Can a Click be a Word?: Infants' Learning of Non‐Native Words

Forms that are nonlinguistic markers in one language (i.e., “tsk‐tsk” in English) may be part of the phoneme inventory—and hence part of words—in another language. In the current paper, we demonstrate that infants' ability to learn words containing unfamiliar language sounds is influenced by the age and vocabulary size of the infant learner, as well as by cues to the speaker's referential intent. When referential cues were available, infants at 14 months learned words with non‐native speech sounds, but at 20 months only those infants with smaller vocabularies succeeded. When no referential cues were present, infants at both 14 and 20 months failed to learn the same words. The implications of the relation between linguistic sophistication and non‐native word learning are discussed.     

Home Environment,But Not Socioeconomic Status,is Linked to Differences in Early Phonetic Perception Ability

Infants perceptually tune to the phonemes of their native languages in the first year of life, thereby losing the ability to discriminate non‐native phonemes. Infants who perceptually tune earlier have been shown to develop stronger language skills later in childhood. We hypothesized that socioeconomic disparities, which have been associated with differences in the quality and quantity of language in the home, would contribute to individual differences in phonetic discrimination. Seventy‐five infants were assessed on measures of phonetic discrimination at 9 months, on the quality of the home environment at 15 months, and on language abilities at both ages. Phonetic discrimination did not vary according to socioeconomic status (SES), but was significantly associated with the quality of the home environment. This association persisted when controlling for 9‐month expressive language abilities, rendering it less likely that infants with better expressive language skills were simply engendering higher quality home interactions. This suggests that infants from linguistically richer home environments may be more tuned to their native language and therefore less able to discriminate non‐native contrasts at 9 months relative to infants whose home environments are less responsive. These findings indicate that home language environments may be more critical than SES in contributing to early language perception, with possible implications for language development more broadly.     

The Ability to Map Differentially Stressed Labels to Objects Predicts Language Development at 24 months in 12‐month‐olds at High Risk for Autism

Sensitivity to language‐specific stress patterns during infancy facilitates finding, mapping, and recognizing words, and early preferences for the predominate stress pattern of the infant's native language have been argued to facilitate language relevant outcomes (Ference & Curtin, 2013 Journal of Experimental Child Psychology, 116, 891; Weber et al., 2005 Cognitive Brain Research, 25, 180). We examined 12‐month‐old infant siblings of typically developing children (SIBS‐TD) and infant siblings of children diagnosed with autism spectrum disorder (ASD; SIBS‐A) on their ability to map differentially stressed labels to objects. We also examined whether success at this task relates to infants’ vocabulary size at 12 months, and more specifically to SIBS‐A's vocabulary at both 12 and 24 months. SIBS‐TD successfully mapped the word–object pairings, which related to their vocabulary comprehension at 12 months. In contrast, SIBS‐A as a group did not map the word–object pairings, which was unrelated to vocabulary size at 12 months. However, success on this task for SIBS‐A predicted expressive language abilities at 24 months using the Mullen Scales of Early Learning (MSEL; Mullen, 1995 Mullen Scales of Early Learning. Circle Pines, MN: American Guidance) and the MacArthur‐Bates Communicative Development Inventory (MB‐CDI; Fenson et al., 1993 MacArthur Communicative Development Inventory: Users Guide and Technical Manual. San Diego, CA: Singular Publishing Company). Our study is the first to demonstrate that 12‐month‐old SIBS‐A who succeed at word mapping using lexical stress are more likely to have stronger expressive language abilities at 24 months.     

