Maternal Sensitivity and the Learning‐Promoting Effects of Depressed and Nondepressed Mothers' Infant‐Directed Speech

The hypothesis that aspects of current mother‐infant interactions predict an infant's response to maternal infant‐directed speech (IDS) was tested. Relative to infants of nondepressed mothers, those of depressed mothers acquired weaker voice‐face associations in response to their own mothers' IDS in a conditioned‐attention paradigm, although this was partially attributable to demographic differences between the 2 groups. The extent of fundamental frequency modulation (ΔF₀) in maternal IDS was smaller for infants of depressed than nondepressed mothers, but did not predict infant learning. However, Emotional Availability Scale ratings of maternal sensitivity, coded from videotapes of mothers and infants engaged in a brief play interaction, were significant predictors of infant learning, even after maternal depression, its demographic correlates, and antidepressant medication use had been taken into account. These findings are consistent with a role for experience‐dependent processes in determining the effects of IDS on infant learning.     

A Privileged Status for Male Infant‐Directed Speech in Infants of Depressed Mothers? Role of Father Involvement

Prior research showed that 5‐ to 13‐month‐old infants of chronically depressed mothers did not learn to associate a segment of infant‐directed speech produced by their own mothers or an unfamiliar nondepressed mother with a smiling female face, but showed better‐than‐normal learning when a segment of infant‐directed speech produced by an unfamiliar nondepressed father signaled the face. Here, learning in response to an unfamiliar nondepressed father’s infant‐directed speech was studied as a function both of the mother’s depression and marital status, a proxy measure of father involvement. Infants of unmarried mothers on average did not show significant learning in response to the unfamiliar nondepressed father’s infant‐directed speech. Infants of married mothers showed significant learning in response to male infant‐directed speech, and infants of depressed, married mothers showed significantly stronger learning in response to that stimulus than did infants of nondepressed, married mothers. Several ways in which father involvement may positively or negatively affect infant responsiveness to male infant‐directed speech are discussed.     

Attention to Maternal Multimodal Naming by 6‐ to 8‐Month‐Old Infants and Learning of Word–Object Relations

We examined whether mothers' use of temporal synchrony between spoken words and moving objects, and infants' attention to object naming, predict infants' learning of word–object relations. Following 5 min of free play, 24 mothers taught their 6‐ to 8‐month‐olds the names of 2 toy objects, Gow and Chi, during a 3‐min play episode. Infants were then tested for their word mapping. The videotaped episodes were coded for mothers' object naming and infants' attention to different naming types. Results indicated that mothers' use of temporal synchrony and infants' attention during play covaried with infants' word‐mapping ability. Specifically, infants who switched eye gaze from mother to object most frequently during naming learned the word–object relations. The findings suggest that maternal naming and infants' word‐mapping abilities are bidirectionally related. Variability in infants' attention to maternal multimodal naming explains the variability in early lexical‐mapping development.     

Early Word Segmentation in Naturalistic Environments: Limited Effects of Speech Register

We examined 7.5‐month‐old infants' ability to segment words from infant‐ and adult‐directed speech (IDS and ADS). In particular, we extended the standard design of most segmentation studies by including a phase where infants were repeatedly exposed to target word recordings at their own home (extended exposure) in addition to a laboratory‐based familiarization. This enabled us to examine infants' segmentation of words from speech input in their naturalistic environment, extending current findings to learning outside the laboratory. Results of a modified preferential‐listening task show that infants listened longer to isolated tokens of familiarized words from home relative to novel control words regardless of register. However, infants showed no recognition of words exposed to during purely laboratory‐based familiarization. This indicates that infants succeed in retaining words in long‐term memory following extended exposure and recognizing them later on with considerable flexibility. In addition, infants segmented words from both IDS and ADS, suggesting limited effects of speech register on learning from extended exposure in naturalistic environments. Moreover, there was a significant correlation between segmentation success and infants' attention to ADS, but not to IDS, during the extended exposure phase. This finding speaks to current language acquisition models assuming that infants' individual attention to language stimuli drives successful learning.     

