Infancy最新文献

There is little systematically collected quantitative empirical data on how much linguistic input children in small-scale societies encounter, with some estimates suggesting low levels of directed speech. We report on an ecologically-valid analysis of speech experienced over the course of a day by young children (N = 24, 6–58 months old, 33% female) in a forager-horticulturalist population of lowland Bolivia. A permissive definition of input (i.e., including overlapping, background, and non-linguistic vocalizations) leads to massive changes in terms of input quantity, including a quadrupling of the estimate for overall input compared to a restrictive definition (only near and clear speech), while who talked to and around a focal child is relatively stable across input definitions. We discuss implications of these results for theoretical and empirical research into language acquisition.

The origin of face or language influences infants' perceptual processing and social learning behavior. However, it remains unclear how infants' social learning behavior is affected when both information are provided simultaneously. Hence, the current study investigated whether and how infants' social learning in terms of gaze following is influenced by face race and language origin of an interaction partner in an uncertain situation. Our sample consisted of 91 Caucasian infants from German speaking families. They were divided into 2 age groups: Younger infants were 5- to 8-month-old (n = 46) and the older infants 11- to 20-month-old (n = 45). We used a modified online version of the gaze following paradigm by Xiao and colleagues by varying face race (Caucasian, and Asian faces) and language (German and French) of a female actor. We recorded infants looking behavior via webcam and coded it offline. Our results revealed that older but not younger infants were biased to follow the gaze of own-race adults speaking their native language. Our findings show that older infants are clearly influenced by adults' ethnicity and language in social learning situations of uncertainty.

Research on infant and toddler reaching has shown evidence for motor planning after the initiation of the reaching action. However, the reach action sequence does not begin after the initiation of a reach but rather includes the initial visual fixations onto the target object occurring before the reach. We developed a paradigm that synchronizes head-mounted eye-tracking and motion capture to determine whether the latency between the first visual fixation on a target object and the first reaching movement toward the object predicts subsequent reaching behavior in toddlers. In a corpus of over one hundred reach sequences produced by 17 toddlers, we found that longer fixation-reach latencies during the pre-reach phase predicted slower reaches. If the slowness of an executed reach indicates reach difficulty, then the duration of pre-reach planning would be correlated with reach difficulty. However, no relation was found with pre-reach planning duration when reach difficulty was measured by usual factors and independent of reach duration. The findings raise important questions about the measurement of reach difficulty, models of motor control, and possible developmental changes in the relations between pre-planning and continuously unfolding motor plans throughout an action sequence.

Since birth, infants discriminate the biological motion (BM) revealed by point-light displays (PLDs). To date, no studies have explored whether newborns differentiate BM that approaches rather than withdraws from them. Yet, approach and withdrawal are two fundamental motivations in the socio-emotional world, key to developing empathy and prosocial behavior. Through a looking-behavior paradigm, we demonstrated that a few hours after birth, a human figure approaching attracted more visual attention than a human figure receding, showing that newborns are attuned to PLDs of others moving toward rather than walking away from them. Further, a withdrawing body appears to be less attractive than withdrawing scrambled points. Altogether, these observations support the existence of an early predisposition toward social closeness that might have its roots in an evolutionary perspective.

Measuring eye movements remotely via the participant's webcam promises to be an attractive methodological addition to in-person eye-tracking in the lab. However, there is a lack of systematic research comparing remote web-based eye-tracking with in-lab eye-tracking in young children. We report a multi-lab study that compared these two measures in an anticipatory looking task with toddlers using WebGazer.js and jsPsych. Results of our remotely tested sample of 18-27-month-old toddlers (N = 125) revealed that web-based eye-tracking successfully captured goal-based action predictions, although the proportion of the goal-directed anticipatory looking was lower compared to the in-lab sample (N = 70). As expected, attrition rate was substantially higher in the web-based (42%) than the in-lab sample (10%). Excluding trials based on visual inspection of the match of time-locked gaze coordinates and the participant's webcam video overlayed on the stimuli was an important preprocessing step to reduce noise in the data. We discuss the use of this remote web-based method in comparison with other current methodological innovations. Our study demonstrates that remote web-based eye-tracking can be a useful tool for testing toddlers, facilitating recruitment of larger and more diverse samples; a caveat to consider is the larger drop-out rate.

