Beneficial effects of the mother's voice on infants’ novel word learning

Toddlers' prior social experience with speakers influences their word learning

Toddlers prefer to learn from familiar adults, particularly their caregivers, and perform better on word learning tasks when taught by caregivers than by strangers. However, it remains unclear why toddlers learn better from caregivers than from strangers. One possibility is that toddlers are more receptive to learning from individuals whom they have found to be engaging in previous interactions. The current study tested whether toddlers learn more from an unfamiliar adult who was previously engaging than from an unfamiliar adult who was previously unengaging. Toddlers (27-29 months, N = 40) were taught labels for novel objects by two different experimenters. Prior to word learning, toddlers watched pre-recorded videos of one experimenter utilizing engaging behaviors (i.e., using infant-directed speech, gestures, eye contact, and positive affect) and one experimenter utilizing unengaging behaviors (i.e., using adult-directed speech, no gestures, no eye contact, and neutral affect). Both experimenters were equally engaging during labeling. Word learning was then tested using a looking-while-listening paradigm. The results of linear mixed-effects model, cluster-based permutation, and growth curve analyses suggest heightened performance for words that were taught by the experimenter who was previously engaging. These results begin to reveal the kinds of social experiences that promote success in early word learning.

Two-year-olds at elevated risk for ASD can learn novel words from their parents

Children diagnosed with autism spectrum disorder (ASD) often have smaller vocabularies in infancy compared to typically-developing children. To understand whether their smaller vocabularies stem from problems in learning, our study compared a prospective risk sample of 18 elevated risk and 11 lower risk 24-month-olds on current vocabulary size and word learning ability using a paradigm in which parents teach their child words. Results revealed that both groups learned novel words, even though parents indicated that infants at elevated risk of ASD knew fewer words. This suggests that these early compromised vocabularies cannot be solely linked to difficulties in word formations.

Prosodic input and children's word learning in infant- and adult-directed speech

This study examines (1) whether infant-directed speech (IDS) facilitates children's word learning compared to adult-directed speech (ADS); and (2) the link between the prosody of IDS in word-learning contexts and children's word learning from ADS and IDS. Twenty-four Dutch mother-child dyads participated when children were 18 and 24 months old. We collect mothers' ADS and IDS at both ages and test children's word learning from ADS and IDS at 24 months. We find that Dutch 24-month-old children could reliably learn novel words from both ADS and IDS, and IDS had a facilitative effect. In addition, children's word learning from IDS (but not ADS) is predicted by IDS pitch range when mothers introduce unfamiliar words to children at 18 months. Our findings contribute to an understanding of the role of IDS prosody in language development, highlighting both individual differences and contextual differences in IDS prosody.

No Evidence of Robust Noun-Referent Associations in German-Learning 6- to 14-Month-Olds

Work with the looking-while-listening (LWL-) paradigm suggested that 6-month-old English-learning infants associated several labels for common nouns with pictures of their referents: While one distractor picture was present, infants systematically fixated the named target picture. However, recent work revealed constraints of infants' noun comprehension. The age at which these abilities can be obtained appears to relate to the infants' familiarity with the talker, the target language, and word frequency differences in target-distractor pairs. Here, we present further data to this newly established field of research. We tested 42 monolingual German-learning infants aged 6–14 months by means of the LWL-paradigm. Infants saw two pictures side-by-side on a screen, whilst an unfamiliar male talker named one of both. Overall, infants did not fixate the target picture more than the distractor picture. In line with previous results, infants' performance on the task was higher when target and distractor differed within their word frequency—as operationalized by the parental rating of word exposure. Together, our results add further evidence for constraints on early word learning. They point to cross-linguistic differences in early word learning and strengthen the view that infants might use extra-linguistic cues within the stimulus pairing, such as frequency imbalance, to disambiguate between two potential referents.

Social Inference May Guide Early Lexical Learning

We incorporate social reasoning about groups of informants into a model of word learning, and show that the model accounts for infant looking behavior in tasks of both word learning and recognition. Simulation 1 models an experiment where 16-month-old infants saw familiar objects labeled either correctly or incorrectly, by either adults or audio talkers. Simulation 2 reinterprets puzzling data from the Switch task, an audiovisual habituation procedure wherein infants are tested on familiarized associations between novel objects and labels. Eight-month-olds outperform 14-month-olds on the Switch task when required to distinguish labels that are minimal pairs (e.g., “buk” and “puk”), but 14-month-olds' performance is improved by habituation stimuli featuring multiple talkers. Our modeling results support the hypothesis that beliefs about knowledgeability and group membership guide infant looking behavior in both tasks. These results show that social and linguistic development interact in non-trivial ways, and that social categorization findings in developmental psychology could have substantial implications for understanding linguistic development in realistic settings where talkers vary according to observable features correlated with social groupings, including linguistic, ethnic, and gendered groups.