The influence of task presentation and information load on the adaptation effect in stutterers and normal speakers.

Fourteen stutterers and 14 normal speakers read two passages differing in information value under two different conditions. Condition I provided subjects with a priori knowledge regarding the experimental limits and requirements. Condition II withheld such knowledge. Results indicate that adaptation curves for both stutterers and normal speakers were influenced by the information value of the reading passage. Less adaptation was observed with the high information than with the low information passage. The task presentation variable differentiated stutterers from normal speakers. When a priori instructions were provided to stutterers, the adaptation curve assumed a smooth, decelerating course. When a priori instructions were withheld, the curve deviated from the expected course. For normal speakers, identical adaptation trends were observed whether or not a priori instructions were provided. Stuttering adaptation is a function of both linguistic and situational variables; normal nonfluency adaptation is primarily a function of linguistic variables. Theoretical, experimental, and clinical implications are offered.