Stress changes the representational landscape: evidence from word segmentation

Over the past couple of decades, research has established that infants are sensitive to the predominant stress pattern of their native language. However, the degree to which the stress pattern shapes infants' language development has yet to be fully determined. Whether stress is merely a cue to help organize the patterns of speech or whether it is an important part of the representation of speech sound sequences has still to be explored. Building on research in the areas of infant speech perception and segmentation, we asked how several months of exposure to the target language shapes infants' speech processing biases with respect to lexical stress. We hypothesize that infants represent stressed and unstressed syllables differently, and employed analyses of child-directed speech to show how this change to the representational landscape results in better distribution-based word segmentation as well as an advantage for stress-initial syllable sequences. A series of experiments then tested 9- and 7-month-old infants on their ability to use lexical stress without any other cues present to parse sequences from an artificial language. We found that infants adopted a stress-initial syllable strategy and that they appear to encode stress information as part of their proto-lexical representations. Together, the results of these studies suggest that stress information in the ambient language not only shapes how statistics are calculated over the speech input, but that it is also encoded in the representations of parsed speech sequences.     

Action experience alters 3-month-old infants' perception of others' actions

An intervention facilitated 3-month-old infants' apprehension of objects either prior to (reach first), or after (watch first) viewing another person grasp similar objects in a visual habituation procedure. Action experience facilitated action perception: reach-first infants focused on the relation between the actor and her goal, but watch-first infants did not. Infants' sensitivity to the actor's goal was correlated with their engagement in object-directed contact with the toys. These findings indicate that infants can rapidly form goal-based action representations and suggest a developmental link between infants' goal directed actions and their ability to detect goals in the actions of others.     

Infant temperament and maternal sensitivity behavior in the first year of life

Maternal sensitivity behavior (MSB) and infant temperament were investigated among 56 Finnish low-risk mothers and their full-term and healthy infants. The mothers were from families with good economic status, the infant's parents lived together, and the mothers were well educated. Mothers and infants were video-recorded in free-play situations at home, and evaluated using the Parent-Child Early Relational Assessment Scale (PCERA). The infants were also assessed using the Revised Infant Temperament Questionnaire (R-ITQ) and the Toddler Temperament Questionnaire (TTQ). Most of the temperament characteristics showed moderate stability during the first year. MSB was related to infant temperament characteristics at 3, 6 and 12 months of age. Gender differences in temperament were evident already at 6 and 12 months of age. Few prior studies have reported gender differences in infancy.     

Reasoning about a hidden object after a delay: evidence for robust representations in 5-month-old infants

The present research examined two alternative interpretations of violation-of-expectation findings that young infants can represent hidden objects. One interpretation is that, when watching an event in which an object becomes hidden behind another object, infants form a prediction about the event's outcome while both objects are still visible, and then check whether this prediction was accurate. The other interpretation is that infants' initial representations of hidden objects are weak and short-lived and as such sufficient for success in most violation-of-expectation tasks (as objects are typically hidden for only a few seconds at a time), but not more challenging tasks. Five-month-old infants succeeded in reasoning about the interaction of a visible and a hidden object even though (1) the two objects were never simultaneously visible, and (2) a 3- or 4-min delay preceded the test trials. These results provide evidence for robust representations of hidden objects in young infants.     

Effects of multilingualism on Australian infants’ language environments in early childhood education centers

