On the source of children’s conjunctive interpretation of disjunction: Scope, strengthening, or both?

ABSTRACT In a body of empirical research, it has been observed that young children from across different linguistic communities adhered to a particular type of nonadult interpretation of disjunction: They appear to interpret disjunction conjunctively. Through three experiments with Japanese-speaking preschoolers, we investigate the source of this nonadult behavior. Specifically, we ask whether children’s conjunctive interpretation of disjunction in negative sentences can be reduced to strengthening via implicature. To test this possibility, we presented Japanese children with test sentences in which the crucial disjunctive NP was located in different syntactic positions: accusative-marked object (Experiment 1), nominative-marked subject (Experiment 2), and nominative-marked object (Experiment 3). The results showed that children systematically altered their interpretations of disjunction according to its syntactic position in the test sentence. Importantly, they consistently accepted adultlike disjunctive interpretations of the test sentences in Experiments 2 and 3, but they showed adherence to the conjunctive interpretation in Experiment 1. These behaviors cannot be explained by the strengthening account, suggesting that children’s conjunctive interpretation of disjunction in negative sentences is due to their nonadult scope assignment.