Increased critical stimulus duration among nonpsychotic subjects with Minnesota Multiphasic Personality Inventory 2-7-8 profiles in the Merritt and Balogh letter-discrimination procedure is consistent with the view that this abnormality might be a vulnerability indicator for a poor prognosis, chronic type of schizophrenia. However, the procedure that Merritt and Balogh used to measure critical stimulus duration is likely to involve higher load on processing capacity than the procedure used by Braff and Saccuzzo with patients who showed schizotypal personality disorder. Thus, consistent with our hypothesis, the Merritt and Balogh procedure appears more likely to detect a deficit among persons at risk for schizophrenia than procedures that involve little or no demand on processing capacity.