Infancy最新文献

There is robust evidence that infants' gestures and vocalisations and caregivers' contingent responses predict later child vocabulary. Recent studies suggest that dyadic combinations of infants' behaviors and caregivers' responses are more robust predictors of children's vocabularies than these behaviors separately. Previous studies have not yet systematically compared different types of dyadic combinations. This study aimed to compare the predictive value of (a) frequencies of infants' behaviors (vocalisations, points, and shows + gives) regardless of caregivers' responses, (b) frequencies of infants' behaviors that elicited verbal responses, (c) frequencies of infants' behaviors that elicited multimodal responses, and (d) frequencies of infants' behaviors that did not elicit any responses from caregivers. We examined 114 caregiver-infant dyads at 9-11 months and children's concurrent and longitudinal vocabulary outcomes at 2-4 years. We found that infants' points elicited a large proportion of verbal responses from caregivers which were related to children's later receptive vocabularies. We also found that only shows + gives that elicited caregivers' responses related to infants' concurrent gesture repertoires. In contrast, infants' behaviors that did not elicit responses negatively related to child vocabulary. The results highlight the importance of examining dyadic combinations of infants' behaviors and caregivers' responses during interactions when examining relations to children's vocabulary development.

Many in-lab studies have demonstrated that the distribution of word learning moments affects the strength and quality of word representations. How are words distributed in speech to children in their daily lives, and how is distribution related to other input characteristics? The present study analyzes transcripts of language input to English-learning infants from three longitudinal, naturalistic corpora captured between 6 and 39 months of age. To describe how word frequency varies across time, we calculated dispersion scores for all word types for each child. Dispersion quantifies the deviation of observed frequencies in each recording session from expected (uniform across sessions) word frequency, providing a measure of how evenly word utterances were spread across sessions. Dispersion is strongly correlated with frequency and moderately correlated with concreteness across all corpora, such that high frequency and low concreteness words are more evenly dispersed. Correlations with measures of age of acquisition (AoA) varied across corpora, and dispersion did not reliably predict AoA above and beyond frequency and concreteness. The contradiction between the current results and results from in-lab experiments is discussed. This study provides a foundation to explore how word learning unfolds across time and contexts in the real world.

Infants are sensitive to distortions to the global configurations of bodies by 3.5 months of age, suggesting an early onset of body knowledge. It is unclear, however, whether such sensitivity indicates knowledge of the location of specific body parts or solely reflects sensitivity to the overall gestalt of bodies. This study addressed this issue by examining whether, like adults, infants attend to specific locations where body parts have been reorganized. Results show that adults and 5-month-olds, but not 3.5-month-olds, allocated more attention to the body joint areas (e.g., where the arm connects to the shoulder) that were reorganized versus ones that were typical. To examine whether this kind of processing is driven by low-level features, 5-month-olds were tested on images in which the head was removed. Infants no longer exhibited differential scanning of typical versus reorganized bodies. Results suggest that 5-month-olds are sensitive to the location of body parts, thereby demonstrating adult-like response patterns consistent with early expertise in body processing. The contrasting failure of 3.5-month-olds to exhibit sensitivity to the reorganization suggests a developmental change between these ages.

Previous work has found that shy children show chance-level disambiguation and retention of novel word meanings in a typical lab-based word learning task. This effect could be explained in terms of shy children's aversion to unfamiliarity disrupting the requisite attentional processes, because the task is marked by a high degree of unfamiliarity. To test this argument, we examined whether increasing the familiarity of the task facilitates shy children's ability to form and retain word meanings. Two-year-old children (N = 23) took part in a word learning task in which their caregiver acted as the experimenter. On referent selection trials, children were presented with sets of three objects, one novel and two familiar, and were asked for either a familiar object using its known label, or a novel object using a novel word. Children were then tested on their retention of the previously formed novel word-object mappings. In this context of increased familiarity, shyness was unrelated to performance on referent selection trials. However, shyness was positively related to children's retention of the word-object mappings, meaning that shyer children outperformed less-shy children on this measure of word learning. These findings show that context-based familiarity interacts with intrinsic individual differences to affect word learning performance.

The current study examined the extent to which labels shape visuocortical processing during the first year of life during a brief (~6-min) associative learning task. Images of computer-generated artificial objects were paired with either individual-level (e.g., Jimmy, Boris) or category-level labels (e.g., Hitchel) while event-related potentials were recorded in response to the onset of the visual stimulus in 6- (n = 41), 9- (n = 27), and 12-month-old (n = 28) infants. Analyses examined experience-dependent visuocortical changes within and across trials, label conditions, and ages. Overall, results demonstrate that infants deploy greater visuocortical resources during the first half of associative learning trials and to stimuli paired with category-level relative to individual-level labels. Waveform morphologies also differed between stimuli paired with individual- and category-level labels and across the age groups, with more complex deflections and amplitude differences between label type at 9- and 12-month-olds, but not 6-month-old infants. The present results highlight the importance of associative learning during infancy and suggest that category- versus individual-level labels differentially direct infant attention and visuocortical processing.

