BACKWARD-MASKING DEFICIT IN ADOLESCENTS WITH SCHIZOPHRENIC DISORDERS OR ATTENTION-DEFICIT HYPERACTIVITY DISORDER

Objective: Backward masking is a cognitive task that involves the earl iest phases of visual information processing. Disrupted task performan ce caused by a visual mask has been found repeatedly in schizophrenic patients; however, the specificity to schizophrenia of deficits in bac kward masking has received only limited study. Method: In this study 2 0 patients with early-onset schizophrenic disorders were compared to 2 0 adolescents with attention deficit hyperactivity disorder (ADHD) and 30 normal adolescents on a two-digit identification task in three bac kward-masking conditions: no mask, a short stimulus interval (33.0 mse c), and a long stimulus interval (49.5 msec). Results: The performance of the two groups of patients was similar, and both groups showed a s tatistically significant masking deficit after the long stimulus inter val and a nearly significant deficit after the short stimulus interval in comparison with the normal subjects. Conclusions: Increased vulner ability to the masking stimulus tr,as confirmed in schizophrenic subje cts, but it is not specific to schizophrenia and is not accounted for by psychotic symptoms alone, since the subjects with ADHD performed si milarly.