An experiment was conducted to determine whether depressed borderline patients could be distinguished from normal controls and psychotic patients on the basis of a visual backward masking task that measures speed of information processing. Results showed that a) borderline patients could not be distinguished from normal controls on the information-processing task; b) both the borderline patients and the normal controls were superior to psychotic patients with diagnoses of major depressive, schizoaffective, and manic disorders; and c) among the three psychotic groups, the schizoaffective subjects were the most impaired.The data support the idea that borderline patients have normal-range information-processing functions. In distinction, all three psychotic groups showed disruption of this fundamental ego function by which information is processed. The results of related experiments indicate that schizotypal patients (in distinction to borderline patients) are abnormal information processors. Taken together, these findings support the contention that the schizotypal/borderline distinction is valid.