In the C-not-B task, 2.5-year-old children tend to look for an object in a location to which the hiding agent moved his hand (C) after moving an object from A to B. In three experiments, the authors investigated the nature of the constraints underlying toddlers' performance in this task. In Experiment 1, 2.5-year-olds were tested in a new version…

Three experiments investigated changes from 15 to 30 months of age in children's (N = 114) mastery of relations between an object and an aperture, supporting surface, or form. When choosing between objects to insert into an aperture, older children selected objects of an appropriate size and shape, but younger children showed little selectivity.…

Previous research has shown that young children have difficulty searching for a hidden object whose location depends on the position of a partly visible physical barrier. Across four experiments, we tested whether children's search errors are affected by two variables that influence adults' object-directed attention: object boundaries and…