Relationship between maternal grit and effortful control among 18-21-month-old toddlers.

Grit is known to be effective for long-term academic and social success. However, few studies have focused on the role of grit in parenting and its effect on the development of grit in children. Therefore, this study investigated the effect of maternal grit on children's effortful control (EC), which is thought to be a precursor to grit, using parenting as a mediating factor. Participants in the current study were 412 children (age range: 18-21 months, M = 34.67 months, SD = 4.51 months) and their mothers. We assessed maternal grit, parenting style, maternal EC, and child EC, and found that maternal grit, maternal EC, and parenting style were positively correlated with child EC. Furthermore, maternal grit was related to EC in children not only directly, but also indirectly through responsive parenting. Additionally, maternal grit was found to be directly related to child EC only when assessed separately from maternal EC. The current study's findings suggest that maternal grit is directly related to EC in children in a way that differs from the mother's EC in child-rearing situations.

Large-scale data decipher children's scale errors: A meta-analytic approach using the zero-inflated Poisson models.

Scale errors are intriguing phenomena in which a child tries to perform an object-specific action on a tiny object. Several viewpoints explaining the developmental mechanisms underlying scale errors exist; however, there is no unified account of how different factors interact and affect scale errors, and the statistical approaches used in the previous research do not adequately capture the structure of the data. By conducting a secondary analysis of aggregated datasets across nine different studies (n = 528) and using more appropriate statistical methods, this study provides a more accurate description of the development of scale errors. We implemented the zero-inflated Poisson (ZIP) regression that could directly handle the count data with a stack of zero observations and regarded developmental indices as continuous variables. The results suggested that the developmental trend of scale errors was well documented by an inverted U-shaped curve rather than a simple linear function, although nonlinearity captured different aspects of the scale errors between the laboratory and classroom data. We also found that repeated experiences with scale error tasks reduced the number of scale errors, whereas girls made more scale errors than boys. Furthermore, a model comparison approach revealed that predicate vocabulary size (e.g., adjectives or verbs), predicted developmental changes in scale errors better than noun vocabulary size, particularly in terms of the presence or absence of scale errors. The application of the ZIP model enables researchers to discern how different factors affect scale error production, thereby providing new insights into demystifying the mechanisms underlying these phenomena. A video abstract of this article can be viewed at https://youtu.be/1v1U6CjDZ1Q RESEARCH HIGHLIGHTS: We fit a large dataset by aggregating the existing scale error data to the zero-inflated Poisson (ZIP) model. Scale errors peaked along the different developmental indices, but the underlying statistical structure differed between the in-lab and classroom datasets. Repeated experiences with scale error tasks and the children's gender affected the number of scale errors produced per session. Predicate vocabulary size (e.g., adjectives or verbs) better predicts developmental changes in scale errors than noun vocabulary size.

Mask wearing in Japanese and French nursery schools: The perceived impact of masks on communication.

Due to the global COVID-19 pandemic, covering the mouth region with a face mask became pervasive in many regions of the world, potentially impacting how people communicate with and around children. To explore the characteristics of this masked communication, we asked nursery school educators, who have been at the forefront of daily masked interaction with children, about their perception of daily communicative interactions while wearing a mask in an online survey. We collected data from French and Japanese nursery school educators to gain an understanding of commonalities and differences in communicative behavior with face masks given documented cultural differences in pre-pandemic mask wearing habits, face scanning patterns, and communicative behavior. Participants (177 French and 138 Japanese educators) reported a perceived change in their own communicative behavior while wearing a mask, with decreases in language quantity and increases in language quality and non-verbal cues. Comparable changes in their team members' and children's communicative behaviors were also reported. Moreover, our results suggest that these changes in educators' communicative behaviors are linked to their attitudes toward mask wearing and their potential difficulty in communicating following its use. These findings shed light on the impact of pandemic-induced mask wearing on children's daily communicative environment.

Object labeling activates young children's scale errors at an early stage of verb vocabulary growth.

Scale errors are intriguing developmental phenomena in which young children attempt to perform impossible object-specific actions toward miniature-sized objects. Of several related cognitive abilities, lexical development during toddlerhood enhances scale error production by making objects' semantic representations dominant over perceptual information. To directly address the effect of activated semantic representations on scale errors, we examined whether and when object labeling affected scale errors. Toddlers aged 18 to 30 months (N = 72) performed a body-based scale error task twice: in one session with specific object labels provided (e.g., "chair") and in the other session with general pronouns provided (e.g., "this"). Using different developmental indices, including chronological age and productive vocabulary size of nouns, verbs, and adjectives, the enhancement effect of object labeling was detected only for children whose verb vocabulary size was classified into the medium group (3-26 words). Moreover, verb vocabulary size was determined to be the best predictor of scale error production among the candidate developmental indices. We also found that toddlers produced more scale errors in the first session that they performed the task compared with the second session. In addition to revealing that careful control of relevant factors (e.g., developmental indices, labeling, task repetition) is required for scale error research, this study sheds light on the relevance of verb vocabulary on scale errors.

