Parental Speech at 6 Months Predicts Joint Attention at 12 Months

In a prospective longitudinal study of a representative community sample (N = 264), mothers' references to infants' mental states were coded during a topic‐sharing task in the home at 6 months. Joint attention behaviour was assessed in the laboratory at 12 months. Individual joint attention skills (gaze following, gaze alternating, and declarative pointing) were significantly inter‐correlated, with a single factor accounting for 68% of the variance. Mothers' references to infants' mental states at 6 months predicted infants' joint attention at 12 months. The association was not explained by sociodemographic characteristics of the family, the mother's mental state, or by the quantity or acoustic properties of her speech. However, variability in pitch of maternal speech was an independent predictor of the infants' later joint attention skills. Taken together, these findings suggest that mothers' infant‐directed speech fosters infants' attentive participation in topic‐sharing interactions, which in turn provide an important arena in which joint attention skills develop over the first year of life.     

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.     

The Value of Vocalizing: 10‐Month‐Olds' Vocal Usage Relates to Language Outcomes at 15 Months

The interaction between infant's communicative competence and responsiveness of caregivers facilitates the transition from prelinguistic to linguistic communication. It is thus important to know how infants' communicative behavior changes in relation to different caregiver responses; furthermore, how infants' modification of communicative behavior relates to language outcomes. We investigated 39 10‐month‐old infants' communication as a function of mothers' attention and responses and the relationship to language outcomes at 15 months. We elicited infants' communicative behavior in three conditions: (1) joint attention: Mothers were visually attending and responding to infants' attention and interest; (2) available: Mothers were visually attending to infants, but not responding contingently to infants' attention and interest; (3) unavailable: Mothers were not attending to infants nor responding to them. Infants vocalized more when mothers attended and responded to them (conditions 1 and 2) than when mothers did not (condition 3), but infants' gesture and gesture‐vocal production did not differ across conditions. Furthermore, infants' production of a higher proportion of vocalizations in the unavailable condition relative to the joint attention condition correlated with, and predicted, infants' language scores at 15 months. Thus, infants who appear to be aware of the social effects of vocalizations may learn words better.     

The Microstructure of Infants' Gaze as They View Adult Shifts in Overt Attention

We presented infants (5, 6, 9, and 12 months old) with movies in which a female model turned toward and fixated 1 of 2 toys placed on a table. Infants' gaze was measured using a Tobii 1750 eye tracker. Six‐, 9‐, and 12‐month‐olds' first gaze shift from the model's face (after the model started turning) was directed to the attended toy. The 5‐month‐olds performed at random. Following this initial response, 5‐, 6‐, and 9‐month‐olds performed more gaze shifts to the attended target; 12‐month‐olds performed at random. Infants at all ages displayed longer looking times to the attended toy. We discuss a number of explanations for 5‐month‐olds' ability to follow a shift in overt attention by an adult after an initially random response, including the possibility that infants' initial gaze response strengthens the representation of the objects in the peripheral visual field.     

Fine‐Grained Analysis of Motionese: Eye Gaze,Object Exchanges,and Action Units in Infant‐Versus Adult‐Directed Action

Mothers modify their actions when demonstrating objects to infants versus adults. Such modifications have been called infant‐directed action (IDA) or motionese (Brand, Baldwin, & Ashburn, 2002). We investigated the IDA features of interactiveness and simplification by quantifying eye gaze, object exchanges, and action units enacted between exchanges in 42 mothers' demonstrations of novel objects to infants (6–8 months or 11–13 months) or adults. We found more eye gaze, more object exchanges, and fewer action types per turn in demonstrations to infants relative to adults. Unlike prior research using global measurements, we detected differences in behavior directed at infants of different ages: Shorter, more frequent gazes and more exchanges characterized demonstrations to older versus younger infants. These findings indicate the fruitfulness of fine‐grained analysis of IDA, and further clarify how adults may support infants' processing of human motion.     

