<p dir="ltr">Loneliness is a perceived discrepancy between desired and experienced social relationships, which may arise from perceived lack of intimate attachment to another person (e.g., friend) or lack of involvement in larger networks (e.g., peer groups). The current study examined and compared how different aspects of friendship and peer group involvement predicted loneliness of Indonesian adolescents. Participants were 754 twelfth-grade Indonesian students (413 girls, mean age = 16.5 years). Loneliness was self-reported. Reciprocated friendships were calculated from within-grade nominations and friendship quality was obtained from ratings pertaining to each nominated friend. Peer groups were generated from Social Cognitive Mapping (SCM) and status indices were calculated from SCM and peer nominations. A concurrent SEM model was tested where quantity and self- and friend-perceived quality of friendship, group membership (i.e., within-group centrality), and status of the group in the larger network (i.e., group centrality status and group popularity status) predicted loneliness. All predictors had unique negative effects on loneliness with generally similar effect sizes except for friend-perceived friendship quality. An interaction between within-group centrality and group popularity status was found for boys. The results revealed that quantity and quality of friendship as well as position in the peer group and the status of the peer group were associated with loneliness. Being central in a group may be more important for those in low-status groups than high-status groups. Group-related indices were comparable to friendship indices as predictors of loneliness, which may be shaped by Indonesian culture where group involvement is valued more than intimate friendships.</p>

<p>Similarity in academic achievement among friends (i.e., academic homophily) can arise from two processes, selection and influence. This study applied stochastic actor-based modeling using SIENA to disentangle friendship selection and social influence regarding academic achievement of Chinese adolescents in a three-year longitudinal sample of 880 middle school students (400 girls, year 1 mean age = 13.33) and 525 high school students (284 girls, year 1 mean age = 16.45). SIENA analyses revealed significant selection and influence effects pertaining to academic achievement for both middle school students and high school students across three years. Chinese adolescents preferred friendships with similarly achieving or higher achieving peers but avoided friendships with lower achieving peers. Friends’ influence on academic achievement can be both beneficial and detrimental. Chinese adolescents were more likely to increase in achievement when they befriended high-achieving peers, but decreased achievement when they were friends with low-achieving peers. There were no significant sex differences or school year differences (i.e., the first to second years versus the second to third years) in selection or influence effects for academic achievement. Influence effects were stronger for middle school students than for high school students, but no significant grade level differences emerged for selection effects. This study expands upon prior research by simultaneously assessing selection and influence effects on academic achievement and further examining the direction and strength of selection and influence processes regarding academic achievement using sophisticated modeling analyses. These results provide insights into the important role of cultural context in peer relationships and academic development by considering the strong pressure Chinese adolescents experience to be academically successful.</p>

<p>This thesis tested and extended the peer socialization hypothesis, a psychosocial model that identifies the interpersonal and contextual conditions in which pubertal development is linked to delinquent behavior such as alcohol use. Although there is support for the hypothesis in early empirical work, particularly for female adolescents, more recent work has shown mixed results. Furthermore, there are gaps within the peer socialization hypothesis: a) the theory does not discuss if the mediation process pertains to male adolescents, b) it does not address the role of pubertal tempo, and c) it implies, but does not explicitly model, a role for tempo with regards to including other-sex friendships into the friend group. Using the Internet Surveys About You (iSAY) study (<em>n</em>=1020), the peer socialization hypothesis and proposed extensions were tested separately by sex. Female adolescents initiated inclusion of other-sex friends into the friend group earlier than male adolescents. However, there were no observed sex differences in the tempo of other-sex friendships. Female adolescents’ pubertal development was not related to their other-sex friendship development nor was pubertal development and other-sex friendship development related to their alcohol use. Male adolescents’ pubertal timing was associated with the timing of other-sex friendship uptake in that later maturing adolescents displayed earlier initiation of other-sex friendships. Male adolescents’ other-sex friendship development was not related to their alcohol use. Implications of this work are that other-sex friendships may no longer be a context of increased risk for alcohol use for early maturing adolescents and interventions targeting this social context may not be as effective. </p>

