Frequency Trajectory Gives Rise to an Age-Limited Learning Effect as a Function of Input-Output Mapping in Connectionist Networks


According to the age of acquisition (AoA) hypothesis, words acquired early in life are processed faster and more accurately than words acquired later (see Juhasz, 2005; Johnston & Barry, 2006 for reviews). Connectionist models have begun to explore the influence of the age/order of acquisition of the items (and also their frequency of encounter) (Ellis & Lambon Ralph, 2000; Lambon Ralph & Ehsan, 2006; Zevin & Seidenberg, 2002). We explored age-limited learning effects in a connectionist model similar to that used by Lambon Ralph and Ehsan (2006) but with the use of a frequency trajectory (Zevin & Seidenberg, 2002), which refers to changes in the frequency of the words over long periods of age, since frequency trajectory is thought to better index age-limited learning effects than traditional AoA measures (Bonin, Barry, Méot, & Chalard, 2004). Our simulations show that the influence of frequency trajectory varies as a function of the mappings between input and output units in a similar type of neural network to that used by Lambon Ralph and Ehsan (2006).

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