Why is instructional gesture ineffective in some contexts? And what is it about learners that predicts whether they will learn from gestures? This between-subjects linear measurement training study compares gesture instruction to two controls--operant action and transient action--in a diverse sample of first-grade students (N = 174, M[subscript…

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…