A parent's interaction with their child during infancy creates an internal working model of attachment, which is the development of expectations that a child has for future relationships and interactions based on the interactions they had during infancy with their caregiver. If an adolescent continues to have a secure attachment with their caregiver, they are more likely to talk to their guardian about their problems and concerns, have stronger interpersonal relationships with friends and significant others, and also have a higher self esteem. Parents continue a secure attachment through adolescence by means of expressing understanding, having good communication skills, and allowing their child to safely begin to do things independently. Many of these theories of parenting styles are almost entirely based on evidence from high income countries, especially the USA. However, there are many fundamental differences in child development between high and low income countries, due to differences in parenting styles and practices. For instance, in sub-Saharan Africa children are likely to have more than one main care giver, to acquire language in a bilingual environment, and to play in mixed aged peer groups. However, when comparing African American caregiving among lower, middle, and upper socioeconomic families, the number of non-parental caregivers decreases as economic resources increase. In addition, international studies have found Chinese parents to be more concerned with impulse control, which may explain the greater use of authoritarian style as compared to U.S. parents. Thus, social values and norms within a culture influence the choice of parenting style that will help the child conform to cultural expectations. There is evidence to suggest cultural differences in the way children respond to parenting practices. In particular, there is ongoing debate surrounding physical discipline and corporal punishment of children. with some authors suggesting it is less harmful in ethnic groups or countries where it is culturally normative, such as several low income countries, where the prevalence rate remains high. Lansford "et al" (2004) reported harsh parenting was associated with more externalising behaviours in European American compared with African American adolescents. Resolving these issues is important in assessing the transferability of parenting interventions across cultures and from high to low income countries in order to improve child development and health outcomes. Some parenting styles correlate with positive outcomes across cultures, while other parenting styles correlate with outcomes that are specific to one culture. For example, authoritative parenting is related to positive self-esteem and academic outcomes for both Chinese and European American adolescents, but the positive effects of the “ethnic minority” parenting style are specific to Chinese adolescents. There is also evidence to suggest that there is not only cultural variation, but variations across settings within a culture.