Abstract
1. Three groups of patients who had recovered from their illness, and who showed virtually no symptoms, were tested. Nearly all had received drug treatment for at least a month, and many were still taking drugs. Of the 54 patients, 16 had been diagnosed as schizophrenic, and had been actively deluded in the past. Seventeen had been diagnosed as schizophrenic, but had not been actively deluded. The remaining 21 had not been regarded as schizophrenic.
2. A previous study, testing exactly similar groups prior to treatment, had found the deluded schizophrenics most overinclusive, the non-deluded schizophrenics slightly overinclusive, and the non-schizophrenics normal in this respect. In the present study, there were no significant differences between the three groups on the measure of overinclusion used, the Object Classification Test. Furthermore the subjects were, for all practical purposes, all within the normal range on this measure when compared with previously published data from normal people. It was therefore concluded that overinclusive thinking in schizophrenia is probably a symptom of the illness, and not a permanent personality characteristic of the individuals concerned.
3. Two new tests of overinclusive thinking, both involving the establishment of a perceptual “set”, were tried out to see if they were practicable. The results were negative in that in neither procedure was any set developed.
4. A measure of abnormal retardation was also used, derived from the Object Classification Test. Again, the three groups were not significantly different, nor did they differ from a previously published normal group. This suggests that abnormal retardation, also, is a symptom of the illness of psychotic patients, and not a permanent personality characteristic.