| This study examined neural mechanisms underlying the expression and comprehension of prosodic emotion in brain-damaged and healthy control subjects. There were 54 participants: 18 normal controls (NCs), 17 individuals with left-sided damage (LBDs), and 19 individuals with right-sided damage (RBDs). There were no significant group differences for age, education, occupational status, or months post stroke onset. Using participants' posed output to examine prosodic expression, three positive and five negative emotions were analyzed for fundamental frequency (F0) mean, F0 standard deviation, and duration. Intensity and accuracy ratings were also obtained from trained judges. The relationship between acoustical parameters and raters' evaluations was determined. For comprehension, accuracy scores based on participants' responses to emotionally intoned sentences were analyzed. Results yielded limited support for the right-hemisphere hypothesis for emotional expression. However, when emotions were categorized by motoric direction or arousal level, the RBD group was rated as significantly less intense than the LBD group. The current study, however, yielded more support for the valence hypothesis. For positive emotions, the LBD group was rated as significantly less accurate than the RBD and NC groups. For negative emotions, RBDs were rated as significantly less accurate than LBDs and NCs. Across all emotions, no effects of group for any of the acoustic measures were found. However, RBDs were less appropriate in their F0 production for sadness and disgust than were NCs. For accuracy ratings, there was a significant main effect of group, such that LBDs were less accurate than NCs, suggesting that the LBDs might have had some linguistic problems processing the tasks conceptually. For intensity ratings, there was no main effect of group. However, RBDs were rated as less intense for fear and interest than were LBDs, and LBDs were less intense than RBDs and NCs for pleasant surprise. The current study also measured the relationship between acoustic analysis and human perception of emotion; results revealed that F0 mean semitone difference scores were positively correlated with judges' ratings of emotional intensity. This is important, as using a visual biofeedback system to improve emotional expression could have implications for treatment of emotional communication and interpersonal relationships. |
