The varying effects of age of acquisition

There are a number of theories that suggest that age of acquisition (AoA) effects are not uniform across different tasks. Catling and Johnston (2006a) found greater AoA effects within an object-naming task than in a semantic classification task. They explained these findings by suggesting that AoA effects might accumulate according to how many levels of representation a task necessitates access to. Brysbaert and Ghyselinck (2006) explain the difference in AoA effects by proposing two distinct types of AoA (frequency dependent and frequency independent), the first accounted for by a connectionist-type mechanism and the latter situated at the interface between semantics and word production. Moreover, Moore, Smith-Spark, and Valentine (2004) and Holmes and Ellis (2006) have suggested that there are two loci of AoA effects: at the phonological level and somewhere within the perceptual level of representation. Again, this could account for the varying degrees of AoA effects. This study sets about testing these ideas by assessing the effect size of AoA across a series of different tasks that necessitate access to various levels of representation. Experiments 1-4 demonstrate significant effects of AoA in a novel picture-picture verification task, an object classification task, a picture verification task, and an object-naming task. Experiment 5 showed no effects of initial phoneme on the naming of the critical objects used within Experiments 1-4. The implication of the varying AoA effect sizes found within Experiments 1-4 in relation to explanations of AoA are discussed.