Automatic speech rate as an index of depression and its relationship to psychological and motor tests

Abstract

The value of the automatic speech rate as an index of depression was investigated. Sixteen hospitalized depressed patients (ten diagnosed as suffering from Endogenous Depression and six with Reactive Depression) and 16 normal subjects were compared on rates of automatic speech and tests of psychomotor speed. In addition the patient group was assessed on three measures of depression. Members of each group were tested weekly, the depressed patient group until discharged from hospital, the normal group for three consecutive weeks. Five weeks later, a 'follow-up' test was given to both groups. On every test day, excepting 'follow-up', the assessments were made at morning and afternoon tests sessions in order to investigate the diurnality of responses. A repeated measures design was employed to facilitate comparison of scores over time. The results showed a statistically significant difference between the depressed group and the normal group on measures of automatic speech. The depressed group showed statistically significant improvement on automatic speech rates with concomittant significant improvement on the clinical scales. The normal subjects also demonstrated a significant change in automatic speech rates over time and both groups showed diurnal variation on this measure. The depressed and normal groups could be differentiated from one another on tests of psychomotor speed. These results indicate that the automatic speech rate is a potentially useful measure for investigating and monitoring depression. Suggestions for further investigations are made, particularly those which study the effect of mental set on automatic speech rates.