Reading performance and verbal short-term memory: A twin study of reciprocal causation

Abstract

Although a significant relationship between reading performance and verbal short-term memory (VSTM) has been well documented, the etiology of this relationship has not been fully explored. In the study presented here, the genetic and environmental causes of the phenotypic association between reading and VSTM were analyzed using twin data from the Colorado Reading Project. Results of bivariate behavioral genetic analyses indicate that both reading ability and VSTM are highly heritable, and that a substantial proportion of their phenotypic correlation is due to common genetic influences. Moreover, results of analyses of direction of causation suggest that differences in reading performance (or reading component processes) may influence performance on VSTM tasks, but that differences in VSTM are not an important cause of variation in reading performance. However, the possibility of a common cause of both reading performance and VSTM is not precluded.