Visual perceptual organization in schizophrenic patients.

Place & Gilmore (1980) proposed that schizophrenic patients are deficient in the perceptual organization of visual stimuli. According to their theory, the patients should be less influenced by global characteristics of visual displays. In the present experimental approach, 24 schizophrenics, 12 alcoholics and 24 healthy controls were asked to identify the number of lines presented for 23 ms on a video screen. In one condition, the stimuli were identical to those used by Place & Gilmore: up to six lines were shown at the corners of an imaginary hexagon; all lines were either in the same direction ('homogeneous') or differed in orientation ('heterogeneous'). In another condition the lines appeared at 10 different positions within the same field. The results of Place & Gilmore were not replicated; schizophrenics were only less influenced than the control group by different directions of the lines when three lines were presented. When more lines were presented, schizophrenics had the same advantage from homogeneity as the controls. If the basic configuration was a hexagon and six lines were presented, schizophrenics were able to profit very strongly from the global Gestalt. In summary, global characteristics of the visual displays do not facilitate visual information processing by schizophrenics as they do in the case of controls. However, if the basic Gestalt properties are strong enough, schizophrenics can take advantage of it. Thus the deficit of schizophrenics described by Place & Gilmore is relative and not absolute.