The acquisition of subordinate nouns as pragmatic inference

Word learning is characterized by a bias for mapping meanings at the “basic” level (‘dog’), as opposed to a subordinate level (‘poodle’; Markman, 1986, 1990; Clark, 1987; Waxman et al., 1991, 1997). The fact that learners nevertheless acquire subordinate nouns has been attributed to properties of the referential world across multiple labelling events (e.g., Xu & Tanenbaum, 2007b; Spencer et al., 2011). Here we propose that the acquisition of subordinate-level meanings requires pragmatic reasoning that allows learners to take informative relevant alternatives into consideration. In support of this hypothesis, in a series of experiments we find that adult learners exploit information about semantic alternatives to generalize word meanings beyond the basic level. In Experiment 1, the introduction of a labelled alternative at the subordinate level eliminated the basic-level bias. In Experiment 2, this effect was found to be specific to labelled but not unlabeled alternatives. In Experiment 3, the availability of alternatives affected conjectures about subordinate-level word meanings even when these alternatives were presented well after the initial moment of ostensive labeling. Lastly, Experiment 4 replicated the semantic contrast effect using exclusively novel language input, highlighting the general communicative nature of these inferences. We conclude that the acquisition of subordinate nouns relies on pragmatic inferences about the informativity of labels as intentional linguistic-pragmatic acts, as opposed to simple word-to-world co-occurrences.