This article reviews empirical methods and findings on early language discrimination, questioning rhythm-class based hypotheses on language discrimination in infancy, as well as the assumption that early language discrimination is driven primarily (or solely) by temporal prosodic cues. The present work argues that within-rhythm class discrimination which – according to the rhythmic hypothesis – is not applicable very early in life, has not been sufficiently tested with infants under 4 months of age, that familiarity with a language is not a prerequisite for its discrimination from another rhythmically similar language, and that the temporal rhythm properties may not universally be the primary cues to language discrimination. Although rhythm taxonomy is now by many understood as outdated, some developmental literature still draws on the assumption that rhythm classification determines infants' language discrimination; other studies consider rhythm along a continuous scale and only a few account for cues to language discrimination other than temporal ones. It is proposed that studies on early language discrimination systematically test the contribution of other than temporal rhythm cues, similarly to recent work on multidimensional psychoacoustic salience in the acquisition of segmental categories.

Developmental plasticity refers to conditions and circumstances that increase phenotypic variability. In infancy, plasticity expands and contracts depending on domains of functioning, developmental history, and timing. In terms of language processing, infants attend to and discriminate both native and non-native phonetic contrasts, but selectively attune to their native phonemes by the end of the first postnatal year. However, relevant studies have excluded factors regarded as promoters of attention such as infant-directed (ID) speech, synchronous multimodal presentations, and female speakers. Here we investigated whether English-learning 11-month-olds would discriminate a non-native phonetic contrast while manipulating these factors. Results showed significant discrimination of the non-native contrast, regardless of speech register, provided that they were presented by a dynamic female speaker. Interestingly, when a static object or a dynamic male ID speaker replaced the female, no significant discrimination was found. These results show infants to be capable of discriminating non-native phonetic contrasts in an enhanced context at an age when they have been characterized as not being able to do so. Synchronized, multimodal information from female speakers allowed infants to perceive difficult non-native phonemes, highlighting the importance of an ecologically valid context for studying speech perception and language learning in early development.

High-quality early care and education (ECE) programs are associated with positive outcomes, especially for children from low-income families. During the initial COVID-19 pandemic lockdown many of these families faced an abrupt halt to ECE. Here, we examined how toddlers from economically disadvantaged backgrounds enrolled in high-quality ECE programs in the United States during the 2020 pandemic (n = 48) fared on cognitive and socioemotional outcomes compared to a 2019 pre-pandemic cohort (n = 94) and a pandemic 2021 cohort (n = 132). Toddlers in the 2020 cohort scored significantly lower on executive function compared to toddlers in 2019 and 2021 cohorts. Toddlers in the 2020 cohort had higher ratings self-regulation compared to the pre-pandemic cohort, but not 2021 cohort. There were no differences on attachment ratings between cohorts. Findings suggest that the abrupt halt to ECE programs due to the COVID-19 pandemic impacted US toddlers’ cognitive and socioemotional abilities. This underscores the importance of continued high-quality ECE for infants and toddlers from low-income families during disruptive times. Further work is needed to investigate the long-term impacts of experiencing an abrupt halt to ECE due to COVID-19.

Young infants' face perception capabilities quickly tune to the features of their primary caregiver. The current study examines whether infants distinguish faces in a more conceptual manner using a manual-search, violation of expectation task that has previously been used to test kind-based individuation. We tested how well infants between 11 and 27 months of age individuated faces that varied by superordinate category (human vs. non-human in Experiment 1) subordinate category (individual identity in Experiment 2) or by race (White vs. Black, Experiments 1 & 2). We assessed individuation by quantifying the difference in infants' duration of reaching within an empty box between trials when the box was unexpectedly empty and expectedly empty. We found evidence of individuation across all ages and conditions, but with within-infant variation. On average, infants individuated face from non-face stimuli (Experiment 1), individual face identities (Experiment 2), and White versus Black faces (Experiments 1 & 2). These findings suggest that 1- to 2-year-old infants use distinct human face features to represent individuals across time and space. We discuss this evidence for race-based individuation and related complexities of face identity in terms of implications for conceptual development for faces in the first years of life.

This study investigates attention modulation as a function of infant directed (ID) versus adult directed (AD) speech in seven-month-old infants using electroencephalographic measures. In three experiments, infants were presented with either ID speech or AD speech as stimuli, followed by highly variable images of inanimate objects as targets. In Experiment 1 (N = 18), images were preceded by ID or AD speech with semantic content (“Look here”). Contrary to hypothesis, targets preceded by AD speech elicited increased amplitude of the Negative central (Nc) component compared to targets preceded by ID speech, indicating increased attention. Experiment 2 (N = 23) explored whether ID versus AD speech influences attention allocation also without semantic content. The same targets were either preceded by human voice sounds without semantic content (“Uh-Ah”) following the prosody of either ID or AD speech register. No differences in attention allocation or object processing were observed. Experiment 3 (N = 18) contrasted ID speech with and without semantic content and found enhanced attention allocation following stimuli without semantic content, but increased object processing following stimuli with semantic content. Overall, the effects observed here are consistent with the idea that less familiar speech stimuli increase attention for subsequent objects. Semantic content of stimuli increased the depth of object processing in 7-month-olds.