Decomposing the corpus of neuropsychological tests

This commentary has had two primary concerns: We have attempted to address the difficulties and possibilities of using cognitive tests to measure the underlying biological basis for mental disorders. In particular, we have argued that to understand and interpret test results in psychiatry appropriate models of cognitive brain operations on a process-analytic level rather than on a psychometric level are essential. We have also discussed particular results of Abbruzzese et al.'s study, pointing out alternative interpretations of their perseveration results and some preconditions for demonstrating a true double dissociation. Rather than proceeding from the assumption of a unitary disease entity, we prefer to view "schizophrenia" as heterogeneous in its neuropathological and cognitive processing substrates, reflected in Bleuler's term "the schizophrenias."