Role of autonomic arousal in stuttering

Christine Maria Weber, Purdue University

Abstract

Emotional factors have long been central to theories of stuttering, however the role of these factors in the disorder is still a matter of speculation. One approach to studying the relationship between emotional factors and stuttering is to measure physiological changes that are associated with emotion. Many of the physiological changes characteristic of emotional experiences are mediated by the autonomic nervous system, and autonomic processes are integrated with somatic processes at many levels of the nervous system. Somatic motor processes essential for speech production, for example respiration, are known to be influenced by autonomic activity. Assessment of autonomic nervous system activity during speech therefore may increase our understanding of how emotional factors could influence speech motor control processes in stuttering. The present investigation was designed to test two hypotheses: (1) autonomic arousal is greater in stutterers than normal speakers for speaking tasks, and (2) in stutterers, higher arousal is related to disfluent speech. Simultaneous measures of electrodermal activity, peripheral blood flow, and heart rate were obtained for 19 stutterers and 19 normal speakers performing speech and nonspeech tasks. The results indicate that autonomic arousal exhibited by stutterers for reading and spontaneous speech is not abnormally high, instead, it appears that speaking is associated with relatively large increases in sympathetic activity in both stutterers and normal speakers. The range of autonomic measures for speech tasks in large for both groups, but in stutterers the more extreme increases in arousal are related to a greater likelihood of the occurrence and increased severity of disfluent speech. Significant correlations between autonomic arousal levels and the occurrence or severity of stuttering were found for the intervals prior, during, and after speech. Measures of autonomic arousal although significantly correlated with disfluency, only accounted for small percentages of the variances of fluency and severity. The results therefore support the hypothesis that autonomic arousal may be a source of disruption to speech motor control processes in stutterers, but it is clear that other factors must contribute to the likelihood of speech fluency breakdowns or the severity of those breakdowns.

Degree

Ph.D.

Advisors

Smith, Purdue University.

Subject Area

Speech therapy

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