The effects of age of acquisition on object perception

The age at which an item is acquired has been shown to affect naming latency of words, objects, and faces. The phonological completeness hypothesis situates the effects of age of acquisition (AoA) at speech output. Ellis and Lambon Ralph (2000) argue that the effects of age of acquisition result from a “mapping” between representations of orthography to phonology. However, neither “phonological completeness” nor “mapping” of phonological representations can account for the effects of age of acquisition on familiarity decisions to celebrities' faces and names (Moore & Valentine, 1999). This is because a familiarity decision requires a push button response rather than a verbal response. Moore and Valentine argued that exposure to new exemplars of information peg out the parameters of recognition for that type of information that will facilitate subsequent learning. Thus, the prediction is derived that age of acquisition will affect other perceptual classifications of any familiar stimulus class. We report two object classification experiments, where participants were required to decide whether the pictures of objects, presented at brief exposures, were real or not real. Age of acquisition and word frequency were manipulated in separate experiments. An advantage for early acquired objects was observed, which we argue, cannot be attributable to an effect of word frequency. We further argue, that a phonological locus alone cannot account for the advantage for early acquired objects in this classification task. The results are discussed in terms of additional multiple perceptual input loci as proposed by the Moore and Valentine (1999) set up of a specialised processing system hypothesis (SSPS).