Choice reaction times in depressive states.

An experiment was performed in which two components of response latency, decision time (DT) and movement time (MT), were measured in two relatively homogeneous samples of neurotic and psychotic depressive patients, together with a normal control group. It was found that whereas both DT and MT were significantly longer in the depressive samples than in the control sample, only DT was significantly longer in the psychotic than in the neurotic depressive sample. Thus while both DT and MT were elevated among the depressive samples relative to the control sample, only DT was further sensitive to clinical variations within the depressive state. DT was found to increase directly with depressive severity among an undifferentiated sample of acute depressives, which on further analysis proved to hold for the neurotic depressive sample only. MT was found to increase directly with age among the psychotic depressive sample. No other age influences were found on response latencies of depressive patients. These results are discussed in terms of a postulated impairment of the central information-processing mechanisms, as an explanation of psychomotor slowing among depressive patients.