Infants' Response to Maternal Mirroring in the Still Face and Replay Tasks

Infants' response to maternal mirroring was investigated in 4‐month‐old infants. Mother–infant dyads participated in the still face and replay tasks. Infants were grouped by those whose mothers did and did not mirror their behavior in the interactive phases of the tasks. In the still face task, infants with maternal mirroring showed more attention, smiling, and positive vocalizations across the phases, although both groups of infants demonstrated the still‐face effect with attention and smiling. Infants' social bidding to the mother during the still‐face phase correlated with mothers' mirroring behavior. In the replay task, infants with maternal mirroring demonstrated carryover effects with smiling; infants without maternal mirroring showed no awareness of change in their mothers' behavior. In both the still face and replay tasks, infants with maternal mirroring were more engaged with their mothers. Results suggest that maternal mirroring of infants' behavior affects infants' detection of, and response to, reciprocal interaction.     

Separable Attentional Predictors of Language Outcome

The aim of this study was to examine the combined influences of infants' attention and use of social cues in the prediction of their language outcomes. This longitudinal study measured infants' visual attention on a distractibility task (11 months), joint attention (14 months), and language outcomes (word–object association, 14 months; MBCDI vocabulary size and multi‐word productions at 18 months of age). Path analyses were conducted for two different language outcomes. The analysis for vocabulary revealed unique direct prediction from infants' visual attention on a distractibility task (i.e., maintaining attention to a target event in the presence of competing events) and joint attention (i.e., more frequent response to tester's bids for attention) for larger vocabulary size at outcome; this model accounted for 48% of variance in vocabulary, after controlling for baseline communication status (assessed at 11 months). The analysis for multi‐word productions yielded direct effects for infants' distractibility, but not joint attention; this model accounted for 45% of variance in multi‐word productions, again after controlling for baseline communication status. Indirect effects were not significant in either model. Results are discussed in light of the unique predictive role of attentional factors and social/attention cues for emerging language.     

Disentangling the Effects of an Adult Model's Eye Gaze and Head Orientation on Young Infants' Processing of a Previously Attended Object

In order to disentangle the effects of an adult model's eye gaze and head orientation on infants' processing of objects attended to by the adult, we presented 4‐month‐olds with faces that either (1) shifted eye gaze toward or away from an object while the head stayed stationary or (2) that turned their head while maintaining gaze directed straight ahead. Infants' responses to the previously attended and unattended objects were measured using eye‐tracking and event‐related potentials. In both conditions, infants responded to objects that were not cued by the adult's head or eye gaze shift with more visual attention and an increased negative central (Nc) component relative to cued objects. This suggests that cued objects had been encoded more effectively, whereas uncued objects required further processing. We conclude that eye gaze and head orientation act independently as cues to direct infants' attention and object processing. Both head orientation and eye gaze, when presented in motion, even override the effects of incongruent stationary information from the other kind of cue.     

Mothers' Verbal and Nonverbal Strategies in Relation to Infants' Object‐Directed Actions in Real Time and Across the First Three Years in Ethnically Diverse Families

We examined maternal behavioral strategies in relation to infants' object‐directed actions in real time and over developmental time in 206 mother–infant dyads from African American, Dominican immigrant, and Mexican immigrant backgrounds. Mothers were asked to share a set of beads and strings with their infants when children were 14, 24, and 36 months. We coded three types of maternal strategies—eliciting attention, instructive assistance, and encouragement—which could be expressed verbally (e.g., “look”, “turn it”, “good job!”) or physically (i.e., through gestures, hands‐on guidance, or transfer of objects). We also coded infants' unassisted bead‐stringing. Across ethnic groups and ages, mothers' hands‐on guidance and object transfer increased the likelihood that infants would follow with unassisted bead‐stringing during real‐time interaction. Over developmental time, mothers modified their strategies: They displayed fewer attention‐getting strategies and more encouragement across infant ages, and peaked in their provision of instructive assistance when infants were 24 months. Additionally, Mexican mothers displayed more nonverbal strategies (e.g., gestures, hands‐on guidance) than did African American and/or Dominican mothers, who displayed more verbal strategies (e.g., attention‐getting and encouraging language). Developmental and real‐time patterns in mother–infant object‐related interactions generalize across ethnicities, although mothers' emphases on specific strategies are culture specific.     

