Contingency Learning and Reactivity in Preterm and Full‐Term Infants at 3 Months

Learning difficulties in preterm infants are thought to reflect impairment in arousal regulation. We examined relationships among gestational age, learning speed, and behavioral and physiological reactivity in 55 preterm and 49 full‐term infants during baseline, contingency, and nonreinforcement phases of a conjugate mobile paradigm at 3 months corrected age. For all infants, negative affect, looking duration, and heart rate levels increased during contingency and nonreinforcement phases, whereas respiratory sinus arrhythmia (RSA, an index of parasympathetic activity) decreased and Cortisol did not change. Learners showed greater RSA suppression and less negative affect than nonleamers. This pattern was particularly evident in the preterm group. Overall, preterm infants showed less learning, spent less time looking at the mobile, and had lower Cortisol levels than full‐term infants. Preterm infants also showed greater heart rate responses to contingency and dampened heart rate responses to nonreinforcement compared to full‐term infants. Findings underscore differences in basal and reactivity measures in preterm compared to full‐term infants and suggest that the capacity to regulate parasympathetic activity during a challenge enhances learning in preterm infants.     

Sensitivity to Social Contingency From Mothers and Strangers in 2‐, 4‐, and 6‐Month‐Old Infants

Infants' sensitivity to changes in social contingency was investigated by presenting 2‐, 4‐, and 6‐month‐old infants with 3 episodes of social interaction from mothers and strangers: 2 contingent interactions and 1 noncontingent replay. Three orders were presented: (a) contingent, noncontingent, contingent; (b) contingent, contingent, noncontingent; and (c) noncontingent, contingent, contingent. Contingency and carryover effects were shown to both mothers and strangers in the different orders of presentation. Infants were more visually attentive to contingent interactions than to the noncontingent replay when contingent interactions occurred prior to the replay, and the infants' level of attention to the noncontingent replay carried over to subsequent contingent interactions. The 4‐ and 6‐month‐old infants showed contingency and carryover effects by their visual attention and smiling. Examination of effect sizes for attention suggests 2‐month‐old infants may be beginning to show the effects. Reasons for age changes in sensitivity to social contingency are discussed.     

Sensitivity to Social Contingency and Positive Emotion in 2‐Month‐Olds

This study was aimed at sorting out conflicting results in the literature concerning 2‐month‐olds' sensitivity to interpersonal contingency, and investigated the potential role of infants' positive emotion in contingency detection. Infants were randomly assigned to an experimental group (EG) that was presented an uninterrupted live–replay–live sequence of three 30‐sec episodes of their mothers' communicative behavior using a double video TV paradigm, or to a control group (CG) that was presented an uninterrupted 90 sec of contingent maternal interactions. Infants of the EG grimaced more than infants of the CG only during the 2nd period of social exchange (replay vs. 2nd live period), but there was an increase of grimacing and a reduction in gazing during the 3rd period of televised interactions in infants of the CG. Each group was split into 2 subgroups a posteriori according to the presence or absence of smiling during the 1st contingent episode. Smiling infants of the EG reacted more negatively during the 2nd interaction period compared to other subgroups. These findings support the view that sensitivity, not fatigue or loss of interest to maternal stimulation, accounts for 2‐month‐olds' expressive changes during noncontingent maternal interactions; fatigue or loss of interest better explains the decline in attention and the increase of negative expressiveness during the last period of contingent interaction. The findings also suggest that the emotional climate of dyadic exchanges could be a contributing factor to infants' ability to detect the relations between their own actions and those of their social partners.     

Individual Differences in the Contribution of Maternal Soothing to Infant Distress Reduction

This study investigates individual differences in the contribution of specific maternal regulatory behaviors to the mother‐infant dyad's regulation of infant distress response. Additionally, we examined the stability of infants' stress responses and the stability of specific maternal soothing behaviors. The sample included 128 mother‐infant dyads that were observed during an inoculation at 2 and 6 months. The average intensity of infant cry response showed modest stability across age only before controlling for the infant's general state of irritability, and the duration of crying was not stable. Of the 8 specific maternal regulatory behaviors studied, affection, touching, and vocalizing showed the strongest stability across infant age. Finally, an index of the contingency between maternal soothing and infant cry reduction at 2 months predicted shorter cry duration but not cry intensity at 6 months. The results of this study indicate that infants whose mothers showed a greater contribution to reducing their distress at 2 months showed a shorter duration of crying 4 months later. This suggests a possible longitudinal influence of maternal regulation on infants' distress responses.     

