Br. Rund et al., BACKWARD-MASKING DEFICIT IN ADOLESCENTS WITH SCHIZOPHRENIC DISORDERS OR ATTENTION-DEFICIT HYPERACTIVITY DISORDER, The American journal of psychiatry, 153(9), 1996, pp. 1154-1157
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.