This study investigates differences in the language environments experienced by multilingual and monolingual infants in early childhood education and care (ECEC) settings. The Language Environment Analysis (LENA) technology was used to collect day-long audio-recordings from 181 one-year-old infants (age range from 12 to 21 months). We examined whether infants’ multilingual status predicts the amount of educators’ language input (adult word count, AWC), child vocalizations (CVC) and conversational turns (CTC), as well as interaction effects on AWC, CVC and CTC of infants’ multilingual status and other infant, home and ECEC characteristics. Multilevel mixed effects models revealed no main effect of infants’ multilingual status on the language environment outcome variables. Instead, infant gender significantly predicted adult word count, with female infants hearing more words from educators than male infants. There was a significant interaction effect between the infants’ multilingual status and both their age and length of time in an ECEC setting on child vocalizations. While monolingual infants produced more vocalizations as their age increased, multilingual infants did not show this increase in vocalizations with age. Further, the difference between monolingual and multilingual children’s vocalizations decreased as the length of time in ECEC increased. There were no significant predictors of conversational turns. Findings from this study suggest that early childhood educators do not adjust their talk according to the multilingual status of the infants. However, multilingual infants do not increase their vocalizations as their age increases to the same extent as do their monolingual peers. The interaction effect between multilingualism and the length of ECEC attendance also implies that ECEC environments may be particularly beneficial for supporting multilingual infants’ vocalizations. This study highlights the need to provide pedagogical support to educators to help them to encourage multilingual infants’ vocalizations in ECEC settings.     

Association between Hyperemesis Gravidarum in pregnancy on postnatal ability of infants to attend to a play task with their mother

Research indicates a higher prevalence of attention deficits in children exposed to HG in utero compared to controls with some claiming that the deficit is due to prenatal effects of malnutrition in HG mothers and others that it is due to maternal mental health after birth. The current study examines the effect of hyperemesis gravidarum (HG) diagnosis during pregnancy on infant attention controlling for maternal stress, depression anxiety and attachment. Thirty-eight infants mean age 4 months were videotaped with their mothers (19 mothers with a hyperemesis diagnosis and 19 controls) during play with a soft toy and looking at a picture book. Infant attention was operationalized as gaze direction towards the play activity, mother, and ‘distracted’ (indicated by looking away from play or mother). Mothers completed stress, depression, anxiety, and attachment questionnaires. HG exposed infants attended for significantly less time during play with a book or soft toy compared to controls. Maternal stress, depression, anxiety, and attachment did not differ in HG mothers and controls. Infant ability to attend to the toy, book, mother or being distracted did not relate to maternal postnatal attachment, or mental health. These results suggest that the prenatal environment, especially exposure to HG might be associated with reduced infant attention abilities independent of maternal postnatal health.     

Neurophysiology of sustained attention in early infancy: Investigating longitudinal relations with recognition memory outcomes

The ability to sustain attention is a critical cognitive domain that emerges in infancy and is predictive of a multitude of cognitive processes. Here, we used a heart rate (HR) defined measure of sustained attention to assess corresponding changes in frontal electroencephalography (EEG) power at 3 months of age. Second, we examined how the neural underpinnings of HR-defined sustained attention were associated with sustained attention engagement. Third, we evaluated if neural or behavioral sustained attention measures at 3-months predicted subsequent recognition memory scores at 9 months of age. Seventy-five infants were included at 3 months of age and provided usable attention and EEG data and 25 infants returned to the lab at 9 months and provided usable recognition memory data. The current study focuses on oscillatory power in the theta (4–6 Hz) frequency band during phases of HR-defined sustained attention and inattention phases. Results revealed that theta power was significantly higher during phases of sustained attention. Second, higher theta power during sustained attention was positively associated with proportion of time in sustained attention. Third, longitudinal analyses indicated a significant positive association between theta power during sustained attention on 9-month visual paired comparison scores such that higher theta power predicted higher visual paired comparison scores at 9-months. These results highlight the interrelation of the attention and arousal systems which have longitudinal implications for subsequent recognition memory processes.     

