title: Predicting the outcomes of physical events: two-year-olds fail to reveal knowledge of solidity and support.
abstract: Two-year-olds' (N = 153) knowledge of solidity was tested in four search tasks adapted from infant looking-time experiments. In Experiment 1, 2-year-olds failed to search in the correct location for a falling ball after a hidden shelf that blocked its trajectory had been inserted in the apparatus. Experiment 2 extended this finding by showing that 2-year-olds failed to take into account the effects of either removing or inserting a shelf in their search for a toy dropped behind a screen. Experiment 3 examined sensitivity to the constraint provided by a solid barrier on horizontal motion. In all three experiments, 2-year-old children searched initially at the location where they saw the object during familiarization. Experiment 4, using multiple test trials but no familiarization to a pretest location, also showed that 2-year-olds failed to take the presence or absence of a barrier into account when planning where to search for a toy they had seen dropped behind a screen. In all of these studies, 2-year-olds showed no evidence of representing solidity and support constraints on the trajectories of falling objects. Experiments 1 and 3 also included 2 1/2-year-olds (N = 31), who succeeded on these search tasks. The implications of the poor performance of 2-year-olds, in the face of success by very young infants on looking-time measures of sensitivity to similar constraints on object motion, are discussed.
authors.affiliation: Department of Experimental Psychology, University of Bristol, UK. bruce.hood@bris.ac.uk
authors.forename: B
authors.initials: B
authors.lastname: Hood
authors.forename: S
authors.initials: S
authors.lastname: Carey
authors.forename: S
authors.initials: S
authors.lastname: Prasada
mesh_terms: D001288:Attention; D002675:Child, Preschool; D003210:Concept Formation; D005260:Female; D005556:Form Perception; D006801:Humans; D007223:Infant; D008297:Male; D009039:Motion Perception; D009949:Orientation; D011340:Problem Solving; D011601:Psychophysics