[Experiments on perception in schizophrenia (author's transl)]

Acute and chronic schizophrenic subjects were tested with 6 simple experimental tasks of visual stimulus selection. The 2 control groups were a group of non-psychiatric subjects and one of patients with other psychiatric diagnoses. The 6 experimental tasks represented three different types of attention: 1) differentiation between "figure" and "background", 2) concentration; 3) visual integration (Gestalt completion). The main result was that the acute group with paranoidal psychosis and hallucinations made significantly more mistakes in figure-background differentiation (grouping of patterns). But there was no difference between this group and the other patients in the concentration tasks. Both schizophrenic groups performed more poorly in the Gestalt completion task. The results are discussed in light of the information theory (breakdown of a hypothetical filter mechanism) and Sokolow's psychophysiological model of stimulus selection. The hypothesis is put forward that in the acute schizophrenic group a disturbance in an arousal-modulation system is responsible for attenuation of irrelevant input.