Objectives:
The aim of the research was to explore the susceptibility to disturbances in one’s sense of body ownership induced in patients with schizophrenia. The research questions were: 1) Is Rubber Hand Illusion (RHI) significantly more intense in a group of patients with schizophrenia than in a group of patients without a diagnosed mental illness? 2) Is there a correlation between disturbances in the sense of body ownership and the personality organization level, reflected in defense mechanisms? 3) Do the disturbances in the sense of body ownership correlate with the most common defense mechanisms?

Methods:
64 people took part in the study, including 31 patients with diagnosed schizophrenia, according to ICD-10 (93.5% – paranoid type and 6.5% – disorganized type) and 33 people without mental illness diagnosis. The study was conducted in the RHI paradigm. Research tools used: Botvinick and Cohen’s RHI Questionnaire and Bond’s Defense Style Questionnaire.

Results:
There were significant differences between the control group and the schizophrenic group: 1) in the intensity of RHI (F(1, 62) = 121.86; p < 0.001), as well as 2) on the neurotic (F(1, 62) = 28.21; p < 0.001) and immature (F(1, 62) = 36.71; p < 0.001) mechanisms’ level. Patients witch schizophrenia activated immature mechanisms most intensively while in the control group the dominant mechanisms were from the mature and neurotic groups.

Conclusions:
Patients with schizophrenia experience disruptions in the sense of body ownership much more intensively compared to the control group. The intensity of RHI is related to the personality organization level and to the most common activation of mechanisms from immature group, especially schizoid fantasy and projection.