Development of Infant Pointing from 10 to 12 months: The Role of Relevant Caregiver Responsiveness

Infants’ pointing frequency is a predictor of their later language abilities. Yet, predictors of pointing frequency in the first year of life are not well understood. Study 1 explored what factors in infants and caregivers at 10 months would predict the pointing frequency of infants at 12 months (N = 35). Infant‐driven predictors were infants’ fine‐motor skills and point‐following abilities. Caregiver‐mediated predictors were caregivers’ pointing frequency and responsiveness toward infants’ pointing. Relevant caregiver responsiveness at 10 months predicted infants’ pointing frequency at 12 months, controlling for the other factors and infants’ prior pointing frequency. Study 2 explored whether child‐level factors influence caregivers’ responsiveness (N = 49). We examined the hand shape of infants’ pointing (whole‐hand versus index‐finger) and the presence of point‐accompanying vocalizations. Infants’ vocalization‐accompanied points were more likely to elicit relevant responses from caregivers, while hand shapes played a less pronounced role. Together, the findings reveal an early emerging mutual relationship between infant pointing and caregiver behavior such that certain characteristics of infant pointing predict caregivers’ responsiveness, and relevant responsiveness toward infants’ pointing predicts the increase in infants’ pointing frequencies.     

A Cross‐National Investigation of the Relationship Between Infant Walking and Language Development

The acquisition of walking has recently been linked with infant language development (Walle & Campos, 2014). If this relation reflects the consequence of an epigenetic event, then it should be present regardless of when the infant typically begins to walk, the infant's culture, and the infant's native language. This study sought to replicate the previously reported link between walking and language development in American infants and investigate whether this relation exists cross‐nationally in typically developing Chinese infants exposed to Mandarin. Urban Chinese infants not only provide a distinct linguistic and cultural population in which to study this relation but also typically begin walking approximately 6 weeks later than American infants. Our results demonstrated that (1) walking infants in both the American and Chinese samples had greater receptive and productive vocabularies than same‐aged crawling infants, (2) differences between crawling and walking infants were proportionally similar in each sample, and (3) the walking‐language relation was present for both noun and non‐noun vocabularies. These findings provide further support of a relation between infant walking onset and language development, independent of age. Avenues for future research of the processes involved in this relation, as well as additional populations of interest to investigate, are discussed.     

Learned Labels Shape Pre‐speech Infants’ Object Representations

Infants rapidly learn both linguistic and nonlinguistic representations of their environment and begin to link these from around 6 months. While there is an increasing body of evidence for the effect of labels heard in‐task on infants’ online processing, whether infants’ learned linguistic representations shape learned nonlinguistic representations is unclear. In this study 10‐month‐old infants were trained over the course of a week with two 3D objects, one labeled, and one unlabeled. Infants then took part in a looking time task in which 2D images of the objects were presented individually in a silent familiarization phase, followed by a preferential looking trial. During the critical familiarization phase, infants looked for longer at the previously labeled stimulus than the unlabeled stimulus, suggesting that learning a label for an object had shaped infants’ representations as indexed by looking times. We interpret these results in terms of label activation and novelty response accounts and discuss implications for our understanding of early representational development.     

The effect of the COVID-19 pandemic on infant development and maternal mental health in the first 2 years of life

We investigated how exogenous variation in exposure to the COVID-19 pandemic during the first year of life is related to infant development, maternal mental health, and perceived stress. Ninety-three socioeconomically diverse pregnant women were recruited before the pandemic to participate in a longitudinal study. Infants ranged in age at the beginning of lockdown (0–9.5 months old), thus experiencing different durations of pandemic exposure across the first year of life. The duration of pandemic exposure was not associated with family demographic characteristics, suggesting it captured exogenous variability. We tested associations between this exogenous variation in pandemic exposure and child and family outcomes. We also examined whether mother-reported disruptive life events were correlated with child and family outcomes. We found no association between duration of pandemic exposure in the first year of life and infant socioemotional problems, infant language development, or maternal mental health and perceived stress symptoms, at 12 or 24 months. However, we found that self-reported exposure to pandemic-related disruptive life events predicted greater maternal depression, anxiety, and perceived stress at 12 months, and greater depression and anxiety at 24 months. Socioeconomic status did not moderate these associations. These findings suggest cautious optimism for infants raised during this period.     

Infants' Perception of Intonation: Is It a Statement or a Question?

