Navigating accent variability: 24-month-olds recognize known words spoken in an unfamiliar accent but require additional support to learn new words.

As infants learn their native languages, they must also learn to contend with variability across speakers of those languages. Here, we examine 24-month-olds' ability to process speech in an unfamiliar accent. We demonstrate that 24-month-olds successfully identify the referents of known words in unfamiliar-accented speech but cannot use known words alone to infer new word meanings. However, when the novel word occurs in a supportive referential context, with the target referent visually available, 24-month-olds successfully learn new word-referent mappings. Thus, 24-month-olds recognize and learn words in unfamiliar accents, but unfamiliar-accented speech may pose challenges for more sophisticated language processing strategies.

Preschoolers benefit from sentential context in familiar- and unfamiliar-accented speech.

To learn the meaning of a new word, or to recognize the meaning of a known one, both children and adults benefit from surrounding words, or the sentential context. Most of the evidence from children is based on their accuracy and efficiency when listening to speech in their familiar native accent: they successfully use the words they know to identify other words' referents. Here, we assess how accurately and efficiently 4-year-old children use sentential context to identify referents of known and novel nouns in unfamiliar-accented speech, as compared to familiar-accented speech. In a looking-while-listening task, children showed considerable success in processing unfamiliar-accented speech. Children robustly mapped known nouns produced in an unfamiliar accent to their target referents rather than novel competitors, and they used informative surrounding verbs (e.g., "You can eat the dax") to identify the referents of both known and novel nouns-although there was a processing cost for unfamiliar-accented speech in some cases. This demonstrates that 4-year-olds successfully and rapidly process unfamiliar-accented speech by recruiting the same strategies available to them in familiar-accented speech, revealing impressive flexibility in word recognition and word learning across diverse linguistic environments. RESEARCH HIGHLIGHTS: We examined 4-year-old children's accuracy and processing efficiency in comprehending known and novel nouns embedded in sentences produced in familiar-accented or unfamiliar-accented speech. Children showed limited processing costs for unfamiliar-accented speech and mapped known words to their referents even when these were produced in unfamiliar-accented speech. Children used known verbs to predict the referents of upcoming nouns in both familiar- and unfamiliar-accented speech, but processing costs were evident for unfamiliar-accented speech. Thus, the strategies that support children's word comprehension and word learning in familiar-accented speech are available to them in unfamiliar accents as well.

How pervasive is joint attention? Mother-child dyads from a Wichi community reveal a different form of "togetherness".

Theories of early development have emphasized the power of caregivers as active agents in infant socialization and learning. However, there is variability, across communities, in the tendency of caregivers to engage with their infants directly. This raises the possibility that infants and children in some communities spend more time engaged in solitary activities than in dyadic or triadic interactions. Here, we focus on one such community (indigenous Wichi living in Argentina's Chaco Forest) to test this possibility. We examine naturally occurring attentional activity involving the mother and child among the Wichi and among Eurodescendant Spanish-speaking families living in Argentina. We engaged 16 families-8 Wichi and 8 Eurodescendant-in an observational study of interactions between caregivers and their 1- to 2-year-olds. A mixed-analytic approach revealed no differences between communities in the proportion of time infants spent alone, or in mother-child interaction. What does differ, however, is how mothers engage in these interactions: Wichi mothers spend a greater proportion of their time observing their infants than do Eurodescendant mothers. Moreover, when infants in both groups are alone, they focus their 'solitary' activities differently: Wichi infants engaged primarily in observation alone, whereas Eurodescendant infants were more focused on the object. Finally, all mother-child pairs engaged in dyadic and triadic (object-infant-caregiver) patterns of attention, but the triadic patterns differed considerably between cultures: Among Wichi, mothers actively "watched" infants as they engaged with objects, whereas Eurodescendant mothers actively engaged with their infants in joint attentional episodes. This work illustrates how attention and socialization, key mechanisms of early development, are culturally organized. A video abstract of this article can be viewed at https://www.youtube.com/watch?v=SwsOCLXubKQ. RESEARCH HIGHLIGHTS: Longitudinal, observational investigation of mother-infant interaction in two distinct Argentine cultural groups (Wichi and Eurodescendants) reveals both commonalities and clear community-based differences in interactions between mothers and their 1- to 2-year-olds. Wichi mother-infant dyads engaged primarily in visual observation of one another, but their Eurodescendant counterparts tended to engage in more verbal or physical interaction. We identify a new form of triadic interaction-lateral joint attention-among the Wichi dyads. This work underscores that attention and socialization, key mechanisms of early development, are culturally organized.

