Grammatical Acquisition: Coevolution of Language and the Language Acquisition Device

An account of grammatical acquisition is developed within the parameter-setting framework applied to a generalized categorial grammar (GCG). The GCG is embedded in a default inheritance network yielding a natural partial ordering (reeecting generality) of parameters which determines a partial order for parameter setting. Computational simulation shows that several resulting acquisition procedures are eeective on a grammar / language set expressing major typological distinctions based on constituent order, and deening 70 distinct full languages and over 200 subset languages. The eeects on acquisition of maturational working memory limitations, trigger presentation sequences, parameter update criteria, and diiering initial settings are explored via computational simulation. Computational simulations of populations of language learners / users instantiating the model show: 1) that variant acquisition procedures with diier-ing constraints and biases exert diiering selective pressures on the evolution of language; 2) acquisition procedures will evolve towards more eecient variants in the environment of adaptation. The reciprocal evolution of language acquisition procedures and of language creates a genuinely coevolutionary dynamic , despite the relative speed of linguistic selection for language variants compared to natural selection for variant language acquisition procedures. and two anonymous reviewers for Language kindly gave comments on earlier drafts which helped considerably improve the present one.