Intersecting Constraints on Label Learning: Effects of Age, Label Properties, and Referential Context

Selectivity in bilingual nonspeech label learning

This research investigates selectivity in word learning for bilingual infants. Previous work demonstrated that bilingual infants show greater openness to non-native language sounds in object labels than monolinguals (Hay et al., 2015; Singh, 2018). It remains unclear whether bilingual openness extends to nonspeech sounds. We presented 14- and 19-month-old bilinguals with object labels consisting of nonspeech tones. Monolinguals recently displayed learning of the same labels at 14 months, but not 19 months (Graf Estes et al., 2018). In contrast, bilinguals failed to learn the labels. We propose that hearing phonological variation across two languages helps bilinguals reject nonspeech word forms.

Actions speak louder than words: Differences in memory flexibility between monolingual and bilingual 18-month-olds

Bilingual infants from 6- to 24-months of age are more likely to generalize, flexibly reproducing actions on novel objects significantly more often than age-matched monolingual infants are. In the current study, we examine whether the addition of novel verbal labels enhances memory generalization in a perceptually complex imitation task. We hypothesized that labels would provide an additional retrieval cue and aid memory generalization for bilingual infants. Specifically, we hypothesized that bilinguals might be more likely than monolinguals to map multiple perceptual features onto a novel label and therefore show enhanced generalization. Eighty-seven 18-month-old monolingual and bilingual infants were randomly assigned to one of two experimental conditions or a baseline control condition. In the experimental conditions, either no label or a novel label was added during demonstration and again at the beginning of the test session. After a 24-hr delay, infants were tested with the same stimulus set to test cued recall and with a perceptually different but functionally equivalent stimulus set to test memory generalization. Bilinguals performed significantly above baseline on both cued recall and memory generalization in both experimental conditions, whereas monolinguals performed significantly above baseline only on cued recall in both experimental conditions. These findings show a difference between monolinguals and bilinguals in memory generalization and suggest that generalization differences between groups may arise from visual perceptual processing rather than linguistic processing. A video abstract of this article can be viewed at https://youtu.be/yXB4pM3fF2k.

Mapping non-native pitch contours to meaning: Perceptual and experiential factors

Infants show interesting patterns of flexibility and constraint early in word learning. Here, we explore perceptual and experiential factors that drive associative learning of labels that differ in pitch contour. Contrary to the salience hypothesis proposed in Experiment 1, English-learning 14-month-olds failed to map acoustically distinctive level and dipping labels to novel referents, even though they discriminated the labels when no potential referents were present. Conversely, infants readily mapped the less distinctive rising and dipping labels. In Experiment 2, we found that the degree of pitch variation in labels also does not account for learning. Instead, English-learning infants only learned if one of the labels had a rising pitch contour. We argue that experience with hearing and/or producing native language prosody may lead infants to initially over-interpret the role rising pitch plays in differentiating words. Together, our findings suggest that multiple factors contribute to whether specific acoustic forms will function as candidate object labels.