Environmental Contributions to Adolescent Delinquency: A Fresh Look at the Shared Environment

Few genetically-informative studies have attempted to explicitly identify the shared environmental (i.e., those environmental influences that contribute to sibling similarity) factors now known to contribute to adolescent delinquency. The current study therefore examined whether the parent-child relationship served as one source of these shared environmental influences. Participants were 610 adoptive and biological families from the Sibling Interaction and Behavior Study (SIBS). Parents and adolescents reported on their parent-child conflict and parental involvement with child, and adolescents reported on their own delinquent behaviors. We employed structural equation modeling and supplementary multilevel modeling, finding consistent evidence that the association between delinquency and the parent-child relationship is at least partially shared environmental in origin. Such findings provide an important extension of previous twin studies, as they suggest that passive genotype-environment correlations do not explain earlier findings of shared environmental influences on this association.     

Formal Schooling Influences Two- but Not Three-Dimensional Naming Skills

The modulatory influence of literacy on the cognitive system of the human brain has been indicated in behavioral, neuroanatomic, and functional neuroimaging studies. In this study we explored the functional consequences of formal education and the acquisition of an alphabetic written language on two- and three-dimensional visual naming. The results show that illiterate subjects perform significantly worse on immediate naming of two-dimensional representations of common everyday objects compared to literate subjects, both in terms of accuracy and reaction times. In contrast, there was no significant difference when the subjects named the corresponding real objects. The results suggest that formal education and learning to read and to write modulate the cognitive process involved in processing two- but not three-dimensional representations of common everyday objects. Both the results of the reaction time and the error pattern analyses can be interpreted as indicating that the major influence of literacy affects the visual system or the interaction between the visual and the language systems. We suggest that the visual system in a wide sense and/or the interface between the visual and the language system are differently formatted in literate and illiterate subjects. In other words, we hypothesize that the pattern of interactions in the functional-anatomical networks subserving visual naming, that is, the interactions within and between the visual and language processing networks, differ in literate and illiterate subjects.