Mitchell S. Sommers
Dept. of Psych., Washington Univ., St. Louis, MO 63130
Three experiments were conducted within the framework of the Neighborhood Activation Model of spoken word recognition to examine how the structural organization of the mental lexicon may contribute to age-related declines in spoken language processing. According to the model, lexically hard words are items that are phonetically similar to many other high-frequency words and should be identified less accurately than easy words which are phonetically similar to relatively few, low-frequency items. The results of experiment 1 demonstrated that lexical difficulty had differential effects on older and younger listeners. Specifically, relative to young listeners, older adults exhibited significantly poorer identification scores for lexically hard items. Experiment 2 indicated that these age differences in the effects of lexical difficulty were maintained under conditions in which performance for easy words was the same for older and younger listeners. In the third experiment, reducing the resources available for perceptual identification, by changing from single to multiple talkers, produced greater effects of lexical difficulty for older, compared to younger, listeners. Explanations for the results based on diminished cognitive resources and impaired inhibitory control will be discussed. [Work supported by Washington Univ.]