Developmental Changes in Infants’ Ability to Cope with Dialect Variation in Word Recognition

Toward the end of their first year of life, infants’ overly specified word representations are thought to give way to more abstract ones, which helps them to better cope with variation not relevant to word identity (e.g., voice and affect). This developmental change may help infants process the ambient language more efficiently, thus enabling rapid gains in vocabulary growth. One particular kind of variability that infants must accommodate is that of dialectal accent, because most children will encounter speakers from different regions and backgrounds. In this study, we explored developmental changes in infants’ ability to recognize words in continuous speech by familiarizing them with words spoken by a speaker of their own region (North Midland‐American English) or a different region (Southern Ontario Canadian English), and testing them with passages spoken by a speaker of the opposite dialectal accent. Our results demonstrate that 12‐ but not 9‐month‐olds readily recognize words in the face of dialectal variation.     

Monolingual and bilingual infants’ word segmentation abilities in an inter‐mixed dual‐language task

Previous studies show that young monolingual infants use language‐specific cues to segment words in their native language. Here, we asked whether 8 and 10‐month‐old infants (N = 84) have the capacity to segment words in an inter‐mixed bilingual context. Infants heard an English‐French mixed passage that contained one target word in each language, and were then tested on their recognition of the two target words. The English‐monolingual and French‐monolingual infants showed evidence of segmentation in their native language, but not in the other unfamiliar language. As a group, the English‐French bilingual infants segmented in both of their native languages. However, exploratory analyses suggest that exposure to language mixing may play a role in bilingual infants’ segmentation skills. Taken together, these results indicate a close relation between language experience and word segmentation skills.     

Word Level Stress and Lexical Processing in 17‐Month‐Old Infants

Detailed representations enable infants to distinguish words from one another and more easily recognize new words. We examined whether 17‐month‐old infants encode word stress in their familiar word representations. In Experiment 1, infants were presented with pairs of familiar objects while hearing a target label either properly pronounced with the correct stress (e.g., baby /’be?bi/) or mis‐pronounced with the incorrect stress pattern (e.g., baby /be?’bi/). Infants mapped both the correctly stressed and mis‐stressed labels to the target objects; however, they were slower to fixate the target when hearing the mis‐stressed label. In Experiment 2, we examined whether infants appreciate that stress has a nonproductive role in English (i.e., altering the stress of a word does not typically signal a change in word meaning) by presenting infants with a familiar object paired with a novel object while hearing either correctly stressed or mis‐stressed familiar words (Experiment 2). Here, infants mapped the correctly stressed label to the familiar object but did not map the mis‐stressed label reliably to either the target or distractor objects. These findings suggest that word stress impacts the processing of familiar words, and infants have burgeoning knowledge that altering the stress pattern of a familiar word does not reliably signal a new referent.     

Infant‐directed speech to infants at risk for dyslexia: A novel cross‐dyad design

When mothers speak to infants at risk for developmental dyslexia, they do not hyperarticulate vowels in their infant‐directed speech (IDS). Here, we used an innovative cross‐dyad design to investigate whether the absence of vowel hyperarticulation in IDS to at‐risk infants is a product of maternal infant‐directed behavior or of infants’ parent‐directed cues. Interactions between mothers and infants who were at risk or not at risk for dyslexia were recorded in three conditions: when mothers interacted with (a) their own infants, (b) infants who were not their own but of the same risk status, and (c) infants who were not their own and of the opposite risk status. This design revealed both infant and parent effects. Mothers of not‐at‐risk infants hyperarticulated vowels significantly more when speaking to not‐at‐risk than to at‐risk infants. In contrast, mothers of at‐risk infants hyperarticulated vowels significantly less than NAR mothers, and this was irrespective of infant status. Mothers of not‐at‐risk infants thus adjusted their IDS to the infant's risk status, while mothers of at‐risk infants did not. We suggest that IDS is determined reciprocally by characteristics of both partners in the dyad: Both infant and maternal factors are essential for the vowel hyperarticulation component of IDS.     

