Impaired detection of visual motion in schizophrenia patients.

PURPOSE: A recent report demonstrated impaired auditory detection and discrimination in schizophrenia patients. It is suggested that a deficit in attention resulted in flatter slopes of the psychometric functions. Here, we investigated whether these patients showed a similar deficit in another sensory modality. Specifically, we examined a subset of the schizophrenia patients in a visual task involving motion detection.
METHODS: A total of 13 schizophrenia patients and 14 normal controls detected the presence of a group of random dots moving in a coherent direction among other dots moving in random directions. Signal intensity varied from trial to trial. Detection sensitivity and bias were computed using signal detection theory.
RESULTS: The schizophrenia patients were less sensitive in detecting motion stimuli, compared to normal subjects. The decrement in sensitivity varies with signal-to-noise ratio. The two groups did not differ in response bias.
CONCLUSION: Schizophrenics were impaired in visual, as well as in auditory, attention, in accordance with the idea that attention impairment may represent a core deficit in schizophrenia.