Simplicity: A cure for overgeneralizations in language acquisition?
Luca Onnis, Matthew Roberts, & Nick Chater
Abstract
A formal model of learning as induction, the simplicity principle (e.g. Chater & Vit‡nyi, 2001) states that the cognitive system seeks the hypothesis that provides the briefest representation of the available data- here the linguistic input to the child. This model allows learning from positive evidence alone in a probabilistic sense, contrasting with GoldŐs (1967) negative theorems. Data gathered from the CHILDES database were used as an approximation of positive input the child receives from adults. We considered linguistic structures that would yield overgeneralization, according to BakerŐs paradox (Baker, 1979). Two simulations incorporating simplicity were run corresponding to two different hypotheses about the grammar: (1) The child assumes that there are no exceptions to the grammar. This hypothesis leads to overgeneralization. (2) The child assumes that some constructions are not allowed. By measuring the cost to encode a structure given its probability P of occurrence as log2(1/P), the second hypothesis was preferred as it lead to a shorter input description and eliminated overgeneralization.
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