The Quality of Spontaneous Movements of Preterm Infants: Associations with the Quality of Mother–Infant Interaction

The assessment of the quality of infants’ spontaneous movements is a diagnostic tool for the young nervous system. We examined whether it relates to the quality of the interactions between infants born preterm and their mothers. Thirty‐nine healthy infants born preterm (M_{age in weeks} = 14.59, SD = 2.21; 38.46% female) and their mothers participated in the study. Infants’ quality of spontaneous movements was assessed using the General Movement Assessment according to Prechtl (Prechtl, Early Human Development 1990, 23, 151). A new measurement was employed to evaluate the following aspects of the mother–infant interaction: maternal sensitivity in the motor modality (i.e., when touching, picking up, holding, and putting down the infant), maternal sensitivity in the modalities of vocalization and eye contact, and infants’ positive engagement. Several aspects of infants’ quality of movements were associated with maternal sensitivity in the motor modality and infants’ positive engagement, but not with maternal sensitivity in the modalities of vocalization and eye contact. These findings suggest that the quality of infants’ spontaneous movements may explain some of the variability in the interactions between infants born preterm and their mothers. The results also highlight the importance of differentiating between the modalities of mothers’ behavior when assessing their sensitivity. Implications for research and practice with families of preterm infants are discussed.     

From Syllables to Syntax: Multilevel Statistical Learning by 12‐Month‐Old Infants

To successfully acquire language, infants must be able to track multiple levels of regularities in the input. In many cases, regularities only emerge after some learning has already occurred. For example, the grammatical relationships between words are only evident once the words have been segmented from continuous speech. To ask whether infants can engage in this type of learning process, 12‐month‐old infants in 2 experiments were familiarized with multiword utterances synthesized as continuous speech. The words in the utterances were ordered based on a simple finite‐state grammar. Following exposure, infants were tested on novel grammatical and ungrammatical sentences. The results indicate that the infants were able to perform 2 statistical learning tasks in sequence: first segmenting the words from continuous speech, and subsequently discovering the permissible orderings of the words. Given a single set of input, infants were able to acquire multiple levels of structure, suggesting that multiple levels of representation (initially syllable‐level combinations, subsequently word‐level combinations) can emerge during the course of learning.     

Infants' First Words are not Phonetically Specified: Own Name Recognition in British English‐Learning 5‐Month‐Olds

By the end of their first year of life, infants’ representations of familiar words contain phonetic detail; yet little is known about the nature of these representations at the very beginning of word learning. Bouchon et al. ( 2015 ) showed that French‐learning 5‐month‐olds could detect a vowel change in their own name and not a consonant change, but also that infants reacted to the acoustic distance between vowels. Here, we tested British English‐learning 5‐month‐olds in a similar study to examine whether the acoustic/phonological characteristics of the native language shape the nature of the acoustic/phonetic cues that infants pay attention to. In the first experiment, British English‐learning infants failed to recognize their own name compared to a mispronunciation of initial consonant (e.g., Molly versus Nolly) or vowel (e.g., April versus Ipril). Yet in the second experiment, they did so when the contrasted name was phonetically dissimilar (e.g., Sophie versus Amber). Differences in phoneme category (stops versus continuants) between the correct consonant versus the incorrect one significantly predicted infants’ own name recognition in the first experiment. Altogether, these data suggest that infants might enter into a phonetic mode of processing through different paths depending on the acoustic characteristics of their native language.     

