Erken dönem yaşam stresinin ve mizacın bebeklerin kortizol düzeyleri ve bilişsel gelişimleri üzerindeki etkisi

Although early adversity, including being reared in institutional care or a low socioeconomic environment, influences children's development negatively, not all children are affected at the same level. This thesis aims to examine the role of early adversity and temperament in infants' cognitive development and their stress regulation systems. Study I longitudinally examined the cognitive development of infants 3 to 15 months old reared in institutional care (N = 75). Their development was compared with that of infants in a biological family group (N = 65). In Study II, infants' cognitive development in institutional care (N = 63) was compared with that of infants reared in low-socioeconomic status (SES) family environments (N = 60) at one-time point. The moderating role of temperament was also examined in both Study I and Study II. Study III examined the association between hair cortisol levels of the infants, SES levels of their families, cognitive development, and temperament. Findings from Study I showed that infants in institutional care had lower cognitive development in wave 1, and they could not catch up with their age-mates in family groups in wave 3. Study II showed that infants with low levels of falling reactivity had lower attention skills than infants in the low-SES family group. However, there was no group difference for infants with high levels of falling reactivity. According to the findings in Study III, a mediating role of hair cortisol was not found, but infants' temperament significantly moderated the effects of SES on infants' hair cortisol levels.