Infancy最新文献

To efficiently recognize words, children learning an intonational language like English should avoid interpreting pitch-contour variation as signaling lexical contrast, despite the relevance of pitch at other levels of structure. Thus far, the developmental time-course with which English-learning children rule out pitch as a contrastive feature has been incompletely characterized. Prior studies have tested diverse lexical contrasts and have not tested beyond 30 months. To specify the developmental trajectory over a broader age range, we extended a prior study (Quam & Swingley, 2010), in which 30-month-olds and adults disregarded pitch changes, but attended to vowel changes, in newly learned words. Using the same phonological contrasts, we tested 3- to 5-year-olds, 24-month-olds, and 18-month-olds. The older two groups were tested using the language-guided-looking method. The oldest group attended to vowels but not pitch. Surprisingly, 24-month-olds ignored not just pitch but sometimes vowels as well—conflicting with prior findings of phonological constraint at 24 months. The youngest group was tested using the Switch habituation method, half with additional phonetic variability in training. Eighteen-month-olds learned both pitch-contrasted and vowel-contrasted words, whether or not additional variability was present. Thus, native-language phonological constraint was not evidenced prior to 30 months (Quam & Swingley, 2010). We contextualize our findings within other recent work in this area.

Research in the U.S. and other Western countries shows that children’s early gesture use, which starts prior to verbal communication, is an important predictor of children’s later language development. Despite increasing efforts to study gesture use in diverse contexts, most of our knowledge on the role of gesture is largely based on populations of Western countries. In this study, we add to the growing body of international research by examining gesture use by 31 mothers and their 14-month-old infants (12 girls) in South Korea and investigate the gestures used during interaction, and whether early gesture use at 14 months predicts Korean children’s later language skills at 36 months. The results showed that in addition to using gestures observed in other cultural contexts, Korean mother-child dyads used culturally specific gesture (i.e., bowing), showing an early sign of socialization that starts with preverbal children. In addition, Korean infants’ index-finger pointing, but not showing and giving, predicted their later receptive and expressive vocabulary skills at 36 months, providing additional support for the importance of pointing in early language development.

Efficiently processing information from faces in infancy is foundational for nonverbal communication. We studied individual differences in 5-month-old infants' (N = 517) sustained attention to faces and preference for emotional faces. We assessed the contribution of genetic and environmental influences to individual differences in these gaze behaviors, and the association between these traits and other concurrent and later phenotypes. We found an association between the mean duration of looking at a face (before looking away from it) at 5 months and socio-communicative abilities at 14 months (β = 0.17, 95% CI: 0.08; 0.26, p < 0.001). Sustained attention to faces predicted socio-communicative abilities over and above variance captured by mean fixation duration. We also found a statistically significant but weak tendency to prefer looking at smiling faces (relative to neutral faces), but no indication that variability in this behavior was explained by genetic effects. Moderate heritability was found for sustained attention to faces (A = 0.23, CI: 0.06; 0.38), while shared environmental influences were non-significant for both phenotypes. These findings suggest that sustained looking at individual faces before looking away is a developmentally significant ‘social attention’ phenotype in infancy, characterized by moderate heritability and a specific relation to later socio-communicative abilities.

Elevated psychological distress, experienced by pregnant women and parents, has been well-documented during the COVID-19 pandemic. Most research focuses on the first 6-months postpartum, with single or limited repeated measures of perinatal distress. The present longitudinal study examined how perinatal distress, experienced over nearly 2 years of the COVID-19 pandemic, impacted toddler socioemotional development. A sample of 304 participants participated during pregnancy, 6-weeks, 6-months, and 15-months postpartum. Mothers reported their depressive, anxiety, and stress symptoms, at each timepoint. Mother-reported toddler socioemotional functioning (using the Brief Infant–Toddler Social and Emotional Assessment) was measured at 15-months. Results of structural equation mediation models indicated that (1) higher prenatal distress was associated with elevated postpartum distress, from 6-weeks to 15-months postpartum; (2) associations between prenatal distress and toddler socioemotional problems became nonsignificant after accounting for postpartum distress; and (3) higher prenatal distress was indirectly associated with greater socioemotional problems, and specifically elevated externalizing problems, through higher maternal distress at 6 weeks and 15 months postpartum. Findings suggest that the continued experience of distress during the postpartum period plays an important role in child socioemotional development during the COVID-19 pandemic.

For pregnant women, the COVID-19 pandemic has resulted in unprecedented stressors, including uncertainty regarding prenatal care and the long-term consequences of perinatal infection. However, few studies have examined the role of this adverse event on maternal wellbeing and infant socioemotional development following the initial wave of the pandemic when less stringent public health restrictions were in place. The current study addressed these gaps in the literature by first comparing prenatal internalizing symptoms and infant temperament collected after the first wave of the pandemic to equivalent measures in a pre-pandemic sample. Second, associations between prenatal pandemic-related stress and infant temperament were examined. Women who were pregnant during the COVID-19 pandemic endorsed higher pregnancy-specific anxiety relative to the pre-pandemic sample. They also reported greater infant negative emotionality and lower positive affectivity and regulatory capacity at 2 months postpartum. Prenatal infection stress directly predicted infant negative affect. Both prenatal infection and preparedness stress were indirectly related to infant negative emotionality through depression symptoms during pregnancy and at 2 months postpartum. These results have implications for prenatal mental health screening procedures during the pandemic and the development of early intervention programs for infants born to mothers during this adverse event.