Effects of Familiarity and Feeding on Newborn Speech–Voice Recognition

Newborn infants preferentially orient to familiar over unfamiliar speech sounds. They are also better at remembering unfamiliar speech sounds for short periods of time if learning and retention occur after a feed than before. It is unknown whether short‐term memory for speech is enhanced when the sound is familiar (versus unfamiliar) and, if so, whether the effect is further enhanced by feeding. We used a two‐factorial design and randomized infants to one of four groups: prefeed‐unfamiliar, prefeed‐familiar, postfeed‐unfamiliar, and postfeed‐familiar. Memory for either familiar or unfamiliar speech (the infant's mother saying “baby” versus a female stranger saying “beagle”) was assessed using head turning to sound in an habituation–recovery paradigm and a retention delay of 85 sec either before or after a typical milk feed. Memory for the familiar speech–voice was enhanced relative to the unfamiliar speech–voice, expressed by significantly less head turning toward the habituated sound stimulus when it was re‐presented after the delay. Memory for familiar or unfamiliar speech was not significantly enhanced from pre‐ to postfeeding, nor was there a significant interaction. This is the first demonstration in newborns that familiarity enhances short‐term memory for speech–voice sound.     

Language Experience Shapes the Development of the Mutual Exclusivity Bias

Halberda (2003) demonstrated that 17‐month‐old infants, but not 14‐ or 16‐month‐olds, use a strategy known as mutual exclusivity (ME) to identify the meanings of new words. When 17‐month‐olds were presented with a novel word in an intermodal preferential looking task, they preferentially fixated a novel object over an object for which they already had a name. We explored whether the development of this word‐learning strategy is driven by children’s experience of hearing only one name for each referent in their environment by comparing the behavior of infants from monolingual and bilingual homes. Monolingual infants aged 17–22 months showed clear evidence of using an ME strategy, in that they preferentially fixated the novel object when they were asked to “look at the dax.” Bilingual infants of the same age and vocabulary size failed to show a similar pattern of behavior. We suggest that children who are raised with more than one language fail to develop an ME strategy in parallel with monolingual infants because development of the bias is a consequence of the monolingual child’s everyday experiences with words.     

The Organization of Words and Symbolic Gestures in 18‐Month‐Olds’ Lexicons: Evidence From a Disambiguation Task

Infants’ early communicative repertoires include both words and symbolic gestures. The current study examined the extent to which infants organize words and gestures in a single unified lexicon. As a window into lexical organization, eighteen‐month‐olds’ (N = 32) avoidance of word–gesture overlap was examined and compared with avoidance of word–word overlap. The current study revealed that when presented with novel words, infants avoided lexical overlap, mapping novel words onto novel objects. In contrast, when presented with novel gestures, infants sought overlap, mapping novel gestures onto familiar objects. The results suggest that infants do not treat words and gestures as equivalent lexical items and that during a period of development when word and symbolic gesture processing share many similarities, important differences also exist between these two symbolic forms.     

Vois‐Tu Le Kem? Do You See the Bos? Foreign Word Learning at 14 Months

How easily can infants regularly exposed to only one language begin to acquire a second one? In three experiments, we tested 14‐month‐old English and French monolingual infants’ ability to learn words presented in foreign language sentence frames. Infants were trained on two novel word‐object pairings and then tested using a preferential looking task. Word forms were phonetically and phonotactically legal in both languages, and cross‐spliced across conditions, so only the sentence frames established the word as native or foreign. In Experiment 1, infants were taught one native and one foreign word and successfully learned both. In Experiment 2 and 3, infants were taught two foreign words, but only showed successful learning of the first word they encountered. These results demonstrate that infants can successfully learn words embedded in foreign language sentences, but this is more challenging than native word learning. More broadly, they show that the sentential context of a novel word, and not just the word form itself, influences infants’ early word learning.     