A principled link between object naming and representation is available to infants by seven months of age.

By their first birthdays, infants represent objects flexibly as a function of not only whether but how the objects are named. Applying the same name to a set of different objects from the same category supports object categorization, with infants encoding commonalities among objects at the expense of individuating details. In contrast, applying a distinct name to each object supports individuation, with infants encoding distinct features at the expense of categorical information. Here, we consider the development of this nuanced link between naming and representation in infants' first year. Infants at 12 months (Study 1; N = 55) and 7 months (Study 2; N = 96) participated in an online recognition memory task. All infants saw the same objects, but their recognition of these objects at test varied as a function of how they had been named. At both ages, infants successfully recognized objects that had been named with distinct labels but failed to recognize these objects when they had all been named with the same, consistent label. This new evidence demonstrates that a principled link between object naming and representation is available by 7 months, early enough to support infants as they begin mapping words to meaning.

Talking About the Absent and the Abstract: Referential Communication in Language and Gesture.

Human language permits us to call to mind objects, events, and ideas that we cannot witness directly, either because they are absent or because they have no physical form (e.g., people we have not met, concepts like justice). What enables language to transmit such knowledge? We propose that a referential link between words, referents, and mental representations of those referents is key. This link enables us to form, access, and modify mental representations even when the referents themselves are absent ("absent reference"). In this review we consider the developmental and evolutionary origins of absent reference, integrating previously disparate literatures on absent reference in language and gesture in very young humans and gesture in nonhuman primates. We first evaluate when and how infants acquire absent reference during the process of language acquisition. With this as a foundation, we consider the evidence for absent reference in gesture in infants and in nonhuman primates. Finally, having woven these literatures together, we highlight new lines of research that promise to sharpen our understanding of the development of reference and its role in learning about the absent and the abstract.

Longer looks for language: Novel labels lengthen fixation duration for 2-year-old children.

The language infants hear guides their visual attention; infants look more to objects when they are labeled. However, it is unclear whether labels also change the way infants attend to and encode those objects-that is, whether hearing an object label changes infants' online visual processing of that object. Here, we examined this question in the context of novel word learning, asking whether nuanced measures of visual attention, specifically fixation durations, change when 2-year-olds hear a label for a novel object (e.g., "Look at the dax") compared with when they hear a non-labeling phrase (e.g., "Look at that"). Results confirmed that children visually process objects differently when they are labeled, using longer fixations to examine labeled objects versus unlabeled objects. Children also showed robust retention of these labels on a subsequent test trial, suggesting that these longer fixations accompanied successful word learning. Moreover, when children were presented with the same objects again in a silent re-exposure phase, children's fixations were again longer when looking at the previously labeled objects. Finally, fixation duration at first exposure and silent re-exposure were correlated, indicating a persistent effect of language on visual processing. These effects of hearing labels on visual attention point to the critical interactions involved in cross-modal learning and emphasize the benefits of looking beyond aggregate measures of attention to identify cognitive learning mechanisms during infancy.

From Recognizing Known Words to Learning New Ones: Comparing Online Speech Processing in Typically Developing and Late-Talking 2-Year-Olds.