How Mothers Encourage and Discourage Infants' Motor Actions

The content of mothers' emotional, verbal, and gestural communication to their infants was examined under conditions of potential physical risk in a laboratory motor task. Mothers encouraged and discouraged their 12‐ and 18‐month‐old infants to crawl or walk down a sloping walkway. Mothers expressed positive affect on nearly every trial. They rarely expressed purely negative affect in their faces and voices, even when discouraging. Instead, they discouraged infants with a mixture of positive and negative expressions. In both encourage and discourage conditions, mothers coupled their emotional messages with rich verbal and gestural information to elicit infants' attention, regulate their location, guide their actions, and describe the situation and potential consequences of their actions. The content of mothers' communication was attuned to infants' age and locomotor experience.     

Depressed and Well Mothers' Emotion Interpretation Accuracy and the Quality of Mother—Infant Interaction

The inadequate parenting associated with mothers' depression may be related to mothers' problems in interpreting infants' emotional expressions. The relations between depressed and well mothers' accuracy at interpreting babies' facial expressions and the quality of the mothers' interactions with their infants were examined. In partial support of our hypotheses, depressed mothers' level of depressive symptoms was associated with less accuracy, especially regarding positive emotions. Contrary to expectations, depressed mothers did not differ from well mothers in terms of their emotion accuracy. Furthermore, depressed mothers' accuracy at interpreting infants' emotions was not significantly related to the quality of their interaction with their infants; in contrast, well mothers' accuracy for infants' negative emotions was associated with better interaction quality. These findings provide new information about depressed mothers' emotional interpretations and their parenting. The different pattern of findings for depressed and well mothers suggests that other mediating factors are important, which are discussed.     

Experimenter Affective Expression and Gaze Following in 7‐Month‐Olds

The study of gaze following in infants younger than 12 months of age has emphasized the effects of gesture, type of target, and its position or placement. This experiment extends this literature by examining the effects of adults' affective expression on 7‐month‐olds' gaze following. The effects of 3 affective expressions—happy, sad, and neutral—on 7‐month‐olds' frequency of gaze following were examined. The results indicated that infants more frequently followed the gaze of an adult posing a neutral expression than that of an adult posing either a happy or a sad expression. The infants also looked proportionately longer toward the indicated target when the adult's expression was neutral. The results are interpreted in terms of infants' flexibility of attention.     

The Cat is out of the Bag: The Joint Influence of Previous Experience and Looking Behavior on Infant Categorization

We examined the effect of 4‐month‐old infants' previous experience with dogs, cats, or both and their online looking behavior on their learning of the adult‐defined category of cat in a visual familiarization task. Four‐month‐old infants' (N = 123) learning in the laboratory was jointly determined by whether or not they had experience with pets at home and how much they shifted their gaze back and forth between the stimuli during familiarization. Specifically, only infants with pets at home who also exhibited high levels of switching during familiarization remembered the individual cat exemplars or formed a summary representation of those cats. These results are consistent with recent theorizing about the processes of how infants' categorical representations are formed, and provide new understanding into how infants' categorization unfolds over time.     

Correlates of infant pointing frequency in the first year

This study examines the emergence of concurrent correlates of infant pointing frequency with the aim of contributing to its ontogenetic theories. We measured monthly from 8 to 12 months infants' (N = 56) index-finger pointing frequency along with several candidate correlates: (1) family socioeconomic status (SES), (2) mothers' pointing production, and (3) infants' point following to targets in front of and behind them. Results revealed that (1) infants increased their pointing frequency across age, but high-SES infants had a steeper increase, and a higher pointing frequency than low-SES infants from 10 months onward, (2) maternal pointing frequency was not associated with infant pointing frequency at any age, (3) infants' point following abilities to targets behind their visual fields was positively associated with their pointing frequency at 12 months, after pointing had already emerged around 10 months. Findings suggest that family SES impacts infants' pointing development more generally, not just through maternal pointing. The association between pointing and following points to targets behind, but not in front, suggests that a higher level of referential understanding emerges after, and perhaps through the production of pointing.     

