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Age of acquisition effects in adult lexical processing reflect loss of plasticity in maturing systems: insights from connectionist networks.
Ellis, A.W. & LAMBON RALPH, M.A.
Journal of Experimental Psychology: Learning, Memory and Cognition, 26(5), 1103-1123.
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Early learned words are recognized and produced faster than later learned words. We show that such age of acquisition effects are a natural property of connectionist models trained by backpropagation when patterns are introduced at different points into training and learning of early and late patterns is cumulative and interleaved. Analysis of hidden unit activations indicates the age of acquisition effect reflects a gradual reduction in network plasticity and a consequent failure to differentiate late items as effectively as early ones. Further simulations examine the effects of vocabulary size, learning rate, sparseness of coding, use of a modified learning algorithm, loss of early items, acquisition of very late items, and lesioning the network. The relationship between age of acquisition and word frequency is explored, including analyses how the relative influence of those factors is modulated by introducing weight decay