Reduced Jumping to Conclusion Bias after Experimentally Induced Enhancement of Subjective Body Boundaries in Psychosis

Abstract

Introduction: A disturbed sense of self is frequently discussed as an etiological factor for delusion symptoms in psychosis. Phenomenological approaches to psychopathology posit that lacking the sense that the self is localized within one’s bodily boundaries (disembodiment) is one of the core features of the disturbed self in psychosis. The present study examines this idea by experimentally manipulating the sense of bodily boundaries. Methods: Seventy-three patients with psychosis were randomly assigned to either a 10-min, guided self-massage in the experimental group (EG) to enhance the sense of bodily boundaries or a control group (CG), which massaged a fabric ring. Effects on an implicit measure (jumping to conclusion bias; JTC) and an explicit measure (Brief State Paranoia Checklist; BSPC) of delusion processes were assessed. The JTC measures the tendency to make a decision with little evidence available, and the BSPC explicitly measures the approval of paranoid beliefs. Results: Patients in the EG showed a lower JTC (M = 4.11 draws before decision) than the CG (M = 2.43; Cohen’s d = 0.64). No significant difference in the BSPC was observed. Discussion/Conclusion: Our results indicate that enhancing the sense of body boundaries through a self-massage can reduce an implicit bias associated with delusional ideation and correspondingly support the idea that disembodiment might be a relevant factor in the formation of psychotic symptoms.

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Gait Patterns and Mood in Everyday Life: A Comparison Between Depressed Patients and Non-depressed Controls

“…Several lines of research suggest embodiment processes to be highly relevant for understanding cognitive and emotional processes in MDD. Only recently, more attention has been drawn on research on embodiment effects in the context of psychological disorders, mostly with respect to major depressive disorder (MDD), but also other disorders such as schizophrenia (Tschacher et al 2017;Lyons et al 2021). Some of these studies have focused on the effects of the motoric system on memory bias in major depressive disorder (MDD).…”