Schizophrenics Exhibit Abnormal Binocular Rivalry

Abstract:
When one eye views vertical stripes while the other views horizontal stripes, perception spontaneously alternates (rivals) between the two orientations. Patients with bipolar disorder have recently been reported to show an abnormally slow rivalry rate. We found that chronic schizophrenics (n=12) report rivalry alternation at about the same rate as do controls (n=35), with simulated rivalry control procedures yielding 70%-80% hit rates and 20%-30% false alarms. The distributions of schizophrenics' responses differ from those of controls, however. For 7 patients (subgroup A) response distributions were less peaked than those of controls, and showed unusually frequent "blended" or non-rivalrous percepts. The other 5 patients (subgroup B) evidenced bimodal response distributions, with one peak near that of the unimodal response distribution for controls (1.3 to 1.9 sec) and the other peak much shorter (0.25 to 0.3 sec), suggesting a relatively fast second process. We speculate that the neural timing involved in binding these alternating percepts is disrupted in schizophrenics. In subgroup A the timing appears more chaotic and the binding less crisply demarcated than in controls. In subgroup B both the normal timing and a much faster component seem to be involved. Perhaps the abnormal fast component is normally suppressed by inhibitory feedback that is weak in these patients. Supported by the Veterans Administration Research Service.