Cross-task stability refers to performance consistency across different settings and measures of the same construct. Cross-task stability can help us understand developmental processes, including how risks such as preterm birth affect outcomes. We investigated cross-task stability of attention control in 32 preterm and 39 term infants. All infants had the same chronological age at time of testing (5 months) but varied in gestational age (GA) at birth (30–42 weeks). Infants completed an experimental attention following task with a researcher and a naturalistic play observation with their mothers. Both preterm and term infants demonstrated attention following in the experimental task. GA and flexibility of attention were related: the likelihood of no turn trials decreased with increasing GA. To evaluate cross-task stability, we compared attention performance in the experimental and naturalistic settings. Flexible attention shifts on the experimental task were positively related to attention to objects in the naturalistic observation. Furthermore, the association between flexible attention shifts on the experimental task and attention to objects in the naturalistic observation was moderated by GA. Our study provides initial evidence that the consolidation of attention control increases with GA. These findings highlight the value of comparing experimental and observational measures of attention.

The valid assessment of vocabulary development in dual-language-learning infants is critical to developmental science. We developed the Dual Language Learners English-Spanish (DLL-ES) Inventories to measure vocabularies of U.S. English-Spanish DLLs. The inventories provide translation equivalents for all Spanish and English items on Communicative Development Inventory (CDI) short forms; extended inventories based on CDI long forms; and Spanish language-variety options. Item-Response Theory analyses applied to Wordbank and Web-CDI data (n = 2603, 12–18 months; n = 6722, 16–36 months; half female; 1% Asian, 3% Black, 2% Hispanic, 30% White, 64% unknown) showed near-perfect associations between DLL-ES and CDI long-form scores. Interviews with 10 Hispanic mothers of 18- to 24-month-olds (2 White, 1 Black, 7 multi-racial; 6 female) provide a proof of concept for the value of the DLL-ES for assessing the vocabularies of DLLs.

Adults and infants as young as 4 months old orient to pointing gestures. Although adults are shown to orient faster to index-finger pointing than other hand shapes, it is unknown whether hand shapes influence infants' perception of pointing. In this study, we used a spatial cueing paradigm on an eye tracker to investigate whether and to what extent adults and 12-month-old infants orient their attention in the direction of pointing gestures with different hand shapes: index finger, whole hand, and pinky finger. Furthermore, we assessed infants' and their parents' pointing production. Results revealed that adults showed a reliable cueing effect: shorter saccadic reaction times (SRTs) to congruent than incongruent targets, for all hand shapes. However, they did not show a larger cueing effect triggered by the index or any other finger. This contradicts previous findings and is discussed with respect to the differences in methodology. Infants showed a cueing effect only for the whole hand but not for the index or pinky fingers. The current results suggest that infants' orienting to pointing may be more robust for the whole hand shape in the first year, and tuning in to the social-communicative relevance of the canonical index finger shape may develop later or require additional social-communicative cues.

Prior research suggests that across a wide range of cognitive, educational, and health-based measures, first-born children outperform their later-born peers. Expanding on this literature using naturalistic home-recorded data and parental vocabulary reports, we find that early language outcomes vary by number of siblings in a sample of 43 English-learning U.S. children from mid-to-high socioeconomic status homes. More specifically, we find that children in our sample with two or more—but not one—older siblings had smaller productive vocabularies at 18 months, and heard less input from caregivers across several measures than their peers with less than two siblings. We discuss implications regarding what infants experience and learn across a range of family sizes in infancy.

Experience with an object's photograph changes 9-month-olds’ preference for the referent object, confirming they can represent objects from pictures. However, picture-based representations appear weaker than object-based representations. The current study's first objective was to investigate age differences in object recognition memory after familiarization with objects' pictures. The second objective was to test whether age differences in object permanence sensitivity with picture-based representations match those found with object-based representations, whereby 7-month-olds search more for familiar hidden objects but 11-month-olds search more for novel ones. Six- and 11-month-olds were familiarized with an object's photo and tested on their representation of the real object by comparing their reaching for it versus a novel object. Objects were visible under conditions testing recognition memory and hidden under conditions testing object permanence. Like 9-month-olds, 6- and 11-month-olds preferred novelty with visible objects, showing early object recognition after picture familiarization, as well as developmental continuity. Unlike 9-month-olds, who switched to preferring familiarity with hidden objects, 6- and 11-month-olds switched to null preference. This pattern fails to match 7- and 11-month-olds’ hidden-object preferences after familiarization with real objects, revealing discontinuity in sensitivity to object permanence after picture familiarization, and suggesting that picture-based representations are weaker than object-based ones.