Effortful control (EC), a self-regulation skill, is associated with long-term developmental outcomes. Music has been associated with infant self-regulation and may be an intervention strategy for enhancing EC during toddlerhood. This investigation included 32 parent-child dyads from a previously conducted randomized controlled trial (RCT). Participants (9-15-months old at baseline) attended either a music enrichment program or a playdate control once a week for 1 year and monthly for an additional year. At age 3, participants completed snack and gift delay effortful control tasks. Groups were compared using one-way ANOVA. We found that participants in the music group had a significantly higher score during snack delay (music mean = 3.47 ± 0.94; control mean = 2.45 ± 1.51; p = 0.03; Cohen's d = 0.84). We did not find a significant group difference for latency to peek (music mean = 39.10 ± 20.10; control mean = 30.90 ± 19.88; p = 0.25; d = 0.57) or latency to touch (music mean = 105.73 ± 417.69; control mean = 98.35 ± 28.84; p = 0.38; d = 0.29) for the gift task. This study provides initial evidence that early participation in a music enrichment program may benefit later development of EC. This study is registered at ClinicalTrials.gov (NCT02936284).

We compared vocabulary sizes in comprehension and production between bilingual toddlers growing up in the United Kingdom (UK) and age-matched UK English monolinguals (12–36 months old) using parent-report vocabulary questionnaires. We found that bilingual toddlers' vocabulary sizes in English were smaller than the vocabulary sizes of their monolingual peers. Notably, this vocabulary gap was not found when groups were compared on conceptual vocabulary in comprehension. Conceptual scoring also reduced the vocabulary gap in production but group differences were still significant. Bilingual toddlers knew more words than monolinguals when words across their two languages were added together, for both comprehension and production. This large total vocabulary size could be attributed to a high proportion of doublets (cross-linguistic word pairs with the same meaning) in bilinguals' vocabularies. These findings are discussed in relation to language exposure, facilitation from cross-linguistic overlap and maturation constraints on vocabulary size.

Coparenting can be a development-enhancing or risk-promoting environment for infant regulatory capacity, mainly in the presence of adversity. This study aimed to analyze the association between positive and negative coparenting previous to the COVID-19 pandemic and infant regulatory capacity in the presence of the COVID-19 pandemic, an adverse condition. A sample of 71 first-born infants and their mothers and fathers from a longitudinal cohort in Portugal were assessed at 2 weeks postpartum before the COVID-19 pandemic and again at 6 months postpartum, before (n = 35) or during the COVID-19 pandemic (n = 36). Parents completed measures of positive and negative coparenting and infant regulatory capacity in both assessment waves. Results revealed that the presence of the COVID-19 pandemic moderates the association between mothers' and fathers' positive coparenting previous to the COVID-19 pandemic and infant regulatory capacity at 6 months. The association between positive coparenting and regulatory capacity was stronger in infants facing the COVID-19 pandemic, than in infants who did not face the COVID-19 pandemic. Positive coparenting previous to the COVID-19 pandemic may be a development-enhancing environment for infant regulatory capacity in the presence of the COVID-19 pandemic. Positive coparenting may buffer regulatory problems in infants facing adverse conditions.

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.

Although the arms participate in many forms of human locomotion, we know very little about when arm movements emerge during locomotor development. Here we investigated whether newborns would make tactile arm stepping movements when we supported them almost horizontally so their hands touched a surface and blocked their leg movements. Building off prior work showing that newborns make more crawling and air stepping leg movements when exposed to optic flows specifying forward and backward self-translation, we also examined whether newborns would make more tactile arm steps when exposed to forward and backward optic flows compared to a random optic flow that did not specify translation. We found that newborns can perform arm stepping and produce a significantly higher number of tactile arm steps in the optic flow condition specifying backward translation than in the random optic flow condition. Both translating optic flow conditions had significantly higher numbers of alternating arm steps than the random optic flow condition. These findings show that tactile arm stepping exists at birth and that optic flows can facilitate their production, similar to leg stepping. We argue that these results further support the idea that a quadrupedal organization underlies early upright stepping.