word count: 261 34 35 Main Text Word Count: 5512 Abstract 46Background: One aspect of selfhood that may have relevance for Borderline Personality 47 Disorder (BPD) is variation in sense of body ownership. We employed the rubber hand illusion 48 (RHI) to manipulate sense of body ownership in BPD. We extended previous research on 49 illusory body ownership in BPD by testing: 1) two illusion conditions: asynchronous & 50 synchronous stimulation, 2) relationship between Illusion experience and core BPD symptoms, 51 and 3) relationship between illusion experience maladaptive personality traits.
53Methods: Participants (24 BPD, 21 control) underwent RHI procedures. We measured illusion 54 strength (questionnaire responses), proprioceptive drift (perceived shift in physical hand 55 position), BPD symptoms (DIB-R score), and maladaptive personality traits (PID-5).
57Results: For subjective illusion strength, we found a main effect of group (BPD > HC, F = 11.94 58 p = 0.001), and condition (synchronous > asynchronous, F(1,43) = 22.80, p < 0.001). There was 59 a group x condition interaction for proprioceptive drift (F(1,43) = 6.48, p = 0.015) such that 60 people with BPD maintained illusion susceptibility in the asynchronous condition. Borderline 61 symptom severity correlated with illusion strength within the BPD group, and this effect was 62 specific to affective symptoms (r = 0.481, p < 0.01). Across all participants, trait psychoticism 63 correlated with illusion strength (r = 0.481, p <0.01).
65Conclusion: People with BPD are more susceptible to illusory body ownership than are healthy 66 controls. This result is consistent with the robust clinical literature describing aberrant physical 67 and emotional experience of self in BPD. A predictive coding interpretation of these results 68 holds promise to develop testable mechanistic hypotheses for experiences of disrupted bodily 69 self in BPD. 70 71 72 73 74 75 76 77 78 79 3 1. Introduction 80 1.1. The embodied self in Borderline Personality Disorder 81 1.1.1. Self-disturbance is a core feature of BPD 82 Aberrations of self-experience and identity are considered a core symptoms of 83 Borderline Personality Disorder (BPD) [1]. Self-disturbance is characterized by a markedly 84 persistent unstable sense of self that can be realized by dramatic shifts in self-image, shifting 85 goals and values, and feelings of emptiness, dissociation, and non-existence [2, 3]. These 86 experiences are distressing and dangerous; in a qualitative study, Brown et al. [4] found that 87 more than 50% of women with BPD and history of self-harm endorsed disturbances in self-88 experience, such as emptiness, numbness, or feeling dead, as reasons for non-suicidal self-89 injury . 90 91 1.1.2. Bodily experience is disrupted in BPD 92 One aspect of selfhood that may have relevance for pathologies of self in BPD is the experience 93 of body ownership. Indeed, abnormal bodily experiences in BPD are common, including bodily 94 dissociation [5], altered pain perception [6],and deficits in interoception...