The ability to distinguish phonetic variations in speech that are relevant to meaning is essential for infants' language development. Previous studies into the acquisition of prosodic categories have focused on lexical stress, lexical pitch accent, or lexical tone. However, very little is known about the developmental course of infants' perception of linguistic intonation. In this study, we investigate infants' perception of the correlates of the statement/yes–no question contrast in a language that marks this sentence type distinction only by prosodic means, European Portuguese (EP). Using a modified version of the visual habituation paradigm, EP‐learning infants at 5–6 and 8–9 months were able to successfully discriminate segmentally varied, single‐prosodic word intonational phrases presented with statement or yes–no question intonation, demonstrating that they are sensitive to the prosodic cues marking this distinction as early as 5 months and maintain this sensitivity throughout the first year. These results suggest the presence of precocious discrimination abilities for intonation across segmental variation, similarly to previous reports for lexical pitch accent, but unlike previous findings for word stress.     

Bias for Vocalic Over Consonantal Information in 6‐Month‐Olds

Human languages rely on the ability to learn and produce an indefinite number of words by combining consonants and vowels in a lawful manner. The categorization of speech representations into consonants and vowels is evidenced by the tendency of adult speakers, attested in many languages, to use consonants and vowels for different tasks. Consonants are favored in lexical tasks, while vowels are favored to learn structural regularities. Recent results suggest that this specialization is already observable at 12 months of age in Italian participants. Here, we investigated the representations of younger infants. In a series of anticipatory looking experiments, we showed that Italian 6‐month‐olds rely more on vowels than on consonants when learning the predictions made by individual words (Experiment 1) and are better at generalizing a structure when it is implemented over vowels than when it is implemented over consonants (Experiments 2 and 3). Until 6 months of age, infants thus show a general vocalic bias, which contrasts with the specialization previously observed at 12 months. These results suggest the format of speech representations changes during the second semester of life.     

Symbolic play provides a fertile context for language development

In this study, we test the hypothesis that symbolic play represents a fertile context for language acquisition because its inherent ambiguity elicits communicative behaviors that positively influence development. Infant–caregiver dyads (N = 54) participated in two 20-minute play sessions six months apart (Time 1 = 18 months, Time 2 = 24 months). During each session, the dyads played with two sets of toys that elicited either symbolic or functional play. The sessions were transcribed and coded for several features of dyadic interaction and language; infants’ linguistic proficiency was measured via parental report. The two contexts elicited different communicative and linguistic behaviors. Notably, the symbolic play condition resulted in significantly greater conversational turn-taking than functional play, and also resulted in the greater use of questions and mimetics in infant-directed speech (IDS). In contrast, caregivers used more imperative clauses in functional play. Correlational and regression analyses showed that frequent properties of symbolic play (i.e., turn-taking, yes–no questions, mimetics) were positively related to infants’ language proficiency, whereas frequent features of functional play (i.e., imperatives in IDS) were negatively related. The results provide evidence supporting the hypothesis that symbolic play is a fertile context for language development, driven by the need to negotiate meaning.     

Neural mechanisms of language development in infancy

Understanding the neural processes underpinning individual differences in early language development is of increasing interest, as it is known to vary in typical development and to be quite heterogeneous in neurodevelopmental conditions. However, few studies to date have tested whether early brain measures are indicative of the developmental trajectory of language, as opposed to language outcomes at specific ages. We combined recordings from two longitudinal studies, including typically developing infants without a family history of autism, and infants with increased likelihood of developing autism (infant-siblings) (N = 191). Electroencephalograms (EEG) were recorded at 6 months, and behavioral assessments at 6, 12, 18, 24 and 36 months of age. Using a growth curve model, we tested whether absolute EEG spectral power at 6 months was associated with concurrent language abilities, and developmental change in language between 6 and 36 months. We found evidence of an association between 6-month alpha-band power and concurrent, but not developmental change in, expressive language ability in both infant-siblings and control infants. The observed association between 6-month alpha-band power and 6-month expressive language was not moderated by group status, suggesting some continuity in neural mechanisms.     