<p> Over two-thirds of youth participate in a structured sport, making it a vital context in which transactional relations with cognitive development can occur. Yet, little is known about how these constructs inform one another across childhood. Most previous studies have focused on health benefits of sport participation, or on demographic and family characteristics as predictors of participation. Though some previous literature has explored the cognitive impacts of sport participation during childhood, as well as whether early cognitive skills may predict later sport participation, critical gaps remain. Specifically, there is a need to investigate the extent to which there are longitudinal relations between these constructs as well as the nature of those associations throughout childhood. Thus, this dissertation examines whether: (1) participating in sports during preschool predicts kindergarten cognitive outcomes (i.e., executive functioning, math, language, literacy), (2) executive functioning and pre-academic skills (i.e., math, language, literacy) at 54 months predict participating in a structured sport (open-skilled, closed-skilled) in third and fifth grade, and (3) if there are bidirectional relations between executive functioning and academic outcomes (i.e., math, language, literacy) and structured sports (open-skilled, closed-skilled) in third and fifth grade. Findings from this dissertation indicated that associations between sport participation and cognition in children are complex, such that the direction of these associations likely depend on developmental period and conceptualization of sport. In particular, there may be positive transactional relations between early sport and cognitive skills, but not in middle childhood. Further, the results suggest that there may be bidirectional relations between open-skilled sport participation and executive functioning across childhood. In addition, almost all associations between closed-skilled sport participation and cognitive skills were nonsignificant. Thus, open-skilled sport participation may demand more cognitive resources than closed-skilled sport participation. Results from this dissertation reinforce the need to use intensive longitudinal data analysis to continue exploring transactional relations between sport participation, executive functioning, and academic skills. Finally, it is vital to reconsider how we evaluate sport participation in children and to include context-specific measures of participation that likely influence relations between these constructs. </p>

<p>Adolescents are highly sensitive to peer influence and thus at higher risk of acquiring problematic behaviors through peer interactions. However, adolescents vary in the extent to which they are influenced by their peers. Resistance to peer influence (RPI), the tendency to refuse undesired peer norms and peer pressure, is one of the crucial explanations for this variation. Prior to designing effective interventive plans to improve RPI, it is important to elucidate the pathways of how RPI develops in childhood and adolescence. Therefore, the present study leverages an adopted-at-birth design and proposes a moderated mediation model to examine whether: 1) child phenotypic impulsivity mediates the association between birth parent impulsivity and adolescent RPI; 2) child phenotypic self-esteem mediates the association between birth parent self-esteem and adolescent RPI; 3) adoptive parent responsiveness buffers the impulsivity pathway; and 4) adoptive parent responsiveness strengthens the self-esteem pathway. The sample consists of 538 family triads, with adopted child, birth parents, and adoptive parents, drawn from a sample of 561 families recruited from 45 adoption agencies in the United States. Birth parents’ impulsivity and self-esteem were measured to index heritable factors for phenotypic impulsivity and self-esteem. Adoptive parents’ responsiveness was measured via home observations. Impulsivity and self-esteem of adopted adolescent were reported by their adoptive parents, whereas RPI was assessed via self-report. Covariates included adolescent sex, age, and the openness to adoption between birth parents and adoptive parents. Results of structural equation models revealed that none of the proposed mediating or moderating pathways reached statistically significant levels. Overall, girls reported higher RPI than boys. For future studies, researchers may want to consider more accurate proxies of genetic factors for impulsivity and self-esteem, and repeated measures designs.</p>

<p>  </p> <p>Sleep is a critical component of early development, with over 8,000 hours spent asleep between a child's first and third birthday alone. Beginning in infancy, sleep is linked to several aspects of development, such as language, attention, and social communication. Thus, given its frequency and importance for infants and toddlers, sleep is among the most common topics raised by parents of typically and atypically developing children at well-child visits and beyond. The current dissertation includes three distinct, but integrated studies on sleep in early development. Specifically, study 1 addresses sleep in typically developing toddlers using videosomnography (an objective measure of sleep), study 2 addresses relations between sleep and attention in toddlers at low and high familial risk for ASD, and study 3 addresses prospective patterns of early sleep and development in children who later develop ASD. Overall, results from this dissertation highlight that sleep problems (e.g., night waking) can be expected even within well documented typical development. Findings from this dissertation have implications for sleep measurement in early childhood and suggest that using objective measures of sleep and developmental competence are critical for understanding normative sleep in typical and atypical development. </p>

<p dir="ltr">Military families are a unique context as they experience separation from the service member who is away from the family for a considerable duration of time for a job that puts them at risk of serious injury or death. Service members returning from deployments may display a variety of mental health difficulties including post-traumatic stress disorder, especially when they have combat experiences. Applying a family systems framework, this thesis examined the associations between both service members’ and significant others’ PTSD symptoms, their ineffective arguing, and their reports of their children’s externalizing behaviors across three time points during reintegration, or the stage in the deployment cycle when the service member returns to the family. The study tested hypotheses that these would decline over time, and that initial levels and the rate of change in ineffective arguing would mediate the effect of parental PTSD at Time 1 on children’s externalizing behaviors at Time 3. Using data from service members and significant others in 71 families (142 individuals), I estimated multilevel models using both mixed and the structural equation frameworks. I found that parental PTSD and ineffective arguing were stable across reintegration, with considerable inter-individual variation in these at baseline. There was a decrease in children’s externalizing behaviors across time. There were also significant differences in parents’ rating of children’s externalizing behaviors. I did not find evidence for mediation but did find an association between parental PTSD and baseline levels of ineffective arguing. Results suggest that while parental stress is linked with the couple’s functioning, there may be protective factors within families that act as sources of resilience for the children.</p><p><br></p>