Stability of maternal postnatal bonding between 3 and 6 months: Associations with maternal mental health and infant temperament

Maternal bonding is key for infant development and well-being. Research to date focused on prenatal bonding experience, with fewer studies looking at the postnatal period. Moreover, evidence suggests significant associations among maternal bonding, maternal mental health, and infant temperament. The joint impact of maternal mental health and infant temperament on maternal postnatal bonding remains unclear, with limited research reporting longitudinal data. Hence, the present study aims (1) to explore the impact of maternal mental health and infant temperament on postnatal bonding at both 3 and 6 months of age, (2) to explore postnatal bonding stability from 3 to 6 months, and (3) to determine which factors are linked with 3-to-6-month changes in bonding. At the infants' 3 months (n = 261) and 6 months of age (n = 217), mothers provided measures of bonding, depressive and anxious symptoms, and infant temperament via validated questionnaires. At 3 months, higher levels of maternal bonding were predicted by lower levels of anxiety and depression in the mothers and by higher infants' regulation scores. At 6 months, lower levels of anxiety and depression predicted higher levels of bonding. Moreover, mothers showing decreases in bonding were characterized by 3-to-6-month increases in depression and anxiety, as well as increased reported difficulties in regulation dimensions of infant temperament. This study highlights the impact of both maternal mental health and infant temperament on maternal postnatal bonding in a longitudinal sample and could offer useful information for early childhood prevention and care.     

Effects of massage intervention on discharged premature infants’ weight,parental stress,and parent–child attachment: A randomized controlled trial

Infant massage enhances the growth and development of premature infants and promotes parent–child bonding. However, its effects on parental stress and parent–child attachment in premature infants, as well as gender differences thereof, remain unclear. In this randomized controlled trial, we used a repeated-measures design and included 61 premature infants (mean gestational age: 35.1 ± 1.5 weeks). Weight, parental stress, and parent–child attachment were measured at multiple time points: before massage and 1, 4, 8, and 12 weeks after commencing infant massage. The results revealed that the massage group infants had significantly higher weight gain than the control (no massage) group infants at all four time points. Moreover, parents in the massage group reported notably lower levels of stress than those in the control group, particularly in the parental distress and difficult children subscales. No significant between-group differences were observed in parent–child attachment. Furthermore, no significant differences were observed between fathers and mothers in parental stress and parent–child attachment. However, fathers reported higher levels of distress than mothers at 4 and 12 weeks. In conclusion, infant massage led to increased infant weight and reduced parental stress over time, and differences between fathers and mothers were not significant, except fathers exhibiting higher levels of distress than mothers over time. Healthcare professionals should educate and support parents on infant massage before discharge of premature infants.     

Maternal psychological functioning mediates the association between infant behavior and subsequent child psychological functioning

Symptoms of psychopathology that onset during childhood are often more severe, chronic, and difficult to treat than symptoms that first appear later in life. Maternal psychological symptoms are associated with the development of psychological symptoms in children. However, less research focuses on whether children’s behaviors may presage maternal psychological difficulties that, in turn, contribute to the child’s own psychological functioning. Identifying psychological difficulties in families and intervening in early life may lower risk for intergenerational transmission of subsequent psychological symptoms. Even at non-clinical or normative levels, exploring transactional models of parent-child behavior and psychological functioning may provide insight into the development of later psychological difficulties or symptoms within families. Thus, the current study examined whether difficult infant behavior (e.g., fussiness, unpredictability) is associated with future maternal psychological difficulties and subsequently, the child’s own psychological functioning in early childhood. The current sample includes 847 dyads from a multi-wave birth cohort in England (‘Born in Bradford’), who identified as predominantly non-White (62.2%) and socioeconomically diverse. Mothers reported on their child’s behaviors at 6 months, their own psychological functioning during pregnancy and at 18 months postpartum, and their child’s psychological functioning at age 3. Results of a mediation model revealed that the association between infant behavior at 6 months and child psychological functioning at 3 years is partially explained by maternal psychological functioning at 18 months, even after accounting for psychological difficulties during pregnancy, maternal age at birth, child sex, family income, and ethnicity. Post-hoc exploratory analyses revealed that the association between infant behavior, maternal psychological functioning, and subsequent child psychological functioning was significant for Pakistani British families but not White British families. These findings provide preliminary evidence that infant behaviors (e.g., temperament) may presage future maternal psychological difficulties and subsequent child psychological functioning, above and beyond previous maternal psychological functioning. Importantly, these results highlight infant behavior as a potential catalyst for later psychological difficulties within families.