Discrimination and response bias in memory: effects of depression severity and psychomotor retardation

Although memory disorders have been well documented in depression, there is controversy concerning depressives' performance on recognition memory tasks; e.g. whether they have impaired discrimination and conservative or liberal response bias according to signal detection theory. In addition, symptomatic correlates of discrimination and response bias indices have been lacking. A word recognition memory task analyzed according to the two high threshold theory was administered to 26 depressives and 26 controls. Depressives obtained a lower index of discrimination (Pr) than controls. The index of response bias (Br) was not different between groups. In the depressed group, overall severity of depression was related to discrimination, whereas psychomotor retardation level was related to response bias. Cognitive performance of depressives could be advantageously analyzed in terms of these two dimensions of symptomatology.