<p dir="ltr">Abstract: Atypical frontal alpha asymmetry is the difference in EEG-measured alpha-band power between right and left hemispheres, and patterns of lateralization are thought to reflect motivational direction (approach/withdrawal) and affective processing. Increased rightward frontal alpha asymmetry is associated with tendency toward approach-related behavior often displayed in attention-deficit/hyperactivity disorder (ADHD), though findings have been inconsistent. While differences in results may be partially accounted for by within-diagnosis heterogeneity, growing evidence suggests individual response tendency and emotional salience of a situation may influence one another. Investigating the potential interactions between trait and state measured variables may therefore clarify lateralization patterns in ADHD. The current study measured frontal alpha asymmetry in a well-characterized sample of school-aged children with and without ADHD. EEG during standard resting-state and emotional passive-viewing tasks were recorded from 220 children (nADHD = 97). A semi-structured clinical interview and standardized rating scales were collected to assign DSM-5 diagnoses and temperament group belonging. Parent measures included the behaviorally-rated Temperament in Middle Childhood Questionnaire (TMCQ). Latent profile analysis within the ADHD group revealed two temperament subgroups: emotionally regulated and emotionally dysregulated (high anger and sadness). EEG assessment suggests children broadly produced a more rightward asymmetry while in resting state compared to a task-based condition, though show no notable differences between neutral and negative emotional task conditions. ADHD diagnostic status, temperament group, and sex assigned at birth did not impact patterns of asymmetry. Results emphasize measurement differences in frontal alpha asymmetry between lab-based tasks and further highlight the importance of state influences on alpha lateralization.</p>

<p dir="ltr">The present study explored the association between maternal use of food to soothe and maternal sensitivity, while considering the potential moderating role of child negative affectivity. Before addressing the key questions, the congruence and stability of key constructs at two different time points, 12 and 18 months, using both self-reported and observer-reported data, were examined. A nonclinical sample of 136 mother-child dyads were recruited. Maternal use of food to soothe, child negative affectivity, and maternal sensitivity were observed across lab visits at both time points, 12 and 18 months. Mothers completed questionnaires about maternal use of food to soothe and child negative affectivity at both time points. Structural Equation Modeling (SEM) was employed to analyze the associations and potential interaction effects between maternal sensitivity and child negative affectivity on maternal use of food to soothe.</p><p dir="ltr">Findings showed that maternal sensitivity was negatively associated with mothers’ use of food to soothe at 12 months in the lab, although this association was not observed at 18 months. Child negative affectivity did not moderate the significant association mentioned. The study also found low to moderate stability in mother-reported use of food to soothe, child negative affectivity, and maternal sensitivity across the two time points. Furthermore, the congruence between self-reported and observer-reported data on these practices was generally low, underscoring the challenges in measuring these behaviors.</p><p dir="ltr">The findings suggest that higher maternal sensitivity could potentially lower the frequency of using food as a soothing method at 12 months. Future research should aim to confirm these findings in more diverse populations and through less structured observational settings.</p>

<p dir="ltr">A major challenge to promoting effective early science and engineering education is the lack of reliable and validated assessments that align with current educational guidelines for science and engineering. Existing early science and engineering assessments either cover a narrow range of concepts and practices and/or are not designed in a way to evaluate and provide information within theorized dimensions of science and engineering knowledge and skills. The goals of this study were to develop a preschool science and engineering assessment and to examine the factor structure of children’s science and engineering knowledge and skills using the newly developed assessment. A 120-item assessment was developed and administered to 186 children (50.28% female) ages 3-to-5 years (<i>M </i>= 4.62 years, <i>SD</i> = 0.61 years). The overall best fitting structure of the assessment was found to be a three-dimensional model: disciplinary core ideas, science and engineering practices, and crosscutting concepts. Items that had low correlations with the overall test, loaded poorly onto their respective factors, or were found to provide overlapping information with other items (i.e., exhibited similar difficulties for the same content areas) were removed, resulting in a final and brief (48-item) version of the assessment. This study has important implications in that the newly developed science and engineering assessment can be used in both the research (e.g., evaluate curricula, interventions) and classroom (e.g., assess learning) settings to provide information at the dimension-level, and has the potential to transform how we view and instruct science and engineering during the early childhood years.</p>