ACKNOWLEDGMENT OF GUEST REVIEWERS

Two‐month‐old infants (N = 29) participated in face‐to‐face interactions with their mothers and with strangers. The contingent responsiveness for smiles and vocalizations, while attending to the partner, was assessed for each partner in both interactions. For smiles and for vocalizations, infants were less responsive to the stranger relative to the mother when the stranger's contingent responsiveness was either more contingent or less contingent than that of the mother. Results are supportive of the hypothesis that young infants develop sensitivities to levels of social contingency present in their maternal interactions, which influence their responsiveness to others.     

Urgent engagement in 9/11 pregnant widows and their infants: Transmission of trauma

The potential effects of maternal trauma on mother–infant interaction remain insufficiently studied empirically. This study examined the effects of the September 11, 2001, trauma on mother–infant interaction in mothers who were pregnant and widowed on 9/11, and their infants aged 4–6 months. Split‐screen videotaped interaction was coded on a one‐second basis for infant gaze, facial affect, and vocal affect; and mother gaze, facial affect, and touch. We examined the temporal dynamics of communication: self‐contingency and interactive contingency of behavior by time‐series methods. We documented heightened maternal and infant efforts at engagement in the 9/11 (vs. control) dyads. Both partners had difficulty tolerating moments of looking away as well as moments of negative behavior patterns. Heightened efforts to maintain a positive visual engagement may be adaptive and a potential source of resilience, but these patterns may also carry risk: working too hard to make it work. A vigilant, hyper‐contingent, high‐arousal engagement was the central mode of the interpersonal transmission of the trauma to these infants, with implications for intervention.     

Effects of Contingent Reinforcement of Actions on Infants' Object‐Directed Reaching

The role of contingency learning was examined in 3‐month‐old infants' reaching movements. Infants in the experimental group experienced 9 min of active training during which they could move their arms in a reach‐like fashion to pull and move a mobile. Infants in the control group experienced 9 min of passive training during which they watched a mobile move. Prior to (pre‐training) and following the mobile experience (post‐training), infants in both conditions were given an opportunity to interact with a rattle placed within and out of their reach. Compared with infants in the control condition, infants in the experimental condition produced reach‐like movements more frequently during the mobile experience; they also showed a greater increase in reaching attempts from pre‐ to post‐training assessments with the rattle. These findings show that reinforcement of arm extensions and retractions increases the frequency of infants' reaching behaviors. This result suggests that the reinforcement of components of infants' behaviors may contribute to the successful assembly of these behaviors. This process could help keep infants engaged during the lengthy transition from prereaching to independent reaching.     

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.     

Neurobehavioral Consequences of Prenatal Exposure to Smoking at 6 to 8 Months of Age

Between 400,000 and 800,000 infants are born in the United States each year to women who smoked cigarettes during their pregnancy. Whereas the physical health consequences to infants of prenatal exposure to smoking are well established, the early neurobehavioral consequences are less well understood. This study investigated the neurobehavioral consequences of prenatal exposure to smoking using an epidemiologically derived sample of 454 infants who were drawn from a larger sample of 1,292 infants whose families were recruited at birth. Results indicated that, on average, infants who were exposed to higher levels of prenatal smoking exhibited less positive affect and greater irritability. Moreover, among male infants, elevated levels of prenatal exposure to smoking were associated with lower levels of approach, gross motor movement, reactivity, and attention. There was no evidence that the effects of prenatal exposure to smoking on infant neurobehavioral functioning were mediated by physical growth parameters (infant weight and head circumference) that are also known to be affected by prenatal exposure to smoking.     

Predicting Patterns of Regulatory Behavior in the Still‐Face Paradigm at 3 Months

The current study addressed two aims: (1) to describe different patterns of infant regulatory behavior during the Face‐to‐Face Still‐Face (FFSF) paradigm at 3 months of age and (2) to identify specific, independent predictors of these patterns from an a priori set of demographic, infant (e.g., temperament), and maternal (e.g., sensitivity) variables. Analyses were based on data collected for 121 mother–infant dyads assessed longitudinally in the newborn period and again at 3 months. In the newborn period, infants’ neurobehavior was evaluated using the Neonatal Behavioral Assessment Scale (NBAS) and mothers reported on their caregiving confidence and their newborns’ irritability and alertness. At 3 months, mothers reported on their infant's temperament, and mother–infant interactions were videotaped during free play and the FFSF. Three patterns of infant regulatory behavior were observed. The most common was a Social‐Positive Oriented Pattern, followed by a Distressed‐Inconsolable Pattern, and a Self‐Comfort Oriented Pattern. Results of multinomial logistic regression indicated that categorical assignment was not associated with demographic or infant characteristics, but rather with dyadic regulatory processes in which maternal reparatory sensitivity played a crucial role.     

