Young children's developing sensitivity to discourse continuity as a cue to reference

Young children’s developing sensitivity to discourse continuity as a cue to reference Alexandra C. Horowitz Michael C. Frank ahorowit@stanford.edu Department of Psychology Stanford University mcfrank@stanford.edu Department of Psychology Stanford University Abstract A large body of research has been devoted to children’s ability to map names to inferred referents through disam- biguation of a single new item and label. In the presence of a known item and an unknown item, children map a novel label to the novel item rather than the already-named item (Markman & Wachtel, 1988; Merriman, Bowman, & MacWhinney, 1989; Mervis & Bertrand, 1994; Clark, 1990). Though the mechanisms at play are debated, this finding es- tablishes that children can make inferences about a speaker’s likely intended meaning in constrained contexts. While em- ploying their repertoire of word-object mappings may allow children to disambiguate some novel referents, there may be other situations in which multiple items are unknown. Children can also use social-pragmatic cues to infer novel word reference. By age 2, children map novel labels to novel objects that the speaker attends to rather than what they them- selves may be attending to (Baldwin, 1991), and even after a time delay (Baldwin, 1993). Young children apply new terms to the target but not non-target items of a speaker’s search (Tomasello & Barton, 1994), show evidence of consid- ering not only their own novelty perspective, but also what is novel to a speaker in a discourse context (Akhtar, Carpenter, & Tomasello, 1996), and can recognize that speaker naming events may convey social-pragmatic implications about infor- mation that is expected to be shared (Diesendruck & Shemer, Despite this body of evidence on general pragmatic cues, few studies have investigated children’s sensitivity to dis- course structure. Nevertheless, some work suggests that dis- course continuity may provide important opportunities for learning. Frank, Fernald, and Tenenbaum (2013) examined a video corpus of caregivers interacting with their 6–18 month- old children. In these natural settings, they found discourse continuity (that utterances in close succession are likely to relate to the same topic) was as reliably linked to reference as were social cues such as pointing and gaze (Frank, Tenen- baum, & Fernald, 2013). Although this result suggests that discourse continuity may be an available cue to disambiguate reference in the presence of competitors, their work did not provide evidence that learners actually make use of this infor- mation. Therefore, our present studies provide the first test of whether discourse position can be used to determine refer- ence in word learning. We discuss two experiments indicating that both children and adults can use discourse position to resolve reference am- biguity. Additionally, our control condition shows that chil- dren and adults rely on the informativeness of discourse struc- ture rather than simpler heuristics such as temporal proxim- Children can learn new words in pedagogical contexts, but they may also infer reference using a variety of other information sources. Here we investigate children’s sensitivity to the place- ment of novel labels within discourse structure as a possible mechanism for word learning. In Experiment 1, children ages 2–6 years participated in word learning trials featuring two novel items and one novel label. In critical trials, the labels were embedded between two sentences about the same item, whereas in a control condition, the label was introduced after two sentences about the item. Children of all ages were more likely to attribute the label to the toy whose descriptions brack- eted the embedded label, and response strength increased with age. Children across all ages responded at chance in the control condition. In Experiment 2, adults showed the same patterns of responses as children in both critical and control conditions. Together, these results suggest that discourse continuity is a reliable cue to reference for both children and adults. Keywords: word learning; discourse; social cues; language de- velopment. Introduction Children use a variety of strategies for learning new words. In overtly pedagogical situations, children can use cues such as pointing, joint attention, and labeling to establish a direct mapping between an object and name. However, many situa- tions do not feature ostensive labeling events. In these cases, children must rely on other strategies to infer the referent of a novel word. One source of information may come from dis- course structure (the order of utterances and how they relate to each other). Recognizing how speakers relate topic infor- mation may help children resolve reference that would other- wise be ambiguous in the absence of the broader context. For example, a child may not have an idea of what chin- chilla means from an utterance such as, “I love chinchillas!”, but she may apply her knowledge of discourse structure to infer its meaning when the same utterance is related to topi- cal information, such as “I got a new pet. I love chinchillas! They’re so soft.” Children are exposed to information about discourse structure whenever they hear speech, and their ac- cumulation of experience may help them to update and refine their expectations about topic relationships. This developing expertise may allow children to infer meaning that is locally ambiguous, yet resolvable in the context of broader discourse. Little work has explored whether children use discourse structure to scaffold reference disambiguation. Our aim is to address this question by investigating children’s and adults’ recognition of communicative structure when dissoci- ated from other social and ostensive cues. Understanding the contribution of discourse knowledge in children’s reference disambiguation may help identify opportunities for children to infer meaning from topic coherence.