The effects of age of acquisition and frequency trajectory on object naming: comments on Pérez (2007).

Pérez (2007) reported that objective age of acquisition (AoA) was a major determinant of adult object naming latencies when frequency trajectory and cumulative frequency were included in the same regression analysis. In this comment, we discuss several issues concerning the influence of frequency trajectory and AoA and argue that objective AoA is a behavioural outcome and a natural covariate of frequency trajectory. Bonin, Barry, Méot, and Chalard (2004) argued that the critical test of age-limited learning effects is finding an effect of frequency trajectory when AoA was not included as a factor. This critical test was lacking in Pérez's (2007) study, but several re-analyses of his data show that frequency trajectory is a reliable predictor of naming speed when objective AoA is not included in the regression. We conclude that frequency trajectory remains an important independent variable for the study of the effects of age-limited learning.