Modeling Age Differences in Infant Category Learning

We used an encoder version of cascade correlation to simulate Younger and Cohen's (1983, 1986) finding that 10‐month‐olds recover attention on the basis of correlations among stimulus features, but 4‐ and 7‐month‐olds recover attention on the basis of stimulus features. We captured these effects by varying the score threshold parameter in cascade correlation, which controls how deeply training patterns are learned. When networks learned deeply, they showed more error to uncorrelated than to correlated test patterns, indicating that they abstracted correlations during familiarization. When prevented from learning deeply, networks decreased error during familiarization and showed as much error to correlated as to uncorrelated tests but less than to test items with novel features, indicating that they learned features but not correlations among features. Our explanation is that older infants learn more from the same exposure than do younger infants. Unlike previous explanations that postulate unspecified qualitative shifts in processing with age, our explanation focuses on quantitatively deeper learning with increasing age. Finally, we provide some new empirical evidence to support this explanation.     

Physiological and Emotional Reactivity to Learning and Frustration

This study examined the behavioral (arm, facial) and autonomic (heart rate, respiratory sinus arrhythmia [RSA], and adrenocortical axis) reactivity of 56 4‐month‐old infants in response to contingency learning and extinction‐induced frustration. During learning, infants displayed increases in operant arm response and positive emotional expressions. Changes in average RSA(V_NA) paralleled the observed changes in facial expressions in general and maintained an inverse relation with heart rate throughout most of the session. When frustrated by extinction, infants displayed increases in negative expressions, heart rate, and a brief increase in RSA(V_NA) followed by a significant decrease. No significant changes were observed for Cortisol. These behavioral and facial responses are consistent with earlier work. The physiological changes, along with the facial expressions and instrumental responses, indicate that the autonomic nervous system functions as a coordinated affect system by 4 months of age.     

The Developmental Course of Habituation in Infancy and Preschool Outcome

A longitudinal sample of 226 infants were tested monthly on habituation and novelty preference tasks, augmented with simultaneous heart rate recording from 3 to 9 months of age. Infants were then administered the Bayley Scales of Infant Development II (BSID) and MacArthur Communicative Development Inventory (MCDI) at 12, 18, and 24 months. Prior findings regarding the decline in look duration with age were replicated. Age‐based factors were extracted from the monthly assessments, an early attention factor from 3 to 6 months and a late attention factor from 7 to 9 months. A novelty preference factor, which grouped recognition performance at 4 and 6 months of age, was also derived. The late attention factor correlated negatively with a factor score derived from the BSID mental index, and the novelty preference aggregate was correlated positively with a factor score derived from the MCDI production scores. Two clusters of infants were derived based on the developmental course of change from the early attention to late attention look duration aggregates: One cluster (n= 150) decreased strongly, and another (n= 50) increased. Infants belonging to these clusters subsequently differed on both the BSID and MCDI outcomes, with the former cluster showing distinct advantages that increased as the outcome assessments progressed from 12 to 24 months of age. This finding was bolstered by subsequent analyses of data from infants who completed all tests run from 3 to 9 months. The results of this study suggest that the developmental course of attention during infancy is an important clue to cognitive and language outcomes in early childhood.     

Young Infants Match Facial and Vocal Emotional Expressions of Other Infants

Research has demonstrated that infants recognize emotional expressions of adults in the first half year of life. We extended this research to a new domain, infant perception of the expressions of other infants. In an intermodal matching procedure, 3.5‐ and 5‐month‐old infants heard a series of infant vocal expressions (positive and negative affect) along with side‐by‐side dynamic videos in which one infant conveyed positive facial affect and another infant conveyed negative facial affect. Results demonstrated that 5‐month‐olds matched the vocal expressions with the affectively congruent facial expressions, whereas 3.5‐month‐olds showed no evidence of matching. These findings indicate that by 5 months of age, infants detect, discriminate, and match the facial and vocal affective displays of other infants. Further, because the facial and vocal expressions were portrayed by different infants and shared no face–voice synchrony, temporal, or intensity patterning, matching was likely based on detection of a more general affective valence common to the face and voice.     

Infants' ERP Responses to Novel and Familiar Stimuli Change Over Time: Implications for Novelty Detection and Memory

Detection of novelty is an important cognitive ability early in development, when infants must learn a great deal about their world. Work with adults has identified networks of brain areas involved in novelty detection; this study investigated electrophysiological correlates of detection of novelty and recognition of familiarity in 9‐month‐old infants, using event‐related potentials (ERPs). Infants were familiarized with an event in the laboratory, then ERPs were recorded as they viewed repeated presentations of pictures of this familiar event and a novel event, along with single presentations of 30 trial‐unique events. A middle‐latency negative component was sensitive to degree of novelty, differing in amplitude and latency by stimulus condition and across repeated presentations. Long‐latency slow‐wave activity also related to stimulus condition. Findings have implications for our understanding of infants' detection of novel information and the processes that render the novel familiar.     

