Publications (3)6.32 Total impact
Article: When global structure "Explains Away" local grammar: a Bayesian account of rule-induction in tone sequences.[show abstract] [hide abstract]
ABSTRACT: While many constraints on learning must be relatively experience-independent, past experience provides a rich source of guidance for subsequent learning. Discovering structure in some domain can inform a learner's future hypotheses about that domain. If a general property accounts for particular sub-patterns, a rational learner should not stipulate separate explanations for each detail without additional evidence, as the general structure has "explained away" the original evidence. In a grammar-learning experiment using tone sequences, manipulating learners' prior exposure to a tone environment affects their sensitivity to the grammar-defining feature, in this case consecutive repeated tones. Grammar-learning performance is worse if context melodies are "smooth" -- when small intervals occur more than large ones -- as Smoothness is a general property accounting for a high rate of repetition. We present an idealized Bayesian model as a "best case" benchmark for learning repetition grammars. When context melodies are Smooth, the model places greater weight on the small-interval constraint, and does not learn the repetition rule as well as when context melodies are not Smooth, paralleling the human learners. These findings support an account of abstract grammar-induction in which learners rationally assess the statistical evidence for underlying structure based on a generative model of the environment.Cognition 01/2011; 120(3):350-9. · 3.16 Impact Factor
Article: From domain-generality to domain-sensitivity: 4-month-olds learn an abstract repetition rule in music that 7-month-olds do not.[show abstract] [hide abstract]
ABSTRACT: Learning must be constrained for it to lead to productive generalizations. Although biology is undoubtedly an important source of constraints, prior experience may be another, leading learners to represent input in ways that are more conducive to some generalizations than others, and/or to up- and down-weight features when entertaining generalizations. In two experiments, 4-month-old and 7-month-old infants were familiarized with sequences of musical chords or tones adhering either to an AAB pattern or an ABA pattern. In both cases, the 4-month-olds learned the generalization, but the 7-month-olds did not. The success of the 4-month-olds appears to contradict an account that this type of pattern learning is the provenance of a language-specific rule-learning module. It is not yet clear what drives the age-related change, but plausible candidates include differential experience with language and music, as well as interactions between general cognitive development and stimulus complexity.Cognition 04/2009; 111(3):378-82. · 3.16 Impact Factor
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ABSTRACT: The recent language acquisition literature has revealed powerful, domain-general learning mechanisms that rely on frequency and distributional properties of the input. A second set of research investigates generalization of learned patterns to new input. The relationship between these two bodies is not entirely clear. The present paper demonstrates that the latter mechanism appears to be domain-general as well, although, in the domain of musical chord sequences, there is a decrease in sensitivity to algebraic patterns between 4 months of age and 7.5 months of age. We show that 4-month-old infants can discriminate three-chord patterns based on their AAB or ABA structure after being exposed to a set of patterns representing one of the structures. By 7.5 months, however, infants do not seem to make the discrimination, probably due to their experience with musical sequences, in which repetition plays less of a role than tonal structure.