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

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.