Early visual information processing and the Defence Mechanism Test in schizophrenia

The aim of this study was to determine whether impairment in visual information processing measured by backward masking was related to high threshold values in the Defence Mechanism Test (DMT) in patients with schizophrenia.

A total of 20 patients with schizophrenia according to DSM-IV, most of whom were out-patients, were studied with backward masking and a modified version of the DMT (DMTm).

Nine of the patients showed an impairment in backward masking. There was a relationship between impairment in backward masking and the DMTm with either no or a late C-phase (correct perception in DMTm) in the first series, and a late perception of the peripheral person in the second series. There was no relationship for the other 14 threshold values. The patients did not have high threshold values in the DMTm as was expected.

In this sample consisting mainly of out-patients, there were few relationships between impairment in backward masking and high threshold values in DMTm. Their visual information processing was not as disturbed as expected. Most previous studies on both backward masking and the DMT in patients with schizophrenia have been conducted among in-patients, who could be expected to be more disturbed than the out-patients in the present study. The results of studies on in-patients with schizophrenia must not be generalized to include out-patients, and vice versa.