Anticipatory regulation of cardiovascular system on the emergence of auditory-motor interaction in young infants.

Humans develop auditory-motor interaction to produce a variety of rhythmic sounds using body movements, which are often produced and amplified with tools, such as drumming. The extended production of sounds allows us to express a wide range of emotions, accompanied by physiological changes. According to previous studies, even young infants enhance movements in response to auditory feedback. However, their exhibition of physiological adaptation on the emergence of auditory-motor interaction is unclear. We investigated the movement and cardiac changes associated with auditory feedback to spontaneous limb movements in 3-month-old infants. The results showed that infants increased the frequency of limb movements inducing auditory feedback, while they exhibited a more regular rhythm of the limb movements. Furthermore, heart rate increase associated with the limb movement was first inhibited immediately after the timing of the auditory feedback, which may reflect sustained attention to the auditory stimuli. Then, through auditory-motor experience, the heart rate increase was inhibited even prior to the auditory feedback, leading to suppression of the peak intensity of the heart rate increase. These findings suggest that young infants regulate the cardiovascular system as well as limb movements in anticipation of the auditory feedback. The anticipatory regulation associated with movement and attentional changes may contribute to reduced cardiovascular stress in auditory-motor interaction, and provide a developmental basis for more sophisticated goal-directed behavior of producing rhythmic sounds.

Cognitive flexibility in 12-month-old preterm and term infants is associated with neurobehavioural development in 18-month-olds.

There is growing evidence that preterm children are at an increased risk of poor executive functioning, which underlies behavioural and attention problems. Previous studies have suggested that early cognitive flexibility is a possible predictor of later executive function; however, how it develops in infancy and relates to the later neurobehavioural outcomes is still unclear in the preterm population. Here, we conducted a longitudinal study to investigate oculomotor response shifting in 27 preterm and 25 term infants at 12 months and its relationship with general cognitive development and effortful control, which is a temperamental aspect closely associated with executive function, at 18 months. We found that moderate to late preterm and term infants significantly inhibited previously rewarded look responses, while very preterm infants did not show significant inhibition of perseverative looking at 12 months. Moreover, lower inhibition of perseverative looking was significantly associated with lower general cognitive development and attentional shifting at 18 months. These findings suggest that the early atypical patterns of oculomotor response shifting may be a behavioural marker for predicting a higher risk of negative neurobehavioural outcomes, including attention-related problems in preterm children.

Longitudinal assessment of social attention in preterm and term infants: Its relation to social communication and language outcome.

Preterm birth has been reported to be associated with an increased risk of social communication and language problems. Recently, we found that preterm infants showed atypical patterns of social attention compared with term infants. However, it is still unknown how social attention develops and whether the individual differences are associated with developmental outcomes for social communication and language in preterm infants. The social attention of preterm and term infants at 6, 12, and 18 months was investigated using two types of social attention tasks (human-geometric preference task and gaze-following task). The Modified Checklist for Autism in Toddlers (M-CHAT) and the MacArthur Communicative Development Inventory adapted for Japanese were measured at 18 months. We found that compared with term infants, preterm infants spent less time looking toward dynamic human images and followed another's gaze directions less frequently through 6, 12, and 18 months. Moreover, hierarchical multiple regression analysis revealed that less preference for dynamic human images and gaze-following abilities was associated with high M-CHAT and low language scores in preterm and term infants, respectively. These findings suggest that birth status affects development of social attention through 18 months and individual differences in social attention reflect differences in social communication and language outcomes.

Audiovisual speech perception and language acquisition in preterm infants: A longitudinal study.

BACKGROUND: Preterm infants have a higher risk of language delay throughout childhood. The ability to integrate audiovisual speech information is associated with language acquisition in term infants; however, the relation is still unclear in preterm infant. AIM AND METHODS: This study longitudinally investigated visual preference for audiovisual congruent and incongruent speech during a preferential looking task using eye-tracking in preterm and term infants at 6, 12, and 18 months of corrected age. The infants' receptive and expressive vocabulary at 12 and 18 months were obtained by parent report, using the Japanese MacArthur Communicative Development Inventory. RESULTS: We found that preterm infants did not clearly show visual preference for the congruent audiovisual display at any age, whereas term infants looked at the congruent audiovisual display longer than the incongruent audiovisual display at 6 and 18 months. Preterm infants' receptive and expressive vocabulary scores were lower than those of term infants at 12 and 18 months. Furthermore, the proportion of looking time toward the congruent audiovisual display at 6 months was positively correlated with receptive vocabulary scores at 12 and 18 months for both groups. CONCLUSIONS: These findings suggest that better audiovisual speech perception abilities are one factor that results in better language acquisition in preterm as well as term infants. Early identification of behaviors associated with later language in preterm infants may contribute to planning intervention for developmental problems.

