ABSTRACT
An important determinant of picture and word naming speed is the age at which the words were learned, that is, their age of acquisition (AoA). Two possible interpretations of these effects are that they reflect differences between words in their cumulative frequency of use, or that they reflect differences in the amount of time early- and late-acquired words have spent in lexical memory. Both theories predict that differences between early- and late-acquired words will be smaller in older than younger adults. We report three experiments in which younger and older adults read words varying in AoA or frequency, or named objects varying in AoA. There was no effect of word frequency when AoA was controlled. In contrast, strong AoA effects which did not diminish with age were found. The implications of these results for theories of how AoA affects lexical processing are discussed.
