Age and age of acquisition: An evaluation of the cumulative frequency hypothesis

An important determinant of picture and word naming speed is the age at which the names were learned (age of acquisition). Two related 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 less apparent in older than younger adults. Two experiments are reported in which younger and older adults read words varying in age of acquisition or frequency, or named objects varying in age of acquisition. There was an observed effect of word frequency only for young adults' word naming. In contrast, strong age of acquisition effects were found for both the young and the old participants. The implications of these results for theories of how age of acquisition might affect lexical processing are discussed.