Visual 3D illusion: a systems-theoretical approach to psychosis.

Binocular depth inversion represents an illusion of visual perception. Such an inversion does not occur in all cases, especially when objects with a higher degree of familiarity (e.g. photographs of faces) are displayed. Cognitive factors are assumed to override the binocular disparity cues of stereopsis. We tested the hypothesis that during psychotic and similar states the human CNS is unable to correct the implausible perceptual hypothesis. Measurements of binocular depth inversion in perception of 3D objects were performed in schizophrenic patients (n = 13), in patients with alcohol withdrawal (n = 10), in sleep-deprived medical staff (n = 10) and in healthy volunteers (n = 41). The binocular depth inversion scores were highly elevated in the patient group and in the sleep-deprivated medical staff in comparison with healthy volunteers. The data demonstrate that impairment of binocular depth inversion reflects a common final pathway, characterized by an impairment of adaptive systems regulating perception.