Effects of Maternal Responsiveness on Infant Responsiveness and Behavior in the Still‐Face Task

The effects of maternal responsiveness on infant responsiveness and behavior in the Still‐Face Task were longitudinally examined through infants' first 3 months. Maternal vocal responsiveness and infant vocal and smiling responsiveness significantly increased when infants were 2 months of age. Mothers showed continuity of individual differences in vocal responsiveness from the infants' newborn period. Maternal responsiveness predicted infant responsiveness within and across sessions. Compared with infants with low‐responsive mothers, infants with high‐responsive mothers were more attentive and affectively engaged during the Still‐Face Task from 1 month of age. Infants with high‐responsive mothers discriminated between the task phases with their smiling at 1 month, a month before infants with low‐responsive mothers did so. Infants in both groups discriminated between the phases with their attention and nondistress vocalizations throughout their first 3 months. Results suggest that maternal responsiveness influences infant responsiveness and facilitates infants' engagement and expectations for social interaction.     

Using Object Knowledge in Visual Tracking and Reaching

Nine‐month‐old infants were presented with an engaging and challenging task of visually tracking and reaching for a rolling ball that disappeared and reappeared from behind an occluder. On some trials, the infant observed the experimenter place a barrier on the ball's track; the barrier remained partially visible above the occluder throughout the remainder of the trial. When the task involved only predictive tracking, infants' anticipatory gaze shifts were faster when no barrier was present. When the task involved both tracking and reaching, there were more reaches when no barrier was present. If the infant reached, the timing and extension of the reach and the accompanying gaze shift did not differ with regard to the barrier. Because catching the ball was quite difficult for these infants, task demands interfered with the integration of visual information and visuospatial reasoning about the barrier with the reaching action.     

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.     

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.     

Infants' Behavioral Strategies for Emotion Regulation With Fathers and Mothers: Associations With Emotional Expressions and Attachment Quality

This study examined 12‐ and 13‐month‐old infants' behavioral strategies for emotion regulation, emotional expressions, regulatory styles, and attachment quality with fathers and mothers. Eighty‐five infants participated in the Strange Situation procedure to assess attachment quality with mothers and fathers. Infants' behavioral strategies for emotion regulation were examined with each parent during a competing demands task. Emotion regulation styles were meaningfully related to infant‐father attachment quality. Although expressions of distress and positive affect were not consistent across mothers and fathers, there was consistency in infant strategy use, emotion regulation style, and attachment quality with mothers and fathers. Furthermore, infants who were securely attached to both parents showed greater consistency in parent‐oriented strategies than infants who were insecurely attached to one or both parents. Limitations of this study include the constrained laboratory setting, potential carryover effects, and a homogeneous, middle‐class sample.     

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.     

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.     

Avoidance of Heights on the Visual Cliff in Newly Walking Infants

Work with infants on the “visual cliff” links avoidance of drop‐offs to experience with self‐produced locomotion. Adolph's (2002) research on infants' perception of slope and gap traversability suggests that learning to avoid falling down is highly specific to the postural context in which it occurs. Infants, for example, who have learned to avoid crossing risky slopes while crawling must learn anew such avoidance when they start walking. Do newly walking infants avoid crossing the drop‐off of the visual cliff? Twenty prewalking but experienced crawling infants were compared with 20 similarly aged newly walking infants on their reactions to the visual cliff. Newly walking infants avoided moving onto the cliff's deep side even more consistently than did the prewalking crawlers. Thus, in the context of drop‐offs in visual texture, our results show that once avoidance of drop‐offs is established under conditions of crawling, it is developmentally maintained once infants begin walking.     

Common Coding of Observation and Execution of Action in 9‐Month‐Old Infants

Do 9‐month‐old infants motorically simulate actions they perceive others perform? Two experiments tested whether action observation, like overt reaching, is sufficient to elicit the Piagetian A‐not‐B error. Infants recovered a toy hidden at location A or observed an experimenter recover the toy. After the toy was hidden at location B, infants in both conditions perseverated in reaching to A, demonstrating that active search by the infant is not necessary for the A‐not‐B error. Consistent with prior research, infants displayed an ipsilateral bias when reaching, the so‐called mysterious midline barrier. A similar ipsilateral bias was also observed depending on the manner in which the experimenter reached; infants perseverated following observation of ipsi‐ but not contralateral reaches by the experimenter. Thus, infants perseverated only following observation of actions they themselves were able to perform, suggesting that they coded others' actions in terms of motor simulation.     

