The chapters in this book are based on papers presented at the 23rd Carnegie Mellon Symposia on Cognition, held in Pittsburgh, June, 1990. This symposium was an exciting event. Speaker after speaker presented new discoveries about infants' visual perception in areas ranging from sensory processes to visual cognition. It was apparent from the talks that this field is continuing to make significant progress in understanding the infant's perceptual world.
Several advances have come from the development of new methods for exploring infant perception and cognition that have brought new empirical findings. Outstanding examples of these advances can be seen throughout this volume. Teller and Lindsey describe the "motion-nulling" technique that has allowed them to make precise measurements of infants' chromatic discriminations. Haith presents the innovative method that he has used to investigate infants' expectations about future events. Baillargeon describes the methods she has used to reveal young infants' object permanence. Kellman reviews a number of methods that led to discoveries about infants' object perception abilities; and Arterberry, Craton, and Yonas present new methods that they developed for studying infants' perception of object properties that are specified by motion.
Advances have also been made in understanding the mechanisms underlying perceptual development. Banks and Shannon report findings from "ideal observer" models indicating that immaturities in the retina are a major cause of newborns' poor visual acuity, contrast sensitivity, and chromatic vision. Aslin describes simulations that shed light on the processes involved in the development of accurate saccadic eye movements. Held discusses evidence that de