A cinefluorographic investigation of repeated fluent productions of stutterers in an adaptation procedure.

Cinefluorography was used to study three stutterers and two nonstutterers repeating a passage made up of monosyllables. CVC target words of the form/caet/ were embedded in the passage and were analyzed to determine the effects of repeating the passage on velocities, displacements, and durations of movements of the tongue, jaw, and lower lip. Coordination among the articulators was also assessed. The investigation was undertaken to test the hypothesis that decreases in velocities and displacements, increased movement durations, and decreased latency between the onsets of jaw movements and of tongue tip movements would be associated with the repeated readings. The hypothesis was not supported by the results. A post hoc analysis showed that a decrease in the variability of instantaneous velocities (and by inference a decrease in variation in muscle stiffness) was associated with practice for the three stutterers but not for the nonstutterers. Inferences about the adaptation effect are made related (a) to the stabilization of tonic muscle activity which may be associated with a decrease in arousal, and (b) to the effects of practice.