Psychometric characteristics of ideational retardation in depressives

In two studies we tested the assumption that slowing of ideation (the ideational counterpart of psychomotor retardation) reflects a dimension distinct from severity of depression. Specifically, we hypothesized that an objective measure of ideational retardation would be correlated with a psychomotor retardation rating scale but not with a depression severity rating scale. There was in-patients in Study 1 and 30 out-patients in Study 2; all satisfied DSM-III criteria for major depressive episode. Measurements of ideational retardation, and notably latency of response, were derived from patient responses to the Rorschach plates (Study 1) and to simplified non-figurative line drawings (Study 2). As expected, results showed that latencies of response were not significantly correlated with depression severity scores on the Montgomery and Asberg Depression Rating scale (r = .19 in Study 1, r = -.08 in Study 2), but were significantly correlated with the scores on the Salpétrière Retardation Rating Scale (subscale for observable items, SRRSo)(r = .71, p < .0005 in Study 1; r = .55, p < .005, in Study 2).