Birthweight moderates the association between chronological age and infants' abilities to respond to cues for joint attention.

Infants born preterm are more likely than ever to survive, but relatively little is known about the factors that influence their subsequent sociocognitive development. Responding to joint attention (RJA) is a pivotal skill that is likely supported by biological preparedness at birth and ex-utero social experience. The goals of this study are to evaluate the relative roles of chronological age, gestation duration, and birthweight for early RJA and examine birthweight as a potential moderator of the associations between chronological age and RJA. This study leveraged a mixed longitudinal design of infants (N = 256, obs = 421) from 8 to 16 months of chronological age. Results show that chronological age and gestation duration both explain unique variation in RJA. Further, birthweight exhibits quadratic relations with RJA. Birthweight moderates the association between chronological age and RJA; infants born heavier demonstrate faster RJA growth compared to those born smaller. Findings suggest that birth weight, an index of nutrient sufficiency in utero and biological preparedness, may constrain or afford early RJA development, consistent with the Developmental Origins of Health and Disease (DoHAD) hypothesis. Findings inform our understanding of the roles of biological preparedness and experience in shaping RJA and help disaggregate potential mechanisms of prematurity-related challenges to social cognitive development.

Measurement matters: An individual differences examination of family socioeconomic factors, latent dimensions of children's experiences, and resting state functional brain connectivity in the ABCD sample.

The variation in experiences between high and low-socioeconomic status contexts are posited to play a crucial role in shaping the developing brain and may explain differences in child outcomes. Yet, examinations of SES and brain development have largely been limited to distal proxies of these experiences (e.g., income comparisons). The current study sought to disentangle the effects of multiple socioeconomic indices and dimensions of more proximal experiences on resting-state functional connectivity (rsFC) in a sample of 7834 youth (aged 9-10 years) from the Adolescent Brain Cognitive Development (ABCD) study. We applied moderated nonlinear factor analysis (MNLFA) to establish measurement invariance among three latent environmental dimensions of experience (material/economic deprivation, caregiver social support, and psychosocial threat). Results revealed measurement biases as a function of child age, sex, racial group, family income, and parental education, which were statistically adjusted in the final MNLFA scores. Mixed-effects models demonstrated that socioeconomic indices and psychosocial threat differentially predicted variation in frontolimbic networks, and threat statistically moderated the association between income and connectivity between the dorsal and ventral attention networks. Findings illuminate the importance of reducing measurement biases to gain a more socioculturally-valid understanding of the complex and nuanced links between socioeconomic context, children's experiences, and neurodevelopment.

Capturing Environmental Dimensions of Adversity and Resources in the Context of Poverty Across Infancy Through Early Adolescence: A Moderated Nonlinear Factor Model.

Income, education, and cumulative-risk indices likely obscure meaningful heterogeneity in the mechanisms through which poverty impacts child outcomes. This study draws from contemporary theory to specify multiple dimensions of poverty-related adversity and resources, with the aim of better capturing these nuances. Using data from the Family Life Project (N = 1,292), we leveraged moderated nonlinear factor analysis (Bauer, 2017) to establish group- and longitudinally invariant environmental measures from infancy to early adolescence. Results indicated three latent factors-material deprivation, psychosocial threat, and sociocognitive resources-were distinct from each other and from family income. Each was largely invariant across site, racial group, and development and showed convergent and discriminant relations with age-twelve criterion measures. Implications for ensuring socioculturally valid measurements of poverty are discussed.

Longitudinal change in restricted and repetitive behaviors from 8-36 months.

