Référence bibliographique 
White, Elaine K., Tosto, Maria G., Malykh, Sergey B., Kiddle, Beatrix, Byrne, Brian, Brendgen, Mara, Tremblay, Richard E., Garon-Carrier, Gabrielle, Xinying, Li, Riglin, Lucy, Dionne, Ginette, Vitaro, Frank, Boivin, Michel et Kovas, Yulia. 2018. «Twin Classroom Dilemma: To Study Together or Separately? ». Developmental Psychology, vol. 54, no 7, p. 1244-1254.
«The aim of this study [is] to examine the average effect of classroom separation on school achievement, cognitive ability, and academic motivation; and if average effects were found, to further test whether twins taught separately perform more differently from each other than those taught together.» (p. 1251)
«The study addresses two main research questions: […] Are there average positive or negative effects on school achievement, cognitive ability, and academic motivation of twins associated with being in the same versus different classroom, and do the effects vary as a function of twins’ sex and/or zygosity and the timing of separation? […] Are twins taught in different classes more different than each other in achievement, cognitive ability, and academic motivation than are twins taught in the same class?» (p. 1247)
«The two representative samples taking part in the study are as follows: the U.K. Twins Early Development Study […], which provided data between ages 7 and 16 years from 8,705 twin pairs […], following exclusion of data from participants with medical issues and English spoken as a second-language and the Canadian French and/or English speaking Quebec Newborn Twin Study […], which provided data from 426 twin pairs […] between ages 7 and 12 years.» (p. 1247)
Type de traitement des données :
The «results show no sizable positive or negative average effect of separation on twins’ achievement, cognitive ability and motivation. The few effects found were weak and could stem from other factors rather than a real effect of classroom separation. These results suggest that in terms of academic achievement, cognitive ability and motivation, policymakers should not impose rigid guidelines for schools and parents to separate twin pairs during their education. The choice of whether to educate twin pairs together or separately should be up to parents, twins and teachers, in response to twins’ individual needs.» (p. 1253)