CO) were asked to detect tactile vibration while watching a ball approaching them, thrown by either a machine (nonsocial condition) or an avatar (social condition). Parameters of PPS were estimated from the midpoint of the spatial range where the tactile RT decreased most rapidly (size) and the gradient of the RT change at this midpoint (slope). Overall, PPS was smaller in participants with SZ compared with CO. PPS slope for participants with SZ was shallower than CO in the social but not in nonsocial condition, indicating an increased uncertainty of self–other boundary across an extended zone in SZ. Social condition also increased false alarms for tactile detection in SZ. Clinical symptoms were not clearly associated with PPS parameters. These findings suggest the context-dependent nature of weakened body boundary in SZ and underscore the importance of reconciliating objective and subjective aspects of self-disturbances.

Background Schizophrenia has been suggested to be a disorder of social communication, which depends on the way language is used to convey thoughts, beliefs, feelings, and intentions. Everyday language can also reveal personality, emotions, and social skills of the speaker. Extensive past research affirms the central importance of language and thought disorder as diagnostic features of schizophrenia, mostly focused on the neurocognitive aspects of language output collected during clinical interviews, and not on the social nature of language. In this study, we examined narratives written in response to viewing social scenes by individuals with schizophrenia (SZ) and matched controls (CO) using an automated computational linguistics and statistical-based text analysis tool that computes socially-relevant variables. Methods 23 individuals with schizophrenia (SZ) and 23 demographically matched controls (CO) were shown paintings of social situations, and were asked to write reflections describing what they thought and felt about these scenes. Two pictures were presented consecutively. There was no time limit. Resulting narratives were analyzed with the Linguistic Inquiry and Word Count program (LIWC; Pennebaker et al, 2015). LIWC computes basic linguistic variables such as the % of self-referring and non-self-referring pronouns, social and emotion words, and cognitive items. LIWC also generates 4 complex variables: formal and logical thinking patterns (“analytic”); social status or confidence (“clout”); authenticity, and emotional tone. Clinical symptoms in SZ were assessed using the Scale for the Assessment of Positive Symptoms (SAPS) and the Scale for the Assessment of Negative Symptoms (SANS). For all participants, the UCLA Loneliness Scale, the National Adult Reading Test (NART), and the Edinburgh Handedness Inventory (EHI) were administered. Results The two groups did not differ in NART or EHI. There was no group difference in the number of words produced. SZ produced greater number of pronouns than CO but this effect was driven by a higher % of self-referring pronouns in SZ than CO, with no group difference in non self-referring pronouns. For complex variables, CO scored significantly higher in authenticity than SZ but no group differences were observed in clout, analytics, or emotional tone. Loneliness was higher in SZ compared with CO. There were no other significant group differences. In SZ, pronoun use was correlated with positive symptoms (especially with ratings of hallucinations, bizarre behavior, delusions of mind-reading and thought broadcasting) and inversely correlated with negative symptoms (avolition, apathy and motor retardation). Social words were inversely correlated with SAPS Thought Disorder. Clout was inversely correlated with SANS Alogia and SAPS Thought Disorder. Authenticity was correlated with SANS Anhedonia and Asociality. In CO, loneliness was correlated with the % negative emotion words and NART was correlated with total number of emotion words. Discussion We used an automated linguistic analysis tool to extract information relevant to social communication from written narratives. We found group differences in the use of pronouns and authenticity. We also observed associations of clinical symptoms with certain social aspects of language use in schizophrenia. One advantage of automated text analysis tools is the minimization of implicit biases inherent in ratings of interviews. Limitations of this study include lack of direct social functioning measures and the sample size. Future work will incorporate linguistic text analysis within a social paradigm to directly examine the role of language use in social functioning.

BACKGROUND: An implicit understanding of one’s body with fixed boundaries allows us to differentiate self from other. However, individuals with schizophrenia (SZ) frequently report experiencing bodily self-disturbances such as sudden changes in size and shape of the body and flexible or porous body boundary. In order to quantify bodily disturbances in schizophrenia, we investigated the construct of peripersonal space (PPS), which represents the ‘near’ space immediately surrounding our bodies. Whilst the physical body boundary is fixed, the neural representation of PPS is plastic and can be estimated using multisensory integration paradigms. Moreover, the size and extent of the PPS is thought to be influenced by the social-emotional environment, which in turn has implications for social interactions. We sought to measure PPS in SZ and control participants (CO) by adopting a multisensory integration task in a virtual reality (VR) environment to test whether PPS is altered in SZ when compared to CO. In addition, we examined the effects of social context and threat on the plasticity of PPS. METHODS: SZ and demographically matched CO participated in a visual-tactile response time (RT) task in immersive VR. Participants wore a head-mounted display and trackers on their feet, hands, and the torso. Handheld controllers were used to deliver tactile vibration and to record RTs. In VR, participants faced either an avatar or a machine that threw a ball at a speed of 3m/s. In addition to this visual display, tactile vibration was delivered to the participant’s hand via the controller at one of five set distance points from the initiation of the ball pitch. Participants were asked to press a trigger on the controller as soon as they felt a vibration. There were two social conditions (ball thrown by a person or a machine) and two emotion conditions (threat versus no threat). The RTs were recorded. According to Serino et al (2018), visuo-tactile integration would facilitate the RT nearer one’s PPS boundary. We calculated the location where the visuotactile facilitation occurs to estimate the boundary of PPS. In addition, we examined positive and negative symptoms, social isolation, and social functioning. RESULTS: PPS boundary in SZ differed significantly from that of the CO. However, there were a range of individual differences in PPS within groups. RTs were faster for threat than non-threat stimuli. The impact of social context was not conclusive. DISCUSSION: Preliminary results suggest that PPS can be estimated in VR and that PPS is altered in SZ. Given the importance of PPS in the construction of social self, anomalous experience of PPS in SZ may contribute to self-disturbances. Moreover, individual differences in PPS might impact social interactions and hence contribute to social impairments in schizophrenia.

Background: Implicit theory of mind (iToM) is part of early social development (Schneider et al, 2012). It is crucial for building sensitivity to the other person or event (Apperly and Butterfill, 2009) and for tracking the other’s mental states. This process occurs without conscious awareness (Low and Perner, 2012). Measuring iToM may be important for understanding and rehabilitating social cognitive impairments in people with schizophrenia. The Social Attribution Task–Multiple Choice (SAT-MC), which was first developed for studying people with autism, has been successfully employed to distinguishing individuals with schizophrenia (SZ) from healthy controls (HC) in iToM in western countries (Bell et al, 2010). Because it uses geometric shapes enacting a social drama, the stimuli are nonverbal and does not include culturally loaded materials compared to other social cognition measures. We therefore hypothesized that the SAT-MC would be valid for use in schizophrenia research across cultures.