Abstract conceptualization in schizophrenia: a fundamental psychological deficit?

Wright (1975) has recently argued that impairment in abstract conceptualization is an important schizophrenic deficit. We contend that the data to which he refers are insufficient support for that conclusion. Although schizophrenics' performance on sorting tasks may be less efficient than that of some other groups, the significance of this finding is debatable. A differential deficit in conceptual ability has not been shown and the confounding effects of third variables have not been ruled out. In addition, the validity of sorting techniques in measuring abstraction has not been adequately established. These methodological issues have a more general applicability to the study of psychopathology. Appreciation of them and a more specific definition of "acceptable evidence" would reduce considerably the continuing state of confusion in research on psychological deficit.