PURPOSE: This study examines online speech processing in typically developing and late-talking 2-year-old children, comparing both groups' word recognition, word prediction, and word learning. METHOD: English-acquiring U.S. children, from the "When to Worry" study of language and social-emotional development, were identified as typical talkers (n = 67, M age = 27.0 months, SD = 1.4; Study 1) or late talkers (n = 30, M age = 27.0 months, SD = 2.0; Study 2). Children completed an eye-tracking task assessing their ability to recognize both nouns and verbs, to use verbs to predict an upcoming noun's referent, and to use verbs to infer the meaning of novel nouns. RESULTS: Both typical and late talkers recognized nouns and verbs and used familiar verbs to predict the referents of upcoming nouns, whether the noun was familiar ("You can eat the apple") or novel ("You can eat the dax"). Late talkers were slower in using familiar nouns to orient to the target and were both slower and less accurate in using familiar verbs to identify the upcoming noun's referent. Notably, however, both groups learned and retained novel word meanings with similar success. CONCLUSIONS: Late talkers demonstrated slower lexical processing, especially for verbs. Yet, their success in using familiar verbs to learn novel nouns suggests that, as a group, their slower processing did not impair word learning in this task. This sets the foundation for future work investigating whether these measures predict later language outcomes and can differentiate late talkers with transient delays from those with language disorders.

I See What You Are Saying: Hearing Infants' Visual Attention and Social Engagement in Response to Spoken and Sign Language.

Infants are endowed with a proclivity to acquire language, whether it is presented in the auditory or visual modality. Moreover, in the first months of life, listening to language supports fundamental cognitive capacities, including infants' facility to form object categories (e.g., dogs and bottles). Recently, we have found that for English-acquiring infants as young as 4 months of age, this precocious interface between language and cognition is sufficiently broad to include not only their native spoken language (English), but also sign language (American Sign Language, ASL). In the current study, we take this work one step further, asking how "sign-naïve" infants-hearing infants with no prior exposure to sign language-deploy their attentional and social strategies in the context of episodes involving either spoken or sign language. We adopted a now-standard categorization task, presenting 4- to 6-month-old infants with a series of exemplars from a single category (e.g., dinosaurs). Each exemplar was introduced by a woman who appeared on the screen together with the object. What varied across conditions was whether this woman introduced the exemplar by speaking (English) or signing (ASL). We coded infants' visual attentional strategies and their spontaneous vocalizations during this task. Infants' division of attention and visual switches between the woman and exemplar varied as a function of language modality. In contrast, infants' spontaneous vocalizations revealed similar patterns across languages. These results, which advance our understanding of how infants allocate attentional resources and engage with communicative partners across distinct modalities, have implications for specifying our theories of language acquisition.

Rhythm May Be Key to Linking Language and Cognition in Young Infants: Evidence From Machine Learning.

Rhythm is key to language acquisition. Across languages, rhythmic features highlight fundamental linguistic elements of the sound stream and structural relations among them. A sensitivity to rhythmic features, which begins in utero, is evident at birth. What is less clear is whether rhythm supports infants' earliest links between language and cognition. Prior evidence has documented that for infants as young as 3 and 4 months, listening to their native language (English) supports the core cognitive capacity of object categorization. This precocious link is initially part of a broader template: listening to a non-native language from the same rhythmic class as (e.g., German, but not Cantonese) and to vocalizations of non-human primates (e.g., lemur, Eulemur macaco flavifrons, but not birds e.g., zebra-finches, Taeniopygia guttata) provide English-acquiring infants the same cognitive advantage as does listening to their native language. Here, we implement a machine-learning (ML) approach to ask whether there are acoustic properties, available on the surface of these vocalizations, that permit infants' to identify which vocalizations are candidate links to cognition. We provided the model with a robust sample of vocalizations that, from the vantage point of English-acquiring 4-month-olds, either support object categorization (English, German, lemur vocalizations) or fail to do so (Cantonese, zebra-finch vocalizations). We assess (a) whether supervised ML classification models can distinguish those vocalizations that support cognition from those that do not, and (b) which class(es) of acoustic features (including rhythmic, spectral envelope, and pitch features) best support that classification. Our analysis reveals that principal components derived from rhythm-relevant acoustic features were among the most robust in supporting the classification. Classifications performed using temporal envelope components were also robust. These new findings provide in principle evidence that infants' earliest links between vocalizations and cognition may be subserved by their perceptual sensitivity to rhythmic and spectral elements available on the surface of these vocalizations, and that these may guide infants' identification of candidate links to cognition.

