In upper elementary period school adjustment and the effect of parenting face a new set of dynamics. We assumed that parental supervision, affection, incoherence, over-expectation, over-interruption and logical explanation would have an effect on individual trajectories in the development of school adjustment. Additionally, we hypothesized that this model would be different among boys and girls. In this study we analyzed three waves of data collected from 2,378 children nationwide in South Korea. This data was gathered from the Panel Study of Korean Youth and Adolescents conducted by the National Youth Policy Institute(NYPI). Growth-curve longitudinal analysis was conducted and the results indicate that levels of school adjustment had decreased through the 4 th to 6 th grade. Parents' supervision, affection and logical explanation significantly predict children's initial school adjustment as well as their rate of decrease in their levels of school adjustment. Parents'

Sex differences in attachment are absent during infancy and early childhood, emerge in middle childhood with self-reports and doll-play tasks, and persist into adulthood, when they are most reliably detected in romantic attachment styles. In our previous work, we hypothesized that sex differences in attachment develop under the influence of adrenal androgens during the transition form early to middle childhood, following activation of hormone-sensitive neural pathways organized by prenatal and early postnatal exposure to sex hormones. In this study we tested the association between the right-hand 2D:4D digit ratio (a marker of early exposure to androgens and estrogen) and sexually differentiated dimensions of attachment in middle childhood assessed with the Coping Strategies Questionnaire (CSQ). In a sample of 285 Italian children aged 8-10 years, females scored lower in avoidance and higher in preoccupation, while no significant sex differences were observed in felt security. Consistent with our predictions, higher (feminized) digit ratios were significantly associated with lower avoidance and higher preoccupation scores in both males and females. In contrast, there was no significant association between digit ratio and felt security in either sex. These results corroborate the hypothesis that sex differences in attachment reflect the activation of sexually differentiated pathways organized in early development, and for the first time implicate sex hormones in the development of individual differences in attachment styles.

The purpose of this study was to examine longitudinal effects of father involvement in child-reaering during early childhood on first graders' school adjustment, focusing on the mediating role of executive function difficulties. By doing so, the present study attempted to investigate the importance of fathers' involvement in childcare during early childhood. Methods: This study used the 4th, 5th, and 8th data sets from the Panel Study on Korean Children. A total of 1,711 data were analyzed. Descriptive statistics analysis, Pearson correlation analysis, structural equation modeling analysis, and bootstrapping were conducted. Results: Fathers' rearing involvement during early childhood was found to have a positive effect on first graders' school adjustment by reducing levels in the children's executive function difficulties, with socioeconomic status and children's gender being considered as a confounder. However, fathers' rearing involvement during early childhood did not have a direct effect on first graders' school adjustment. Conclusion:The present study suggests that fathers' rearing involvement in early childhood is important for first graders' cognitive development and school adjustment in the long term. This study is meaningful in that it did not simply reveal the longitudinal influences of fathers' rearing involvement on children's elementary school adjustment, but also explained these influences through the development of children's executive skills.

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Objective: The purpose of this study was to investigate the relationship between breastfeeding duration and preschooler problem behavior, focusing on the mediating role of cognitive development. Methods: The data came from the Panel Study on Korean Children. The study sample included 926 participants. The statistical methods for the data analyses included descriptive statistics analysis, Pearson correlation analysis, partial correlation analysis, regression analysis, and the Sobel test. Results: Breastfeeding duration predicted preschooler cognitive development, internalizing problems, and externalizing problems after adjusting for potential confounding factors (i.e., sex, SES, temperament, and parenting style). Further, cognitive development fully mediated the relationship between breastfeeding duration and externalizing problems at age 5 years. Conclusion: The results from the current study support the hypothesis that breastfeeding predicts preschooler cognitive development and problem behavior after adjusting for confounding factors. Further, the relationship between breastfeeding duration and externalizing problems was explained via cognitive development. Based on these results, we recommend the practice of breastfeeding for healthy early childhood development.