BACKGROUND: Restricted and repetitive behaviors (RRBs) are core features of autism spectrum disorder (ASD) and one of the earliest behavioral signs of ASD. However, RRBs are also present in typically developing (TD) infants, toddlers, and preschool-aged children. Past work suggests that examining change in these behaviors over time is essential to distinguish between normative manifestations of these behaviors and behaviors that denote risk for a neurodevelopmental disorder. One challenge in examining changes in these behaviors over time is that most measures of RRBs have not established longitudinal measurement invariance. The aims of this study were to (1) establish measurement invariance in the Repetitive Behavior Scales for Early Childhood (RBS-EC), a parent-report questionnaire of RRBs, and (2) model developmental change in RRBs from 8 to 36 months. METHODS: We collected RBS-EC responses from parents of TD infants (n = 180) from 8 to 36 months (n = 606 responses, with participants contributing an average of 3-time points). We leverage a novel methodological approach to measurement invariance testing (Bauer, Psychological Models, 22(3), 507-526, 2017), moderated nonlinear factor analysis (MNLFA), to determine whether the RBS-EC was invariant across age and sex. We then generated adjusted factor score estimates for each subscale of the RBS-EC (repetitive motor, self-directed, and higher-order behaviors), and used linear mixed effects models to estimate between- and within-person changes in the RBS-EC over time. RESULTS: The RBS-EC showed some non-invariance as a function of age. We were able to adjust for this non-invariance in order to more accurately model changes in the RBS-EC over time. Repetitive motor and self-directed behaviors showed a linear decline from 8 to 36 months, while higher-order behaviors showed a quadratic trajectory such that they began to decline later in development at around 18 months. Using adjusted factor scores as opposed to unadjusted raw mean scores provided a number of benefits, including increased within-person variability and precision. CONCLUSIONS: The RBS-EC is sensitive enough to measure the presence of RRBs in a TD sample, as well as their decline with age. Using factor score estimates of each subscale adjusted for non-invariance allowed us to more precisely estimate change in these behaviors over time.

Infants' gaze exhibits a fractal structure that varies by age and stimulus salience.

The development of selective visual attention is critical for effectively engaging with an ever-changing world. Its optimal deployment depends upon interactions between neural, motor, and sensory systems across multiple timescales and neurocognitive loci. Previous work illustrates the spatio-temporal dynamics of these processes in adults, but less is known about this emergent phenomenon early in life. Using data (n = 190; 421 visits) collected between 3 and 35 months of age, we examined the spatio-temporal complexity of young children's gaze patterns as they viewed stimuli varying in semantic salience. Specifically, we used detrended fluctuation analysis (DFA) to quantify the extent to which infants' gaze patterns exhibited scale invariant patterns of nested variability, an organizational feature thought to reflect self-organized and optimally flexible system dynamics that are not overly rigid or random. Results indicated that gaze patterns of even the youngest infants exhibited fractal organization that increased with age. Further, fractal organization was greater when children (a) viewed social stimuli compared to stimuli with degraded social information and (b) when they spontaneously gazed at faces. These findings suggest that selective attention is well-organized in infancy, particularly toward social information, and indicate noteworthy growth in these processes across the first years of life.

Restricted, Repetitive, and Reciprocal Social Behavior in Toddlers Born Small for Gestation Duration.

OBJECTIVE: To characterize restricted and repetitive behaviors (RRBs) and reciprocal social behaviors (RSBs) in a large sample of toddlers who represent a range of birth weights and gestation durations. STUDY DESIGN: A battery of questionnaires characterizing demographic information and measuring RRBs and RSBs were completed by parents of toddlers between the ages of 17-26 months (n = 1589 total; n = 98 preterm). The association between birth weight and/or gestation duration and the primary outcome measures (RRBs and RSBs as ascertained through the Repetitive Behavior Scale for Early Childhood and the Video-Referenced Rating of Reciprocal Social Behavior) were tested by using hierarchical multivariate multiple regression. RESULTS: Toddlers born preterm and full term did not differ on RRBs or RSBs. However, there were significant associations between birth weight percentile for gestation duration (BPGD) and RRBs (ß = -2.1, P = .03), above and beyond the effects of age, sex, and vocabulary production. Similarly, there was a significant association between BPGD and RSBs (ß = -1.8, P = .02), above and beyond the effects of age, sex, and vocabulary production. CONCLUSIONS: These findings demonstrate that BPGD better predicted putative antecedents of adverse psychological outcomes-specifically, RRBs and RSBs-than gestation duration alone. These findings provide insight to the link between preterm birth and suboptimal behavioral/psychological outcomes and suggest that high birth weight, which may reflect a more optimal intrauterine environment, may serve as a protective factor irrespective of gestation duration.

A Longitudinal Investigation of Preferential Attention to Biological Motion in 2- to 24-Month-Old Infants.

Preferential attention to biological motion is an early-emerging mechanism of adaptive action that plays a critical role in social development. The present study provides a comprehensive longitudinal mapping of developmental change in preferential attention to biological motion in 116 infants at 7 longitudinal time points. Tested repeatedly from 2 until 24 months of age, results reveal that preferential attention to biological motion changes considerably during the first months of life. Previously reported preferences in both neonates and older infants are absent in the second month but do reemerge by month 3 and become increasingly pronounced during the subsequent two years. These results highlight the second month of life as a potentially critical transition period in social visual engagement.