Backward masking performance as an indicator of vulnerability to schizophrenia.

Several types of design have been used to identify neurocognitive measures that indicate vulnerability to schizophrenia rather than the presence of the illness. These designs include studies of first-degree relatives of patients, studies of patients in symptomatic remission, and studies of subjects who are considered to be prone to psychosis. The backward masking procedure is one promising indicator of vulnerability to schizophrenia. Backward masking is a procedure in which identification of an initial stimulus (the target) is disrupted by a later stimulus (the mask). Schizophrenic patients show performance deficits on backward masking. Unaffected siblings of patients, remitted patients, and individuals prone to psychosis also show performance deficits on backward masking. This pattern of results suggests that backward masking is a promising indicator of vulnerability to schizophrenia. It provides an alternative phenotype for schizophrenia that is separate from the disorder. The composite nature of masking procedures helps investigators to parse a performance deficit into its smallest meaningful elements and relate them to vulnerability to schizophrenia.