Objective versus estimated age of word acquisition: a study of 202 Italian children.

We provide objective data concerning the age of acquisition (AoA) of words from 202 Italian children 34-69 months of age. We investigated picture naming with 80 concrete words belonging to eight semantic categories that are included in a widely used battery for the study of naming and semantic memory. For each word, we calculated three different indices: two directly expressing the age at which a picture was given the correct name by at least 75% of the subjects, and one expressing the overall percentage of our children who were correct in the task. (For the latter index, we provide separate values for boys and girls.). The correlation between objective indices of AoA and adult estimates culled from the literature was not very high. Moreover, objective indices showed low correlations with frequency and familiarity, in contrast to adult ratings. We conclude that adult estimates of AoA present validity problems and should be used with caution. The full set of stimuli is available at www.psychonomic.org/archive.