Preschoolers did use certain aspects of the "child-directed speech" register: they addressed their infant siblings with a high pitch, with relatively short utterances, and with many directives and self-repetitions. However, linguistic interactions of preschool-age siblings and infants were different from those of mothers and infants in several…

Investigates differences in the language learning environments of six twin pairs and 12 singleton toddlers (all firstborn) with special reference to pragamatic factors that might be expected to differ in dyadic and triadic interactive situations. (HOD)