Arousal responses to personal space intrusions in psychotic illness: A virtual reality study

Baktash Babadi; Katherine Dokholyan; Nicole R DeTore; Roger B H Tootell; Rachel F Sussman; Sarah L Zapetis; Daphne J Holt

doi:10.1016/j.schres.2024.09.004

Arousal responses to personal space intrusions in psychotic illness: A virtual reality study

Schizophr Res. 2024 Sep 20:274:158-170. doi: 10.1016/j.schres.2024.09.004. Online ahead of print.

Authors

Baktash Babadi¹, Katherine Dokholyan², Nicole R DeTore¹, Roger B H Tootell³, Rachel F Sussman², Sarah L Zapetis², Daphne J Holt⁴

Affiliations

¹ Department of Psychiatry, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA.
² Department of Psychiatry, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA.
³ Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA; The Athinoula A. Martinos Center for Biomedical Imaging, 149 13th Street, Charlestown, MA 02129, USA.
⁴ Department of Psychiatry, Massachusetts General Hospital, 55 Fruit Street, Boston, MA 02114, USA; Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA; The Athinoula A. Martinos Center for Biomedical Imaging, 149 13th Street, Charlestown, MA 02129, USA. Electronic address: dholt@mgh.harvard.edu.

PMID: 39305791
DOI: 10.1016/j.schres.2024.09.004

Abstract

Background: Prior studies have found that individuals with schizophrenia often have an enlarged "personal space". However, the neurocognitive mechanisms underlying this consistent finding remain unknown.

Methods: The well-validated Stop Distance Procedure was used to measure the personal space preferences of individuals with psychotic disorders (PD, N = 22) and demographically-matched healthy controls (HC, N = 20) in response to human and virtual (avatar) intruders. Physiological arousal and subjective discomfort were measured during intrusions into personal space and modeled across different interpersonal distances. Additionally, participants were interviewed to assess their subjective awareness of their personal space preferences.

Results: Personal space measurements with humans and avatars were highly correlated and reliable over repeated trials, and influenced by the displayed emotion and gender of the intruders, in both groups. The PD group exhibited a larger personal space than the HC group (all p < 0.028), and the size of personal space with avatar intruders was significantly correlated with positive symptom severity in the PD subjects. Moreover, the magnitude of arousal responses to personal space intrusions was proportional to a power (exponent) of the distance between subjects and intruders, with a significantly smaller exponent in the PD (compared to the HC) for both human (p = 0.026) and avatar (p = 0.011) intruders, indicating a less steep function. Lastly, much of the participants' qualitative impressions of their personal space behaviors were consistent or correlated with the quantitative findings, reflecting some awareness of the determinants of personal space.

Conclusions: These findings reveal both intact and altered aspects of personal space regulation in psychotic disorders, and the potential utility of personal space measurements, given their high reliability, to serve as objective targets of interventions.

Keywords: Personal space; Psychotic disorders; Schizophrenia; Self-disturbance; Virtual reality.

Publication types

Review