'Don't look at me in that tone of voice!' Disturbances in the perception of emotion in facial expression and vocal intonation by depressed patients
Authors: Luck, Peter; Dowrick, Christopher F
Source: Primary Care Mental Health, Volume 2, Number 2, 1 June 2004 , pp. 99-106(8)
Publisher: Radcliffe Publishing Ltd.
Abstract:Background Recurrence is common in depression. Moreover, each new depressive episode increases the risk of further recurrence, though the mechanism for this is unknown. In order to examine this effect further, this study investigated the possibility that depressed patients perceive nonverbal signals (facial expression and vocal intonation) of others in a negative light and that this negative bias is more severe in patients who have had previous episodes of depression, thereby worsening patients' sense of rejection, isolation and vulnerability to relapse.
Method Seventy-nine subjects were studied: 22 patients during their first depressive episode (index group); 27 patients who had experienced at least one previous episode (recurrent group); and 30 subjects with no previous psychiatric history (control group). Outcome measures were: indices of depression (Beck Depression Index (BDI)) and anxiety (Beck Anxiety Index (BAI)); subjects' ratings of intensity of positive and negative emotion perceived in ambiguous, schematic (line-drawing) faces; subjects' ability to categorise the emotional (prosodic) tone of voice used by an actress in a series of recorded vocal trials. Patients were tested at presentation to their general practitioner and again after about six weeks' antidepressant treatment.
Results Compared with controls, patients with major depression generally perceived less positive facial emotion (controls: 17% (8–26%) maximum intensity; patients: 8% (4–16%) maximum intensity (median (interquartile range (IQR)), P = 0.001) and saw more negative facial emotion (controls: 20% (13–26%) maximum intensity; patients: 28% (23–36%) maximum intensity, P = 0.001). They also categorised more vocal trials with a negative emotional bias (controls: 3% (2–7%) trials; patients: 9% (3–16%) trials, P = 0.002), and made more erroneous categorisations of vocal prosody than controls (controls: 12% (9–21%) trials; patients: 18% (14–29%) trials, P = 0.003). Compared with the index group, the recurrent group perceived significantly less positive emotion in the faces (index: 12% (7–17%) maximum intensity; recurrent: 4% (0–12%) maximum, P = 0.010). Recurrent cases also categorised significantly more vocal trials with a negative emotional bias (index: 6% (3–12%) trials; recurrent: 15% (6–18%) trials, P = 0.040). After six weeks' treatment with antidepressants there was a generalised improvement in the perceptual disturbances of the cases taken as a whole. There was now no significant difference between index and recurrent groups in any of the outcome measures.
Conclusions The results suggest that depressed patients have negative biases in their perceptions of non-verbal signals (facial expression and vocal tone). These disturbances were particularly severe in those who had experienced one or more previous depressive episodes, and could contribute to the increased vulnerability to recurrence in patients with a history of depression. The improvement in perceptual disturbances which was observed in all the patients after treatment suggests that these negative cognitive biases are not enduring, trait-like qualities, but probably secondary to depressed mood. These findings may find application in the cognitive therapy of depression whereby patients could learn to recognise their faulty perceptions of non-verbal social cues and modify their behaviour accordingly.
Document Type: Research Article
Publication date: 2004-06-01