Stuttering, emotions, and heart rate during anticipatory anxiety: a critical review

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Abstract

Persons who stutter often report their stuttering is influenced by emotional reactions, yet the nature of such relation is still unclear. Psychophysiological studies of stuttering have failed to find any major association between stuttering and the activity of the sympathetic nervous system. A review of published studies of heart rate in relation to stressful speech situations indicate that adults who stutter tend to show a paradoxical reduction of heart rate compared with nonstuttering persons. Reduction of heart rate has also been observed in humans and mammals during anticipation of an unpleasant stimulus, and is proposed to be an indication of anticipatory anxiety resulting in a “freezing response” with parasympathetic inhibition of the heart rate. It is suggested that speech-related anticipatory anxiety in persons who stutter is likely to be a secondary, conditioned reaction based on previous experiences of stuttering.

Educational objectives: The reader will be able to: (1) describe how the autonomic nervous system is modulated by emotional responses; (2) explain how anticipatory fear often results in inhibition of heart rate due to parasympathetic activation; (3) discuss why emotional reactions in persons who stutter may be secondary to negative experiences of speech problems.

Section snippets

The autonomic nervous system

The ANS controls the visceral functions of the body, such as the contractions of the heart, constriction of blood vessels, blood pressure, digestion, and sweating. The ANS consists of two major subdivisions, the sympathetic and the parasympathetic systems, which cooperate to adapt the bodily functions to different situations and demands (Guyton & Hall, 1996). In many autonomic functions, but not all, the sympathetic and parasympathetic systems have opposite effects, like acceleration versus

The freezing response: biological background

From an evolutionary perspective emotions can be seen as sets of genetically determined responses which are important to solve specific problems, like avoiding danger, finding food and reproducing. Each emotional state is associated with a specific way of reacting and behaving and the nervous system adapts the organism to the demands of the current situation. Both animals and humans show two contrasting behavioral expressions of fear. One is to freeze and become mute, and the other is to become

Autonomic activity in persons who stutter

Two of the most thorough studies of autonomic reactions in persons who stutter were made by Peters and Hulstijn (1984) and Weber and Smith (1990). Peters and Hulstijn measured skin conductance, pulse volume, and heart rate in 24 persons who stuttered and in 24 persons without speech problems. The measurements were taken before, during, and after tasks like mirror writing, intelligence test, reading aloud, and spontaneous speech. Contrary to what may have been expected, the stuttering group did

Alternative explanations of reduced heart rate?

As mentioned above, Obrist et al. (1965) observed reduction of heart rate and increase of vagal activation during anticipation of conditioned unpleasant stimuli. Obrist et al. discussed how this observation could be interpreted, with the basic assumption that vagal responses are not related to emotions like anxiety. Suggested mechanisms like “conditioned pressor response”, respiratory changes, or “orienting response” were found not to be congruent with the observations.

In persons who stutter it

Discussion

The reviewed psychophysiological studies of stuttering suggest that many adults who stutter tend to react with anticipatory anxiety and autonomic coactivation in stressful speech situations. This type of autonomic reaction is characteristic of a freezing response, which implies some degree of inhibition of motor activity and vocalisation. As mentioned above, a possible relation between the freezing response and stuttering was suggested by Peters and Guitar (1991). They proposed that observed

Acknowledgments

This article has been supported by grants from the Swedish Council for Research in the Humanities and Social Sciences, the Crafoord Foundation, and the Royal Physiographic Society. I wish to thank Jarl Risberg for valuable advice and review of manuscript, Charles Beck, University of Alberta, who was instructor for a paper that was the starting point for this article, Björn Folkow, Gothenburg University, for information regarding the physiology of freezing, Deborah Kully, University of Alberta,

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