Emotion Regulation Via Maternal Touch

The study of emotion elicitation in the caregiver‐infant dyad has focused almost exclusively on the facial and vocal channels, whereas little attention has been given to the contribution of the tactile channel. This study was undertaken to investigate the effects of touch on infants' emotions. During the time that objects were presented to the dyad, mothers provided tactile stimulation to their 12‐month‐old infants by either (a) tensing their fingers around the infants' abdomen while abruptly inhaling, (b) relaxing their grip around the infants' abdomen, or (c) not providing additional tactile stimulation (control condition). The results revealed that infants in the first condition (a) touched the objects less and waited longer to touch the objects while displaying more negative emotional displays compared to infants in the control condition. However, no apparent differences were found between infants in the second condition (b) and the control condition. The results suggest that infants' emotions may be elicited by specific parameters of touch.     

Temperamental Susceptibility to Parenting among Preterm and Full‐Term Infants in Early Cognitive Development

The current study examined the interaction between premature birth, temperamental reactivity, and parenting in early cognitive development. Participants were 142 infants (80 preterm; 62 full term) and their parents. Parent–child interactions (maternal, paternal, and co‐parental) were observed at age 6 months to assess parental structuring behaviors. Additionally, both parents reported on infants' temperamental reactivity. At 12 months of age, infants' cognitive abilities were assessed. Consistent with the diathesis–stress model, preterm infants had lower cognitive outcomes than full‐term infants when exposed to low levels of co‐parental structuring, but functioned similarly when exposed to high levels of co‐parental structuring. However, temperamental reactivity moderated this effect: Infants who carried one susceptibility factor (i.e., premature birth or reactive temperament) were similarly affected by co‐parental structuring, whereas infants who carried two or no susceptibility factors were not. Furthermore, consistent with the differential susceptibility hypothesis, infants with highly reactive temperaments had lower cognitive functioning when exposed to low maternal structuring, but higher cognitive functioning when exposed to high maternal structuring compared to infants with lower reactivity. Results from this study highlight the importance of considering both temperamental reactivity and quality of parenting in understanding preterm infants' early cognitive vulnerability.     

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.     

Infant Brain Responses to Object Weight: Exploring Goal‐Directed Actions and Self‐Experience

Recent work has suggested the value of electroencephalographic (EEG) measures in the study of infants' processing of human action. Studies in this area have investigated desynchronization of the sensorimotor mu rhythm during action execution and action observation in infancy. Untested but critical to theory is whether the mu rhythm shows a differential response to actions which share similar goals but have different motor requirements or sensory outcomes. By varying the invisible property of object weight, we controlled for the abstract goal (reach, grasp, and lift the object), while allowing other aspects of the action to vary. The mu response during 14‐month‐old infants' own executed actions showed a differential hemispheric response between acting on heavier and lighter objects. EEG responses also showed sensitivity to “expected object weight” when infants simply observed an experimenter reach for objects that the infants' prior experience indicated were heavier vs. lighter. Crucially, this neural reactivity was predictive—during the observation of the other reaching toward the object, before lifting occurred. This suggests that infants' own self‐experience with a particular object's weight influences their processing of others' actions on the object, with implications for developmental social‐cognitive neuroscience.     

Infant Affect During Parent—Infant Interaction at 3 and 6 Months: Differences Between Mothers and Fathers and Influence of Parent History of Depression

Fifty families participated in mother‐infant and father‐infant still‐face interaction at infant ages 3 and 6 months as part of a study of affect in early parent‐infant relationships. Infants' positive and negative affect and parents' positive affect and physical play were coded from videotapes. Consistent with previous research, during the normal condition, mothers displayed more positive affect than did fathers, and fathers were more likely than mothers to display physical play. Infants were more positive with mothers than with fathers. Parents' positive affect but not parent gender predicted infants' positive affect at 6 months. During the still‐face condition, infants of parents with a lifetime history of depression were more likely to display negative affect and less likely to display positive affect than infants with no such parent history. Infants' affect was unrelated to parents' current level of depressive symptoms, which indicates the value of considering family history of psychopathology when examining individual differences in infants' affect.     