Sparse labels, no problems: Infant categorization under challenging conditions.

Labeling promotes infants' object categorization even when labels are rare. By 2 years, infants engage in "semi-supervised learning" (SSL), integrating labeled and unlabeled exemplars to learn categories. However, everyday learning contexts pose substantial challenges for infants' SSL. Here, two studies (n = 74, 51% female, 62% non-Hispanic White, 18% multiracial, 8% Asian, 6% Black, Mage  = 27.3 months, collected 2018-2020) implemented a familiarization-novelty preference paradigm assessing 2-year-olds' SSL when (i) exemplars from the target category are interspersed with other objects (Study 1, d = .67) and (ii) multiple categories are learned simultaneously (Study 2, d = .74). The findings indicate 2-year-olds' SSL is robust enough to support object categorization despite substantial challenges posed by everyday learning contexts.

Hands on: Nonverbal communication in Native and non-Native American parent-child dyads during informal learning.

Parent-child communication is a rich, multimodal process. Substantial research has documented the communicative strategies in certain (predominantly White) United States families, yet we know little about these communicative strategies in Native American families. The current study addresses that gap by documenting the verbal and nonverbal behaviors used by parents and their 4-year-old children (N = 39, 25 boys) across two communities: Menominee families (low to middle income) living on tribal lands in rural Wisconsin, and non-Native, primarily White families (middle income) living in an urban area. Dyads participated in a free-play forest-diorama task designed to elicit talk and play about the natural world. Children from both communities incorporated actions and gestures freely in their talk, emphasizing the importance of considering nonverbal behaviors when evaluating what children know. In sharp contrast to the stereotype that Native American children talk very little, Menominee children talked more than their non-Native counterparts, underlining the importance of taking into account cultural context in child assessments. For children and parents across both communities, gestures were more likely than actions to be related to the content of speech and were more likely than actions to be produced simultaneously with speech. This tight coupling between speech and gesture replicates and extends prior research with predominantly White (and adult) samples. These findings not only broaden our theories of communicative interaction and development, but also provide new evidence about the role of nonverbal behaviors in informal learning contexts. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Racial Awareness and Bias Begin Early: Developmental Entry Points, Challenges, and a Call to Action.

Overt expressions of racial intolerance have surged precipitously. The dramatic uptick in hate crimes and hate speech is not lost on young children. But how, and how early, do children become aware of racial bias? And when do their own views of themselves and others become infused with racial bias? This article opens with a brief overview of the existing experimental evidence documenting developmental entry points of racial bias in infants and young children and how it unfolds. The article then goes on to identify gaps in the extant research and outlines three steps to narrow them. By bringing together what we know and what remains unknown, the goal is to provide a springboard, motivating a more comprehensive psychological-science framework that illuminates early steps in the acquisition of racial bias. If we are to interrupt race bias at its inception and diminish its effects, then we must build strong cross-disciplinary bridges that span the psychological and related social sciences to shed light on the pressing issues facing our nation's young children and their families.

Acquiring verbal reference: The interplay of cognitive, linguistic, and general learning capacities.

Verbal reference is the ability to use language to communicate about objects, events, or ideas, even if they are not witnessed directly, such as past events or faraway places. It rests on a three-way link between words, their referents, and mental representations of those referents. A foundational human capacity, verbal reference extends the communicative power of language beyond the here-and-now, enabling access to language-mediated learning and thus fueling cognitive development. In the current review, we consider how and when verbal reference develops. The existing literature suggests that verbal reference emerges around infants' first birthdays and becomes increasingly robust by their second. In discussing the powerful developmental advantages of acquiring verbal reference we propose that this achievement requires a dynamic interplay among infants' cognitive and language development, fueled by general learning capacities. We close by describing new research directions, aimed at advancing our understanding of how verbal reference emerges.