Maternal education influences Australian infants’ language experience from six months

Disparities in children's early language skills associated with socioeconomic factors have led to many studies examining children's early language environments, but few as yet in the first year of life. This longitudinal study assessed the home language environments of 50 Australian infants, who varied in maternal education (university education, or not). Full‐day audio recordings were collected and analyzed using the LENA system when infants were aged 6–9 months and 12–15 months. Using the device‐specific analysis software, we assessed 12‐h projected counts of (1) adult speech input, (2) conversational interactions, and (3) child vocalizations. At both ages, higher maternal education was associated with higher counts of adult words and conversational turns, but not child vocalizations. The study adds to the literature by demonstrating disparities in the infants’ language experience within the first year of life, related to mothers’ education, with implications for early intervention and parenting supports.     

Effects of Seeing and Hearing Vowels on Neonatal Facial Imitation

For several decades, many authors have claimed the existence, early in life, of a tight link between perceptual and productive systems in speech. However, the question whether this link is acquired or is already present at birth remains open. This study aimed at investigating this question by employing the paradigm of neonatal facial imitation. We compared imitative responses of newborn infants presented either visual‐only, audiovisual congruent, or audiovisual incongruent models. Our results revealed that the newborns imitated significantly more quickly the movements of the model's mouth when this model was audiovisual congruent rather than visual‐only. Moreover, when observing an audiovisual incongruent model, the newborns did not produce imitative behavior. These findings, by highlighting the influence of speech perception on newborns' imitative responses, suggest that the neural architecture for perception–production is already in place at birth. The implications of these results are discussed in terms of a link between language and neonatal imitation, which could represent a precursor of more mature forms of vocal imitation and speech development in general.     

Intention or Attention Before Pointing: Do Infants’ Early Holdout Gestures Reflect Evidence of a Declarative Motive?

Gestures are the first signs of intentional communication within prelinguistic infants and can reflect various motives, including a declarative motive to share attention and interest. The ability to use gestures declaratively has been linked to later language development; therefore, it is important to understand the origins of this motive. Previous research has focused on the use of declarative pointing at around 12 months; however, other potential forms of declarative communication, such as holdout gestures, are yet to be studied in detail. The purpose of this study was to examine whether from 10 months, infants use holdouts declaratively. We elicited holdouts from 36 infants and then reacted to these gestures in four different conditions: (1) joint attention: shared interest; (2) infant attention: attended to infant; (3) toy attention: attended to toy; (4) ignore: gesture was not attended to. Infants’ behavioral responses were recorded. When the experimenter engaged in joint attention, infants were significantly more likely to display a positive attitude and produced fewer re‐engagement attempts. In contrast, the three non‐joint attention conditions displayed significantly higher negative attitudes and attempts to re‐engage the experimenter. We conclude that infants display declarative communication prior to 12 months, resetting the age at which these more complex skills emerge.     

Developmental Change in Action Perception: Is Motor Experience the Cause?

Human actions are complex stimuli containing several perceptual dimensions an observer could attend to. Research indicates that attention to the perceptual dimensions of action undergoes a process of perceptual narrowing between 4 and 10 months, during which infants’ attention to configural and temporal information in action decreases over time, while attention to hand information is maintained. This research explored whether infants’ active experience with grasping is related to perceptual narrowing in action. Across two studies, we tested 6‐month‐old infants’ attention to changes in these action dimensions and also assessed their grasping ability. Infants who were more proficient at grasping showed a pattern more consistent with perceptual narrowing (decreasing attention to configural and temporal information) relative to those less proficient at grasping, especially for attention to configural information. In addition, attention to hand information appears to undergo U‐shaped development between 4 and 10 months, as 6‐month‐olds did not recover attention to the hand change. These findings add to a growing body of research showing that infants’ motor experience broadly influences their perception of others’ action and may follow a complex developmental pathway that diverges from perceptual narrowing over the first year.     

