The similarity of siblings' attachments to their mother

Do siblings develop similar attachment relationships with their mother? Attachment theory suggests that brothers and sisters growing up in the same family are likely to relate in similar ways to their parents, at least when parental attachment representations and interactive styles remain stable across time. In the current study, sibling attachment data from three research groups (from Pennsylvania State University, Leiden University, and the University of Western Ontario) have been pooled to assemble a sufficiently large sample of observations (N = 138 sibling pairs) for a detailed comparison of sibling attachment relationships. Spacing between the births, differences in maternal sensitivity, and gender of siblings were examined as possible sources of concordance of nonconcordance. Attachment security (including disorganized attachment) of each sibling was assessed with the Strange Situation procedure between 12 and 14 months after birth. Maternal sensitivity was observed with the same rating scale in a laboratory play session in one of the studies and in home observations in the others. Sibling relationships were found to be significantly concordant when classified as secure/nonsecure (62% concordance, p < .01, 1-tailed, intraclass correlation = .23) but not when further subcategorized. Maternal insensitivity to both siblings (shared environment) was associated with concordance of sibling nonsecurity. Siblings of the same gender were more likely to form concordant relationships with their mother (68%; p < .01, 1-tailed, intraclass correlation = .37) than those of opposite gender. Same-sex sibling concordance was comparable to the concordance found for monozygotic twins in earlier studies. Genetic factors may, therefore, play a relatively small role in the development of attachment.     

Conceptual learning in relation to near and far transfer in the secondary school subject of economics

In this study we investigated the effects of two treatments supplementing students’ (16 to 18 years of age and in pre-university education) regular course in economics. One treatment, labelled concept treatment, aimed at the solidification of the students’ knowledge about economic concepts and their interrelations. The other treatment, labeled context treatment, aimed at the solidification of the connections between economic concepts and practical contexts. The aim of the study was to find out which treatment was most effective in meeting two demands that have been made by educators and advisory boards. The first demand is that students should gain competence in analysing practical problems from an economic perspective. The second demand is that students should be prepared for transfer of what they learned in the lessons to problems that are new to them.