Sign language, like spoken language, promotes object categorization in young hearing infants.

The link between language and cognition is unique to our species and emerges early in infancy. Here, we provide the first evidence that this precocious language-cognition link is not limited to spoken language, but is instead sufficiently broad to include sign language, a language presented in the visual modality. Four- to six-month-old hearing infants, never before exposed to sign language, were familiarized to a series of category exemplars, each presented by a woman who either signed in American Sign Language (ASL) while pointing and gazing toward the objects, or pointed and gazed without language (control). At test, infants viewed two images: one, a new member of the now-familiar category; and the other, a member of an entirely new category. Four-month-old infants who observed ASL distinguished between the two test objects, indicating that they had successfully formed the object category; they were as successful as age-mates who listened to their native (spoken) language. Moreover, it was specifically the linguistic elements of sign language that drove this facilitative effect: infants in the control condition, who observed the woman only pointing and gazing failed to form object categories. Finally, the cognitive advantages of observing ASL quickly narrow in hearing infants: by 5- to 6-months, watching ASL no longer supports categorization, although listening to their native spoken language continues to do so. Together, these findings illuminate the breadth of infants' early link between language and cognition and offer insight into how it unfolds.

An object lesson: Objects, non-objects, and the power of conceptual construal in adjective extension.

Despite the seemingly simple mapping between adjectives and perceptual properties (e.g., color, texture), preschool children have difficulty establishing the appropriate extension of novel adjectives. When children hear a novel adjective applied to an individual object, they successfully extend the adjective to other members of the same object category but have difficulty extending it more broadly to members of different categories. We propose that the source of this difficulty lies at the interface of the linguistic and conceptual systems: children initially limit the extension of an adjective to the category of the object on which it was introduced. To test this hypothesis, we manipulated whether participants construed images as "pictures of things" (objects) or "blobs of stuff" (non-objects). For both 36-month-old children (Experiments 1 and 2) and adults (Experiment 3), the conceptual status of an image influenced how they extended an adjective applied to that image. Children extended novel adjectives more successfully when they construed the images as non-objects than when they construed the same images as objects. Similarly, adults were faster to make adjective extensions when construing the images as non-objects rather than objects. Learners of all ages must navigate this linguistic-conceptual interface in assessing whether and how novel adjectives should be extended to new individuals.

Developmental changes in auditory-evoked neural activity underlie infants' links between language and cognition.

The power and precision with which humans link language to cognition is unique to our species. By 3-4 months of age, infants have already established this link: simply listening to human language facilitates infants' success in fundamental cognitive processes. Initially, this link to cognition is also engaged by a broader set of acoustic stimuli, including non-human primate vocalizations (but not other sounds, like backwards speech). But by 6 months, non-human primate vocalizations no longer confer this cognitive advantage that persists for speech. What remains unknown is the mechanism by which these sounds influence infant cognition, and how this initially broader set of privileged sounds narrows to only human speech between 4 and 6 months. Here, we recorded 4- and 6-month-olds' EEG responses to acoustic stimuli whose behavioral effects on infant object categorization have been previously established: infant-directed speech, backwards speech, and non-human primate vocalizations. We document that by 6 months, infants' 4-9 Hz neural activity is modulated in response to infant-directed speech and non-human primate vocalizations (the two stimuli that initially support categorization), but that 4-9 Hz neural activity is not modulated at either age by backward speech (an acoustic stimulus that doesn't support categorization at either age). These results advance the prior behavioral evidence to suggest that by 6 months, speech and non-human primate vocalizations elicit distinct changes in infants' cognitive state, influencing performance on foundational cognitive tasks such as object categorization.