It don't go both ways: Limited bidirectionality in sociolinguistic perception

This article explores the sociolinguistic perception of morphosyntactic variation, using sociolinguistic priming experiments. Two experiments tested participants' perception of the connection between social status and variation in two English subject‐verb agreement constructions: there's+NP and NP+don't. Experiment 1 tested sentence perception and found that exposure to non‐standard agreement boosted the perception of non‐standard agreement, but only for there's+NP. Social status cues had no effect on sentence perception. Experiment 2 tested speaker perception and found that participants were more likely to believe that non‐standard agreement was produced by low‐status than high‐status speakers. Results suggest that, especially for heavily stigmatized variables, non‐standard sentences strongly constrain the social judgments made by speakers, yet social cues do not necessarily constrain linguistic perception. The results suggest that the perceptual relationship between linguistic and social knowledge may be one of only limited bidirectionality. Implications for sociolinguistic perception and exemplar‐theoretic accounts of sociolinguistic competence are discussed.     

Phonological Specificity in 12‐ and 17‐Month‐Old French‐Speaking Infants

The literature reports some contradictory results on the degree of phonological specificity of infants’ early lexical representations in the Romance language, French, and Germanic languages. It is not clear whether these discrepancies are because of differences in method, in language characteristics, or in participants’ age. In this study, we examined whether 12‐ and 17‐month‐old French‐speaking infants are able to distinguish well‐pronounced from mispronounced words (one or two features of their initial consonant). To this end, 46 infants participated in a preferential looking experiment in which they were presented with pairs of pictures together with a spoken word well pronounced or mispronounced. The results show that both 12‐ and 17‐month‐old infants look longer at the pictures corresponding to well‐pronounced words than to mispronounced words, but show no difference between the two mispronunciation types. These results suggest that, as early as 12 months, French‐speaking infants, like those exposed to Germanic languages, already possess detailed phonological representations of familiar words.     

Self‐conscious Shyness: Growth during Toddlerhood,Strong Role of Genetics,and No Prediction from Fearful Shyness

Fearful and self‐conscious subtypes of shyness have received little attention in the empirical literature. Study aims included the following: (1) determining whether fearful shyness predicted self‐conscious shyness, (2) describing development of self‐conscious shyness, and (3) examining genetic and environmental contributions to fearful and self‐conscious shyness. Observed self‐conscious shyness was examined at 19, 22, 25, and 28 months in same‐sex twins (MZ = 102, DZ = 111, missing zygosity = 3 pairs). Self‐conscious shyness increased across toddlerhood, but onset was earlier than predicted by theory. Fearful shyness (observed [6 and 12 months] and parents’ reports [12 and 22 months]) was not predictive of self‐conscious shyness. Independent genetic factors made strong contributions to parent‐reported (but not observed) fearful shyness (additive genetic influence = .69 and .72 at 12 and 22 months, respectively) and self‐conscious shyness (additive genetic influence = .90 for the growth model intercept). Results encourage future investigation of patterns of change and inter‐relations in shyness subtypes.     

Persona‐based information shapes linguistic perception: Valley Girls and California vowels

This paper investigates the effect of persona‐based information on implicit linguistic perceptions of a sociolinguistic feature – the backed trap vowel. trap ‐backing is associated both with macro‐social region (California) and with a particular persona that inhabits this region (the Valley Girl). An eye‐tracking paradigm is used to examine these associations in early, automatic stages of perception. One group of listeners was told the speaker was from California, while another group was told that the speaker had been described as a Valley Girl. Findings demonstrate that both the California information and the Valley Girl information caused listeners to expect the speaker to exhibit trap ‐backing. While previous studies have highlighted the influence of macro‐sociological categories on linguistic perception, the present study suggests that persona‐based social meanings can also serve to influence perception, supporting theories that foreground personae as social constructs crucial to interaction.