Expectancy and heart rate as predictors of the speech performance of stutterers

Three adult stutterers who displayed a preexperimental pattern of consistent expectation and occurrence of stuttering were studied in a single-subject design. Multiple linear regression analyses led to the conclusion that cognitive (signalled) expectancy was predictive of stuttering for two of the subjects. The third subject evidenced essentially no relationship between signalled expectancy and disfluent performance. For two subjects, neither mean heart rate nor heart rate variability was predictive of speech performance. For the third subject, mean heart rate was predictive but heart rate variability was not. For two subjects, there was essentially no relationship between the measured physiologic variables and cognitive expectancy. However, for the third subject both mean heart rate and heart rate variability were significantly predictive of cognitive expectancy. These results suggest that adult stutterers should not be viewed as a homogeneous group with respect to preutterance activity that is either cognitive or physiologic. The relationship between preutterance heart rate, heart rate variability, and expectancy responses and between these preutterance variables and subsequent stuttering appears to be individualistic.