Effects of Nicotine on Interpersonal Distance of Patients with Schizophrenia in Immersive Virtual Environments: a Preliminary Study

Kim, Eosu; Jang, Hee Jeong; Ku, Jeonghun; Kim, In Young; Kim, Chan Hyung; Kim, Jae Jin; Cho, Hyun Sang

Abstract

OBJECTIVE
Using immersive virtual environment technique, we aimed to preliminarily examine whether nicotine affects the interpersonal distance, as the size of personal space, in schizophrenic patients, which have extraordinarily high smoking rate. METHOD: Ten male schizophrenic patients who were at least moderate current smokers smoked a high (0.9 mg nicotine as an active drug) or low (0.1 mg nicotine as a placebo) nicotine-yielding cigarette after overnight-abstinence in randomized, double blind, cross-over design. Following the smoking session, subjects performed the 'self-introduction task' in virtual environment by introducing themselves consecutively to six different avatars, which varied in gender and facial/verbal expressions (neutral, angry, and happy). In the tasks, subjects were asked to step forward to each avatar until they felt most comfortable to greet the avatar first. The distance was measured by the head-tracking device, which was transmitting real-time data to the computer. Affective valence and arousal to each avatar were also rated by subjects following the tasks.
RESULTS
The overall interpersonal distance of the drug group was significantly greater than that of placebo group (Z = -2.93, p = 0.022). The distances with emotionally neutral avatars (male/female) of the six were significantly different between the two groups (Z = -2.19, p = 0.028 ; Z = -2.09, p = 0.037). Within-group analysis revealed a significant difference among the distances with the six avatars in the placebo group (x2 = 17.03, df = 5, p = 0.004), but there was no significant within-group difference in the drug group (x2 = 6.11, df = 5, p = 0.295).
CONCLUSION
These preliminary findings suggest that nicotine may increase the size of personal space of schizophrenic patients probably by enhancing the social stimuli perception through affecting the patients' cognitive function.