COGNITIVE MEDIATION OF ADULT AGE-DIFFERENCES IN LANGUAGE PERFORMANCE

Young (M = 20 years) and old (M = 68 years) adults completed language processing tasks, measures of working memory capacity (backward span a nd the n-back lag task), inhibitory efficiency (Stroop interference), and processing speed (color naming). Regression analyses revealed that each of the resource measures significantly predicted language perfor mance and attenuated variance in language performance that would other wise be attributed to age. When speed variance was entered into the eq uation first, the mediating influence of the inhibition and working me mory measures remained significant. When speed and inhibition differen ces were controlled, the working memory measures could not reliably pr edict language performance. These results suggest that language perfor mance differences may be fundamentally mediated by age differences in processing speed and inhibitory efficiency.