Birdsong fails to support object categorization in human infants.

Recent evidence reveals a precocious link between language and cognition in human infants: listening to their native language supports infants' core cognitive processes, including object categorization, and does so in a way that other acoustic signals (e.g., time-reversed speech; sine-wave tone sequences) do not. Moreover, language is not the only signal that confers this cognitive advantage: listening to vocalizations of non-human primates also supports object categorization in 3- and 4-month-olds. Here, we move beyond primate vocalizations to clarify the breadth of acoustic signals that promote infant cognition. We ask whether listening to birdsong, another naturally produced animal vocalization, also supports object categorization in 3- and 4-month-old infants. We report that listening to zebra finch song failed to confer a cognitive advantage. This outcome brings us closer to identifying a boundary condition on the range of non-linguistic acoustic signals that initially support infant cognition.

Semantic priming supports infants' ability to learn names of unseen objects.

Human language permits us to call to mind objects, events, and ideas that we cannot witness directly. This capacity rests upon abstract verbal reference: the appreciation that words are linked to mental representations that can be established, retrieved and modified, even when the entities to which a word refers is perceptually unavailable. Although establishing verbal reference is a pivotal achievement, questions concerning its developmental origins remain. To address this gap, we investigate infants' ability to establish a representation of an object, hidden from view, from language input alone. In two experiments, 15-month-olds (N = 72) and 12-month-olds (N = 72) watch as an actor names three familiar, visible objects; she then provides a novel name for a fourth, hidden fully from infants' view. In the Semantic Priming condition, the visible familiar objects all belong to the same semantic neighborhood (e.g., apple, banana, orange). In the No Priming condition, the objects are drawn from different semantic neighborhoods (e.g., apple, shoe, car). At test infants view two objects. If infants can use the naming information alone to identify the likely referent, then infants in the Semantic Priming, but not in the No Priming condition, will successfully infer the referent of the fourth (hidden) object. Brief summary of results here. Implications for the development of abstract verbal reference will be discussed.

Does Human Touch Facilitate Object Categorization in 6-to-9-Month-Old Infants?

Infants form object categories in the first months of life. By 3 months and throughout the first year, successful categorization varies as a function of the acoustic information presented in conjunction with category members. Here we ask whether tactile information, delivered in conjunction with category members, also promotes categorization. Six- to 9-month-olds participated in an object categorization task in either a touch-cue or no-cue condition. For infants in the touch-cue condition, familiarization images were accompanied by precisely-timed light touches from their caregivers; infants in the no-cue condition saw the same images but received no touches. Only infants in the touch-cue condition formed categories. This provides the first evidence that touch may play a role in supporting infants' object categorization.

Naming guides how 12-month-old infants encode and remember objects.

A foundation of human cognition is the flexibility with which we can represent any object as either a unique individual (my dog Fred) or a member of an object category (dog, animal). This conceptual flexibility is supported by language; the way we name an object is instrumental to our construal of that object as an individual or a category member. Evidence from a new recognition memory task reveals that infants are sensitive to this principled link between naming and object representation by age 12 mo. During training, all infants (n = 77) viewed four distinct objects from the same object category, each introduced in conjunction with either the same novel noun (Consistent Name condition), a distinct novel noun for each object (Distinct Names condition), or the same sine-wave tone sequence (Consistent Tone condition). At test, infants saw each training object again, presented in silence along with a new object from the same category. Infants in the Consistent Name condition showed poor recognition memory at test, suggesting that consistently applied names focused them primarily on commonalities among the named objects at the expense of distinctions among them. Infants in the Distinct Names condition recognized three of the four objects, suggesting that applying distinct names enhanced infants' encoding of the distinctions among the objects. Infants in the control Consistent Tone condition recognized only the object they had most recently seen. Thus, even for infants just beginning to speak their first words, the way in which an object is named guides infants' encoding, representation, and memory for that object.