Modeling Infant Speech Sound Discrimination Using Simple Associative Networks

Infants' responses in speech sound discrimination tasks can be nonmonotonic over time. Stager and Werker (1997) reported such data in a bimodal habituation task. In this task, 8‐month‐old infants were capable of discriminations that involved minimal contrast pairs, whereas 14‐month‐old infants were not It was argued that the older infants' attenuated performance was linked to their processing of the stimuli for meaning. The authors suggested that these data are diagnostic of a qualitative shift in infant cognition. We describe an associative connectionist model showing a similar decrement in discrimination without any qualitative shift in processing. The model suggests that responses to phonemic contrasts may be a nonmonotonic function of experience with language. The implications of this idea are discussed. The model also provides a formal framework fer studying habituation‐dishabituation behaviors in infancy.     

Acoustic Packaging of Action Sequences by Infants

This study investigated whether acoustic input, in the form of infant‐directed speech, influenced infants' segmenting of action sequences. Thirty‐two 7.5‐ to 11.5‐month‐old infants were familiarized with video sequences made up of short action clips. Narration coincided with portions of the action stream to package certain pairs of clips together. At test, packaged and nonpackaged pairs of actions were presented side by side in silence. Narration heard during familiarization influenced how infants viewed the action units, such that at test, infants older than 9.5 months (but not younger) looked longer at the nonpackaged than the packaged action sequences. The role of infant‐directed speech as well as other types of acoustic input in assisting infants' processing of action is discussed.     

Infants' Ability to Learn Phonetically Similar Words: Effects of Age and Vocabulary Size

What do novice word learners know about the sound of words? Word‐learning tasks suggest that young infants (14 months old) confuse similar‐sounding words, whereas mispronunciation detection tasks suggest that slightly older infants (18–24 months old) correctly distinguish similar words. Here we explore whether the difficulty at 14 months stems from infants' novice status as word learners or whether it is inherent in the task demands of learning new words. Results from 3 experiments support a developmental explanation. In Experiment 1, infants of 20 months learned to pair 2 phonetically similar words to 2 different objects under precisely the same conditions that infants of 14 months (Experiment 2) failed. In Experiment 3, infants of 17 months showed intermediate, but still successful, performance in the task. Vocabulary size predicted word‐learning performance, but only in the younger, less experienced word learners. The implications of these results for theories of word learning and lexical representation are discussed.     

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.     

Seven‐Month‐Old Infants Selectively Reproduce the Goals of Animate But Not Inanimate Agents

We tested 7‐month‐old infants' sensitivity to others' goals in an imitation task, and assessed whether infants are as likely to imitate the goals of nonhuman agents as they are to imitate human goals. In the current studies, we used the paradigm developed by Hamlin et. al (in press) to test infants' responses to human actions versus closely matched inanimate object motions. The experimental events resembled those from Luo and Baillargeon's (2005) looking‐time study in which infants responded to the movements of an inanimate object (a self‐propelled box) as goal‐directed. Although infants responded visually to the goal structure of the object's movement, here they did not reproduce the box's goal. These results provide further evidence that 7‐month‐olds' goal representations are sufficiently robust to drive their own manual actions. However, they indicate that infants' responses to inanimate object movements may not be robust in this way.     

Evidence of Early Strategies in Learning to Walk

Learning to walk is a dynamic process requiring the fine coordination, assembly, and balancing of many body segments at once. For the young walker, coordinating all these behavioral levels may be quite daunting. In this study, we examine the whole‐body strategies to which infants resort to produce their first independent steps and progress over the first months of walking experience. Six infants were followed weekly from the onset of independent upright locomotion for 8 weeks, and then every other week until 4 months of walking experience. The walking kinematics from the infants' earliest steps were cluster‐analyzed and the infants were classified into 3 groups. Follow‐up comparisons with kinematics recordings were used to quantify the infants' strategies more precisely and track how these early forms of walking evolved over time. Results revealed that in the first weeks of independent walking, 3 infants used a stepping strategy, 1 used a twisting strategy, and 2 used a falling strategy to move their body forward and perform their first unsupported steps. As the infants gained walking experience, their walking patterns became more similar. These findings indicate that infants discover different solutions to use their body and control their balance when beginning to walk. With time, infants adopt a more efficient solution that incorporates and integrates elements of the different strategies.