Irrelevant sound disrupts speech production: Exploring the relationship between short-term memory and experimentally induced slips of the tongue

To explore the relationship between short-term memory and speech production, we developed a speech error induction technique. The technique, which was adapted from a Japanese word game, exposed participants to an auditory distractor word immediately before the utterance of a target word. In Experiment 1, the distractor words that were phonologically similar to the target word led to a greater number of errors in speaking the target than did the dissimilar distractor words. Furthermore, the speech error scores were significantly correlated with memory span scores. In Experiment 2, memory span scores were again correlated with the rate of the speech errors that were induced from the task-irrelevant speech sounds. Experiment 3 showed a strong irrelevant-sound effect in the serial recall of nonwords. The magnitude of the irrelevant-sound effects was not affected by phonological similarity between the to-be-remembered nonwords and the irrelevant-sound materials. Analysis of recall errors in Experiment 3 also suggested that there were no essential differences in recall error patterns between the dissimilar and similar irrelevant-sound conditions. Weproposed two different underlying mechanisms in immediate memory, one operating via the phonological short-term memory store and the other via the processes underpinning speech production.