Nature, Nurture, and the Transition to Early Adolescence

Transcription

1 University Press Scholarship Online You are looking at 1-10 of 12 items for: keywords : Colorado Adoption Project Nature, Nurture, and the Transition to Early Adolescence Stephen A. Petrill, Robert Plomin, John C. DeFries, and John K. Hewitt (eds) Item type: book acprof:oso/ Some of the most intriguing issues in the study of cognitive, social, emotional, and physical development arise in the debate over nature versus nurture; a debate difficult to resolve because it is difficult to separate the respective contributions of genes and environment to development. The most powerful approach to this separation is through longitudinal adoption studies. The Colorado Adoption Project (CAP) is the only longitudinal adoption study in existence examining development continuously from birth to adolescence, which makes it a unique, powerful, and tremendously valuable resource. CAP is an ongoing assessment of 245 adopted children and 245 biological control children assessed from birth to early adolescence. This book is the fourth in a series describing CAP results. This latest volume, edited by four eminent researchers in developmental psychology, builds on the large body of research already generated by investigating the role of genes and environments on early adolescent development. Multivariate Parent-Offspring Analyses of Specific Cognitive Abilities Maricela Alarcón, Robert Plomin, Robin P. Corley, and John C. Defries acprof:oso/ During the last few decades, family, twin, and adoption designs have been used to assess the genetic and environmental etiologies of specific cognitive abilities (SCA). The largest family study of SCA was the Hawaii Family Study of Cognition, which included test data from 1,816 intact nuclear families. Measures of parent-offspring resemblance can only be Page 1 of 7

2 considered via upper-bound estimates of heritability. Thus, family studies can provide conclusive evidence for the familiarity of a trait, but not for its genetic etiology. In contrast, results obtained from twin studies can provide estimates of heritability. This chapter discusses the results of multivariate genetic analyses of Colorado Adoption Project (CAP) parentoffspring data at seven and twelve years of age, and compares them to those obtained by Rice et al. (1989) when the CAP children were only four years of age. The etiologies of individual differences for each of the four measures verbal, spatial, perceptual speed, and memory and their covariation were assessed by fitting a parent-offspring multivariate conditional path model to CAP specific cognitive abilities data. Memory Ability during Middle Childhood and Early Adolescence in the Colorado Adoption Project Stephen A. Petrill and Sally-Ann Rhea acprof:oso/ This chapter explores memory ability in the Colorado Adoption Project (CAP) at ages nine, ten, twelve, and fourteen. Although memory has been examined longitudinally in conjunction with other cognitive abilities, this chapter examines memory ability in CAP more systematically using isomorphic tests measured during the transition from middle childhood to adolescence. Given that heritability of memory may vary by the type of memory measure employed, the chapter first analyzes different aspects of memory through both phenotypic and univariate genetic analyses before exploring their longitudinal relationships. It is hypothesized in this chapter that like other cognitive abilities such as verbal ability, spatial ability, and perceptual speed, genes will be largely responsible for the similarity in memory across time while the non-shared environment will be largely responsible for the discrepancy between longitudinally assessed memory scores. The results show that the correlation between memory tests was driven almost completely by shared genetic factors while the discrepancy between memory tasks was influenced largely by the non-shared environment (and error). Page 2 of 7

3 Developmental Analysis of IQ E. G. Bishop, Stacey S. Cherny, and John K. Hewitt Page 3 of 7 acprof:oso/ This chapter describes some aspects of the development of general cognitive ability from infancy through the transition to early adolescence. This is done through analysis of data from the Colorado Adoption Project (CAP). The chapter focuses on the development of individual differences in general cognitive ability at ages one to twelve. The extent that phenotypic differences are correlated over time implies continuity in development; the extent that they are not correlated implies change. The relationship between genetic and environmental influences across time indicates the degree to which these processes of continuity and change are driven by genetic factors and by the environment. The structural equation modeling approach brings powerful methods to bear on the issue of behavioral development. The multivariate modeling approach has been used to explore the origins of covariation between cognitive ability and academic achievement. Genes or environments may be consistent in the nature of their influence during development. Alongside developmental continuity, gene expression, and the influence of the environment can change with age. Etiology of the Stability of Reading Performance from 7 to 12 Years of Age and Its Possible Mediation by IQ Sally J. Wadsworth and John C. Defries acprof:oso/ In addition to common genetic factors on reading ability at different ages, other variables may mediate the stability of individual differences in reading performance over time. For example, measures of reading performance are correlated with measures of general cognitive ability both phenotypically and genetically. Further, results of studies focusing on the etiology of stability of general and specific cognitive abilities provide evidence for substantial and significant genetic stability from age to age. This chapter presents the results of a study that assessed the etiology of stability of individual differences in reading performance

