A process-oriented approach for averting confounds resulting from general performance deficiencies in schizophrenia.

The most pervasive and least well-addressed problem in cognitive studies of schizophrenia is the propensity of schizophrenia patients to show inferior performance on a variety of cognitive tasks. Consequently, apparent specific cognitive abnormalities may actually reflect the interaction of task discriminating power with generalized deficit. L. J. Chapman and J. P. Chapman (1973a) suggested psychometric approaches for eliminating such artifactual group differences. Unfortunately, their solution neglects important issues of process specification and does not provide a viable strategy for process-oriented investigators. Psychometric remediation of artifactual Group x Task interactions inevitably confounds the processes being measured, resulting in theoretically ambiguous findings. Moreover, evidence that changes in measurement reliability can both increase and decrease group discrimination challenges a basic underlying assumption of the Chapmans' matching solution. This article presents a process-oriented approach to solving this problem in schizophrenia research.