Young Infants Detect the Direction of Biological Motion in Point‐Light Displays

In the present study, we examined if young infants can extract information regarding the directionality of biological motion. We report that 6‐month‐old infants can differentiate leftward and rightward motions from a movie depicting the sagittal view of an upright human point‐light walker, walking as if on a treadmill. Inversion of the stimuli resulted in no detection of directionality. These findings suggest that biological motion displays convey information for young infants beyond that which distinguishes them from nonbiological motion; aspects of the action itself are also detected. The potential visual mechanisms underlying biological motion detection, as well as the behavioral interpretations of point‐light figures, are discussed.     

Attention during Visual Preference Tasks: Relation to Caregiving and Face Recognition

This research examined how caregiver experience (female primary caregiver or distributed caregiving with mom and dad) influenced 10‐, 14‐, and 16‐month‐olds’ visual preferences and attention toward internal facial features of female–male face pairs, and how these behaviors related to novelty preferences in a face recognition task and speed and accuracy on a visual search task. In the visual preference task, infants visually preferred male faces, regardless of caregiver experience. Despite similarities in visual preferences, infants’ attention toward females and males’ internal facial features was related for infants with distributed caregiving only. Infants’ performance across face processing tasks most often correlated for those with female primary caregivers. Results further our understanding of how infants with female primary caregivers display specialized processing of female faces, and how infants with distributed caregiving show similarities in their attention to female and male facial features.     

Individual Differences in Infants’ Joint Attention Behaviors With Mother and a New Social Partner

Relations between infant–mother attachment security at 15 months and infants’ (N = 206) joint attention behaviors (a) with an experimenter at 8 and 15 months, and (b) with their mothers at 15 months were investigated. No concurrent or longitudinal relations were observed between attachment security and infants’ tendency to respond to an experimenter’s bids for joint attention. Higher levels of initiating joint attention with an experimenter at 15 months were associated with insecure‐avoidant attachment. Insecure‐avoidant attachment was also associated with lower scores for initiating high‐level joint attention behaviors (pointing, showing, and giving) with the mother at age 15 months. The fact that security‐related differences in initiating joint attention with an experimenter were observed only once the attachment relationship was consolidated suggests that (a) attachment security may influence infants’ active engagement with new social partners, and (b) insecure‐avoidant infants may compensate for reduced social contact with the caregiver by initiating more interaction with other social partners.     

Infant Contingency/Extinction Performance After Observing Partial Reinforcement

Social information gathering by infants 6 and 12 months old was examined as a foundation for later social learning that may be uniquely human. Infant performance on a contingency/extinction task was studied following a caregiver demonstration of the contingency on varied reinforcement schedules. Infants who observed caregivers receive any reinforcing stimulation in pretraining decreased responding over their own acquisition period, possibly because they began to habituate to the reinforcer. In extinction, infants who observed caregivers receive partial reinforcement in pretraining were more persistent in responding than others. This suggested that direct experience with partial reinforcement is not needed for greater persistence in extinction. These studies revealed details of social learning in the 1st year.     

Olfactory Familiarization and Discrimination in Preterm and Full‐Term Newborns

The purpose of this study was to observe olfactory detection and discrimination in preterm and full‐term newborns. Infants were familiarized for 10 trials with either vanillin or anethole. On each trial, a cotton swab perfumed with one of the odors was slowly moved in front of the baby's nose for 10 sec. For half of the preterm and full‐term infants, a new odor was presented after the last familiarization trial (experimental groups). For the other half, the same odor as during familiarization was presented (control groups). Facial and head movements for both populations and heart rates for preterm infants were recorded before, during, and after odor presentation. Preterm infants reacted to the scents by increasing facial actions and heart rate but not head movements. Full‐term infants increased facial and head movements. Neither population showed a clear behavioral habituation pattern, but full‐term newborns had a significantly reduced facial reactivity on the last familiarization trial compared to preterm infants. Preterm newborns did, however, show cardiac habituation on the last familiarization trial. Preterm and full‐term infants presented with a new odor after familiarization increased responding compared to infants presented with the same odor, indicating their ability to discriminate between 2 odors. Infants' reactivity and discrimination to odors indicate preterm and full‐term newborns' ability to be attuned to their olfactory environment.