The Influence of Word Frequency and Aging on Lexical Access

Visual word recognition has been a central area of psychological inquiry over the past century. The current dissertation examines how visual word recognition changes as a function of age by focusing on the influence of word frequency, or how commonly a word is encountered. Word frequency is arguably the strongest predictor of visual word recognition performance across a variety of language tasks, and the most influential factor in models of language processing. All models of visual word recognition include a strong role for word frequency but often assume different underlying mechanisms, which produce differing predictions for age changes. Although there is already a literature examining word frequency effects in younger and older adults, these studies have produced inconsistent results, possibly due to procedural limitations and task-specific processes. This dissertation explores the influence of task and age on the word frequency effect, while directly examining individual differences (e.g., changes in vocabulary, vision, education) in order to better understand the mechanisms underlying word frequency effects. In contrast to the dichotomous approach of examining extreme groups of young and older adults, or extreme bands of word frequency, the present study examined both variables in a continuous manner. The primary finding is that the word frequency effect does not appear to change as a function of age across all three tasks considered. This finding is discussed in reference to previous inconsistent findings in the literature and important theoretical implications