Two-flash Threshold, Sensitivity and β in Normal Subjects and Schizophrenics

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Abstract
Two-flash threshold, response criterion, and sensitivity (defined by the slope of the psychophysical ogive), were examined in schizophrenics and in normals under three conditions—a base-line condition, and during and after continuous white noise. Schizophrenics were subdivided into four groups on the basis of whether or not they exhibited paranoid symptomatology and electrodermal orienting responses. In general schizophrenics had more lenient two-flash response criteria than normal subjects. In the base-line condition schizophrenics with orienting responses had lower two-flash thresholds than those without orienting responses. Paranoid schizophrenics had more lenient criteria than non-paranoid schizophrenics and lower sensitivity than the non-paranoid group with orienting responses. Differential group effects were obtained during and after noise, especially with regard to sensitivity.