The Wechsler Adult Intelligence Scale (WAIS), but not the Defence Mechanism Test (DMTm), separates schizophrenics and normal controls in a factorial cluster analysis

Ten schizophrenic patients and ten healthy control subjects matched with respect to sex, age and education were tested by a psychological test battery including WAIS, WCST, FAS and a modified version of the tachistoscopic Defence Mechanism Test (DMTm). In a Q-factor analysis two factors were derived in the analysis of DMTm test scores. The distribution of cases among these factors was wholly at random. On the other hand, when analysing WAIS scores, five factors were derived and schizophrenic cases as well as control subjects were almost unequivocally clustered by different factors. It is argued that also if an unequivocal categorisation of cases had been achieved in the analysis of DMTm data, such a finding might well have been interpreted as an effect of anomalies in cerebral structures assumed to be of critical importance in the filtering of signals in the stream of visual perception. The existence of such anomalies in schizophrenics is now well established by neuroimaging as well as postmortem studies, and findings are also well in accordance with phenomenological and physiological data. The failure of DMTm to separate schizophrenic and control subjects does thus make the second and important step in a discussion on validity entirely superfluous, namely whether signs recorded really measure what they are assumed to measure, in this case defence mechanisms in a psychoanalytic sense.