The effect of age on speed of lexical access.

The present study concerns the effect of aging on speed of lexical access. Normative word-frequency was manipulated in a lexical decision task with older and younger adults. Three methods of comparing processing time in the lexical access stage across age groups were evaluated: the subtraction method, the analysis of covariance, and the additive-factor method. The adequacy of the subtraction method was questioned because of the difficulty of finding a control task identical to the experimental task in all processing stages except lexical access. The analysis of covariance was considered to be inconclusive in this kind of application because of the correlation between the covariate and the independent variable, age. The additive-factor method appeared to be a viable alternative to these two analyses. Within this framework, the lack of an interaction between the two variables, age and word-frequency, indicates that the factors affected different stages of processing. Since word-frequency has been shown to affect the lexical access stage, the present result was taken to suggest that aging does not affect speed of lexical access.