Gaze direction determination in schizophrenia

It has been proposed that an impairment in gaze determination is responsible for the paranoid symptoms reported in schizophrenia. To address this, we examined the gaze discrimination system in schizophrenia. Thirty-two patients suffering from schizophrenia (20 patients with persecutory delusions and 12 patients without such delusions) were compared to 32 control subjects on two specific tasks. In the first task, the subjects had to determine whether 130 portraits were looking right or left. In the second task the subjects were asked to determine whether or not 130 portraits were looking at them. The absolute threshold of difference used to investigate the influence of instruction on gaze discrimination did not show any difference between patients with schizophrenia, whatever paranoid or not, and control subjects. Paranoid patients, as well as controls, displayed a significantly finer discrimination threshold in the right vs. left judgment than in the self vs. non-self judgment. Subjects with schizophrenia were able to discriminate gaze direction in the two tasks, but they took significantly more time in the task requiring to determine the presence or the absence of a mutual gaze contact than in the other one, whereas controls took the same duration to elicit both tasks. These data are consistent with those reporting that perceptual abilities are spared in schizophrenia while delusions are related to an impairment of a higher level of analysis.