4 from age seven to age twelve, and its possible mediation by intelligence quotient (IQ), in a sample of related and unrelated sibling pairs tested in the Colorado Adoption Project. This chapter hypothesizes that the stability of reading performance may be mediated both phenotypically and genetically, at least in part, by IQ. Genetic Influences on Temperament in Early Adolescence: A Multimethod Perspective Jeffrey R. Gagne, Kimberly J. Saudino, and Stacey S. Cherny acprof:oso/ Although twin studies of infant and child temperament consistently yield evidence of moderate genetic influences, adoption studies do not. For example, in the Colorado Adoption Project (CAP), genetically related nonadoptive siblings were no more similar for parent-rated temperament than genetically unrelated adoptive siblings. However, most twin and adoption research exploring genetic factors underlying temperament during infancy and early childhood has relied on parent-rating scales, which may be susceptible to contrast effects wherein the differences between siblings may be exaggerated. Because contrast effects reduce the similarity of non-adoptive and adoptive siblings, adoption studies that use parent-rating measures may underestimate heritability. This chapter investigates changes in heritability across age and examines genetic and environmental factors underlying continuity and change in temperament during early adolescence in the CAP. To date, most of the research on continuity and change in temperament has focused on infancy and early childhood and suggests that genetic influences remain stable or increase with age. This study tested whether the patterns would hold true for a sample of early adolescents. Links between Temperament and Behavior Problems in Early Adolescence Stephanie Schmitz and Kimberly J. Saudino acprof:oso/ Page 4 of 7

5 There is growing interest in clinical and developmental psychology in the antecedents of problem behavior in children. One of the possible antecedents of problem behavior is temperament, in particular difficult temperament. Problem behavior in early and middle childhood involved both genetics and environmental factors. Rende (1993) tested correlations between different aspects of temperament in infancy and early childhood with problem behavior when the children were seven years old, utilizing data collected in the Colorado Adoption Project. The emotionality aspect of temperament was most consistently related to problem behavior at later ages while there were only sporadic relationships for activity, sociability and persistence. This chapter examines antecedents of problem behavior, as indicated by the Child Behavior Checklist and the Teacher Report Form, with ratings from the temperament domain. Twin, adoption, and genetically non-informative studies show phenotypic associations between temperament rated at prior age points and later aspects of problem behavior. Twin studies reported genetic and some shared-environmental correlations as underlying these associations. Conclusions Stephen A. Petrill, Robert Plomin, John C. Defries, and John K. Hewitt acprof:oso/ This book has analyzed data from the Colorado Adoption Project to determine the genetic and environment influences on several key aspects of adolescent development. This concluding chapter highlights some of the major findings and their implications for our understanding of development during the transition to early adolescence. In the past, behavioral genetic results typically have been interpreted in terms of how much genes and environments impact outcomes. More recently, the focus has shifted to applying behavioral genetic methods to address theoretically meaningful questions in developmental psychology to better understand the genetic architecture of development as well as the central role of the environment and gene-environment processes. Early adolescence is a time of immense average growth, and is a developmental period where individual differences are also important. Behavioral genetic methods examine how genes and environments shape the developmental trajectory of these individual differences. This chapter presents quantitative genetic analyses in four substantive Page 5 of 7

6 domains: cognitive ability and achievement, adjustment and behavior problems, mood and temperament, and the environment. The Developmental Trajectory of Genotype-Environment Correlation in Early Adolescence Erica L. Spotts and Jenae M. Neiderhiser acprof:oso/ Evidence for the presence of genotype-environment (GE) correlations has been accumulating in recent years. This chapter explores the developmental trajectory of GE correlation in early adolescence. A GE correlation is simply a correlation between a genotype and the environment to which the genotype is exposed. There are three ways that a genotype and an environment can be correlated: passively, evocatively, and actively. Passive GE correlation refers to the transmission of both genes and environment from parents to their children. Evocative GE correlation refers to environments that are evoked by the child's genotype, whereas active GE correlation occurs when children actively select environments that are correlated with their genotype. The present analysis integrates previous reports of GE correlation with new explorations using the most recent Colorado Adoption Project data to provide a larger picture of GE correlation from infancy to early adolescence. Stability and Change in Internalizing Problems in the Transition to Early Adolescence: Genetic and Environmental Influences Kirby Deater-Deckard and Shirley McGuire acprof:oso/ Internalizing problems in childhood and adolescence reflect a broad array of emotions, including feelings of sadness, loneliness, depression, anxiety, and somatic problems. Much research has focused on describing the prevalence, predictors, and stability of depressive illness in referred and clinically diagnosed groups of children. Another series of studies has focused on understanding the nature and correlates of individual Page 6 of 7

7 differences in internalizing symptoms in unselected community samples. The two approaches complement each other since the etiology of the extremes may be similar to the etiology of the full range of internalizing problems in the population. This approach is one component within the field of developmental psychopathology that emphasizes exploration of the links between the normal and abnormal in order to learn more about development. This chapter presents the results of a study that assessed the etiology of stability and change in several aspects of internalizing problems (loneliness, depression, and anxiety) in a community-based sample, the Colorado Adoption Project. Page 7 of 7