Stuttering as operant behavior: effects of the verbal stimuli wrong, right, and tree on the disfluency rates of school-age stutterers and nonstutterers.

This study assessed the effects of the verbally presented stimuli wrong, right, and tree on the frequency of disfluencies during oral reading by 18 school-aged stutterers and 18 matched nonstutterers. No differences were found between the three stimulus words' effect on the disfluency rate of either subject group. Because decreases in the disfluency rates of stutterers were observed during the presentation of all three stimulus words, the data failed to support the operant model. A discussion of theoretical and experimental implications is given.