Flicker sensitivity and response bias in psychiatric patients and normal subjects.

Abstract

The flicker thresholds of 26 psychiatric patients and 26 normal Ss [subjects] obtained by 3 psychophysical procedures were analyzed within the context of sensory (statistical) decision theory. The method-of-limits threshold of the patients was significantly higher (p<.01) than that of the normals, yet the forced-choice thresholds of these same Ss did not differ. Since the traditional thresholds have been demonstrated to be a function of both S''s sensory sensitivity (d[image]) and his response bias or subjective criterion, Xc, while the forced-choice threshold is purely a function of d[image], it may be concluded that patients and normals differed only with respect to response bias. An order interaction effect (p<.01) demonstrated that patients adopt a less conservative attitude as a result of experience with the test situation, one which coincides with that of the normal Ss.