말과제와 인지과제 동시수행이 정상성인 및 말더듬성인의 유창성에 미치는 영향

The Effects of Concurrent Performance of Cognitive Tasks and Speech Tasks on Speech Fluency of Individuals who Stutter

본 연구에서는 말더듬성인 9명과 정상성인 10명이 두 종류의 말과제와 세 종류의 인지과제를 각각 혹은 동시에 수행하였을 때 말더듬빈도와 인지과제의 반응시간 및 반응정확도에 어떠한 변화가 나타나는지 살펴보았다. 이야기 말하기에서 정상집단은 이야기만 할때에 비하여 이야기와 인지과제를 동시에 할 때 말더듬빈도가 유의하게 증가하였다. 이는 동시과제 조건에서 인지적 요구(demand)가 증가하였고, 이것이 유창한 말을 유지할 수 있는 능력(capacity)을 초과하여 말더듬빈도가 증가한 것으로 설명할 수 있다. 한편, 말더듬집단은 동일한 조건에서 유의한 차이를 보이지 않았는데, 이는 말더듬집단의 개인차가 컸던 점과 관련될 수 있을 것으로 보인다. 모든 조건의 반응시간 및 반응정확도에서는 유의한 집단간 차이가 나타나지 않아 말더듬집단이 더 유의하게 말에 대한 선택적인 주의를 기울였다고 말하기는 어렵다.

The purpose of the present study was to test whether stutterer s speech disfluencies changed when they concurrently performed 3 kinds of cognitive tasks with different levels of demands- - a detection task, and two discrimination tasks with different number of choices. The effect of the increasing demand on stutterers disfluencies were measured in 2 different speech tasks- - counting which was thought to require minimum resources and story retelling which was thought to resemble our daily life discourse requiring higher demands. Nine adult stutterers and 10 non- stuttering adult s participated in the study. Inconsistent with demand and capacity model of stuttering, stutterer s disfluencies did not increase significantly when the demand increased with concurrent performance cognitive tasks. This result was found regardless of the difficulties of cognitive tasks and the types of speech tasks. Interestingly, concurrent performance of cognitive tasks did significantly increase non- stutterers disfluencies during story- retelling. Because no significant group differences were noted either in RT or in the accuracy of the cognitive tasks, it is not likely that the stutterers kept their speech performance at the cost of cognitive task performance. The examination of stutterer s individual data in story- retelling showed a wide variability among the participant s. Such result s indicated that although non- stutterer s speech fluency is generally affected by the demand of cognitive tasks, there may be substantial individual differences in the stutterer s susceptibility to the increased cognitive demand.