Prenatal Reflective Functioning and Accumulated Risk as Predictors of Maternal Interactive Behavior During Free Play,the Still‐Face Paradigm,and Two Teaching Tasks

This study examined whether prenatal reflective functioning (RF) was related to mothers’ interactive style across contexts with their 6‐month‐old infants (M age = 6.02 months, SD = 0.41, 54% boys), and to what extent quality of prenatal RF could account for the influence of accumulated risk on maternal interactive behavior. Accumulated risk was defined as the sum‐score of a selection of risk factors that have been associated with suboptimal infant development. Mother–infant dyads (N = 133) were observed during free play, two teaching tasks, and the Still‐Face Paradigm (SFP). Better prenatal RF was associated with more positive maternal behavior in all settings and less negative behavior during teaching and SFP reengagement. Accumulated risk and prenatal RF predicted shared variance in maternal interactive behavior (with unique predictive effects observed only for RF on sensitivity during teaching and SFP play, and for accumulated risk on sensitivity and positive engagement during SFP play, and internalizing‐helplessness during SFP reengagement). Accumulated risk had an indirect effect on maternal sensitivity during teaching and SFP play through prenatal RF. These findings suggest not only that RF may be targeted prenatally to improve mother–infant interactions, but also that enhancing RF skills may ameliorate some of the negative consequences from more stable perinatal risk factors that influence parent–child interactions.     

Is a Bird an Apple? The Effect of Speaker Labeling Accuracy on Infants' Word Learning,Imitation, and Helping Behaviors

This study examined infants' sensitivity to a speaker's verbal accuracy and whether the reliability of the speaker had an effect on their selective trust. Forty‐nine 18‐month‐old infants were exposed to a speaker who either accurately or inaccurately labeled familiar objects. Subsequently, the speaker administered a series of tasks in which infants had an opportunity to: learn a novel word, imitate the speaker's “irrational” actions, and help the speaker obtain an out‐of‐reach object. In contrast to infants in the accurate (reliable) condition, those in the inaccurate (unreliable) condition performed more poorly on a word‐learning task and were less likely to imitate. All infants demonstrated high rates of instrumental helping behavior. These results are the first to demonstrate that infants as young as 18 months of age cannot only detect a speaker's verbal inaccuracy but also use this information to attenuate their word recognition and learning of novel actions.     

Maternal input and infants’ response to infant‐directed speech

Caregivers typically use an exaggerated speech register known as infant‐directed speech (IDS) in communication with infants. Infants prefer IDS over adult‐directed speech (ADS) and IDS is functionally relevant in infant‐directed communication. We examined interactions among maternal IDS quality, infants’ preference for IDS over ADS, and the functional relevance of IDS at 6 and 13 months. While 6‐month‐olds showed a preference for IDS over ADS, 13‐month‐olds did not. Differences in gaze following behavior triggered by speech register (IDS vs. ADS) were found in both age groups. The degree of infants’ preference for IDS (relative to ADS) was linked to the quality of maternal IDS infants were exposed to. No such relationship was found between gaze following behavior and maternal IDS quality and infants’ IDS preference. The results speak to a dynamic interaction between infants’ preference for different kinds of social signals and the social cues available to them.     

Functional Parallelism of Detailed and Rough Speech Processing at the End of Infancy

Although realization of the same speech sound is far from being consistent across different contexts, speech recognition has to rely on phonetic detail in order to detect words. So far, it appeared that young infants cannot avoid noticing subtle speech sound variation whenever it occurs. Only later on, they are able to tolerate speech sound variation in some word recognition tasks. Here, we test whether this ability is associated with the time infants start storing their first word forms. We recorded event‐related potentials (ERPs) in a priming paradigm. German words (targets) followed syllables (primes) with a different amount of phoneme overlap. We tested infants at three, six, and nine months after birth. ERPs reflected sensitivity to prime‐target variation in a single phoneme in three‐month‐olds, tolerance to this in six‐month‐olds, and both processing aspects in nine‐month‐olds. Our findings reveal individual developmental priorities for different aspects of speech processing, with very detailed speech processing dominating at around 3 months, rough processing dominating at around half a year after birth, and an architecture of parallel rough and detailed processing at around 9 months. Functional parallelism at the end of infancy might explain the heterogeneous pattern of results regarding the degree of acoustic detail that toddlers appear to consider at different ages and across different paradigms.