Age‐Specific Preferences for Infant‐Directed Affective Intent

This study examined the developmental course of infants' attentional preferences for 3 types of infant‐directed affective intent, which have been shown to be commonly used at particular ages in the first year of life. Specifically, Kitamura and Burnham (2003) found mothers' tone of voice in infant‐directed speech is most comforting between birth and 3 months, most approving at 6 months, and most directive at 9 months. Thus, the aim of this study was to assess whether there is a relation between the type of affective intent used by mothers at each age point, and infants' affective intent preferences. Each infant group, 3‐, 6‐, and 9‐month‐olds, was played the 3 types of affective intent alternating across a single test session. When analyzed across age, the interactions revealed the predicted developmental trajectory; that is, infant preferences transformed between 3 and 6 months from comforting to approving, and between 6 and 9 months, from approving to directive. However, when analyzed separately by age, it was shown that 3‐month‐olds preferred comforting to other types; 6‐month‐olds preferred approving to directive, but listened equally to approving and comforting; and 9‐month‐olds showed no preference for any type of affective intent. Because it was possible that 9‐month‐olds were more focused on phonetic and phonotactic information, a new group of 9‐month‐olds was tested with intonation‐only versions of the 3 affective intent types. Under these conditions, they were found to prefer directive to comforting, but not directive to approving types. The results of this study have implications for what infants pay attention to in their social and linguistic environment over the course of the first year.     

The effect of masks on the visual preference for faces in the first year of life

To prevent the spread of COVID-19, face masks were mandatory in many public spaces around the world. Since faces are the gateway to early social cognition, this raised major concerns about the effect face masks may have on infants' attention to faces as well as on their language and social development. The goal of the present study was to assess how face masks modulate infants' attention to faces over the course of the first year of life. We measured 3, 6, 9, and 12-month-olds’ looking behavior using a paired visual preference paradigm under two experimental conditions. First, we tested infants' preference for upright masked or unmasked faces of the same female individual. We found that regardless of age, infants looked equally long at the masked and unmasked faces. Second, we compared infants' attention to an upright masked versus an inverted masked face. Three- and 6-month-olds looked equally long to the masked faces when they were upright or inverted. However, 9- and 12-month-old infants showed a novelty preference for the inverted masked face. Our findings suggest that more experience with faces, including masked faces, leads to efficient adaptations of infants' visual system for processing impoverished social stimuli, such as partially occluded faces.     

Maternal Depressive Symptoms and 6‐Month‐Old Infants' Sensitivity to Facial Expressions

We examined 6‐month‐old infants' abilities to discriminate smiling and frowning from neutral stimuli. In addition, we assessed the relationship between infants' preferences for varying intensities of smiling and frowning facial expressions and their mothers' history of depressive symptoms. Forty‐six infants were presented pairs of facial expressions, and their preferential looking time was recorded. They also participated in a 3‐min interaction with their mothers for which duration of both mother and infant gazing and smiling were coded. Analyses revealed that the infants reliably discriminated between varying intensities of smiling and frowning facial expressions and a paired neutral expression. In addition, infants' preferences for smiling and frowning expressions were related to self‐reports of maternal depressive symptoms experienced since the birth of the infant. Potential implications for social cognitive development are discussed.     

Discrimination of Large and Small Numerosities by Human Infants

Six experiments investigated infants' sensitivity to numerosity in auditory sequences. In prior studies (Lipton & Spelke, 2003), 6‐month‐old infants discriminated sequences of 8 versus 16 but not 8 versus 12 sounds, and 9‐month‐old infants discriminated 8 versus 12 but not 8 versus 10 sounds, when the continuous variables of rate, sound duration, and sequence duration were controlled. The current studies investigated whether infants' numerical discrimination is subject to the signature ratio limit of adults' numerosity discrimination. Four experiments at 6 and 9 months provided evidence for this signature limit, suggesting that common mechanisms underlie numerosity discrimination in infants and adults. In further experiments, infants failed to discriminate 2 versus 4 or 2 versus 3 sounds when tested under the same conditions as with large numbers. These findings accord with studies using visual‐spatial arrays (e.g., Clearfield & Mix, 1999) and suggest that separate systems underlie infants' representation of small and large numerosities.