WISC-R factor structures for diagnosed learning disabled Navajo and Papago children

WISC-R factor structures (Principal Factor Analysis-Varimax rotation) were compared for previously diagnosed samples of learning disabled Navajo and Papago children. Both two- and three-factor solutions were analyzed, utilizing coefficients of congruence. Both groups were similar in terms of proportion of common factor variance accounted for by a general factor, and the Verbal-Performance distinction was demonstrated in both groups.     

Origins of individual differences in imitation: links with language, pretend play, and socially insightful behavior in two-year-old twins

Imitation, vocabulary, pretend play, and socially insightful behavior were investigated in 5,206 same- and opposite-sex 2-year-old twin pairs in the United Kingdom. Individual differences in imitative ability were due to modest heritability (30%), while environmental factors shared between twins (42%) and unique to each twin (28%) also made significant contributions to the variance. Imitation correlated significantly, although modestly, with vocabulary, pretend play, and socially insightful behavior, and the strongest relationship was with vocabulary. A model that represented the covariance between the variables as being due to correlated latent genetic and environmental factors fitted the data well, with shared environmental factors influencing most of the covariance. Parents who encourage imitation may also tend to foster the development of language, pretence, and socially insightful behavior.     

How Nonemployer Firms Stage-Manage Ad Hoc Collaboration: An Activity Theory Analysis

Nonemployer firms—firms with no employees—present themselves as larger, more stable firms to take on clients’ projects. They then achieve these projects by recruiting subcontractors, guiding subcontractors’ interactions with clients, and coordinating subcontractors to protect their team performance for the client. Using fourth-generation activity theory, I examine how these firms stage-manage their ad hoc collaborations. I conclude by describing the implications for further developing fourth-generation activity theory to study such instances of knowledge work.