Preference for Dynamic Human Images and Gaze-Following Abilities in Preterm Infants at 6 and 12 Months of Age: An Eye-Tracking Study.

Preterm children are reported to be at higher risk of social communication problems such as autism spectrum disorder compared with full-term infants. Although previous studies have suggested that preference for social stimuli in infancy is a possible indicator of later social communication development, little is known about this relation in preterm infants. We examined the gaze behavior of low-risk preterm and full-term infants at 6 and 12 months' corrected ages using two types of eye-tracking tasks, which measured 1) preference for social stimuli by biological motion and human geometric preference and 2) ability to follow another's gaze direction. We found that preterm (compared with full-term) infants at both 6 and 12 months of age spent less time looking toward dynamic human images, followed another's gaze less frequently, and looked for a shorter time at an object cued by another. Moreover, we found a positive correlation between looking time toward dynamic human images and frequency of gaze following at 12 months of age in full-term, but not preterm, infants. We discuss the relation between the atypical patterns of gaze behavior in preterm infants and their higher risk of later social communication problems.

Fundamental Frequency Variation of Neonatal Spontaneous Crying Predicts Language Acquisition in Preterm and Term Infants.

Spontaneous cries of infants exhibit rich melodic features (i.e., time variation of fundamental frequency [F0 ]) even during the neonatal period, and the development of these characteristics might provide an essential base for later expressive prosody in language. However, little is known about the melodic features of spontaneous cries in preterm infants, who have a higher risk of later language-related problems. Thus, the present study investigated how preterm birth influenced melodic features of spontaneous crying at term-equivalent age as well as how these melodic features related to language outcomes at 18 months of corrected age in preterm and term infants. At term, moderate-to-late preterm (MLP) infants showed spontaneous cries with significantly higher F0 variation and melody complexity than term infants, while there were no significant differences between very preterm (VP) and term infants. Furthermore, larger F0 variation within cry series at term was significantly related to better language and cognitive outcomes, particularly expressive language skills, at 18 months. On the other hand, no other melodic features at term predicted any developmental outcomes at 18 months. The present results suggest that the additional postnatal vocal experience of MLP preterm infants increased F0 variation and the complexity of spontaneous cries at term. Additionally, the increases in F0 variation may partly reflect the development of voluntary vocal control, which, in turn, contributes to expressive language in infancy.

Associations between respiratory arrhythmia and fundamental frequency of spontaneous crying in preterm and term infants at term-equivalent age.

This study investigated whether lower vagal function in preterm infants is associated with increased fundamental frequency (F0 ; frequency of vocal fold vibration) of their spontaneous cries. We assessed respiratory sinus arrhythmia (RSA) during quiet sleep as a measure of vagal function, and its relationship with the F0 of spontaneous cries in healthy preterm and term infants at term-equivalent age. The results showed that preterm infants have significantly lower RSA, and higher overall F0 than term infants. Moreover, lower RSA was associated with higher overall F0 in preterm infants, whereas higher RSA was positively associated with mean and maximum F0 , and a larger F0 range in term infants. These results suggest that individual differences in vagal function may be associated with the F0 of spontaneous cries via modulation of vocal fold tension in infants at an early developmental stage. © 2016 The Authors. Developmental Psychobiology Published by Wiley Periodicals, Inc. Dev Psychobiol 58:724-733, 2016.

Preterm birth is associated with an increased fundamental frequency of spontaneous crying in human infants at term-equivalent age.

Human infant crying has been researched as a non-invasive tool for assessing neurophysiological states at an early developmental stage. Little is known about the acoustic features of spontaneous cries in preterm infants, although their pain-induced cries are at a higher fundamental frequency (F0) before term-equivalent age. In this study, we investigated the effects of gestational age, body size at recording and intrauterine growth retardation (IUGR) on the F0 of spontaneous cries in healthy preterm and full-term infants at term-equivalent age. We found that shorter gestational age was significantly associated with higher F0, although neither smaller body size at recording nor IUGR was related to increased F0 in preterm infants. These findings suggest that the increased F0 of spontaneous cries is not caused by their smaller body size, but instead might be caused by more complicated neurophysiological states owing to their different intrauterine and extrauterine experiences.