Compared comprehension of novel communicative signs to assist 2.5- and 3-year-old humans, chimpanzees, and orangutans find hidden objects during a hiding-finding game. Found that children at both ages performed above chance with all signs. No ape performed above chance for any signs not known before the experiment despite three times as many…

Addressing methodological limitations, Study One compared parent-child interactions of normal and language-delayed children; Study Two investigated whether mothers adjust the length of their utterances to the child's ability to comprehend or to produce language; Study Three probed interactional variables associated with variations in the…

This document reviews a number of recent studies written in French that investigate the nature of communication between 2-year-old infants and others. The review includes three parts. The first part focuses on studies aiming to constitute a behavioral catalog of the child. Characteristically, these studies offer a posteriori interpretations of…