THE GENERAL PROBLEM

Measurement of eye movements is a powerful tool for investigating perceptual and cognitive function in both infants and adults. Straightforwardly, eye movements provide a multifaceted measure of performance. For example, the location of fixa-tions, their duration, time of occurrence, and accuracy all are potentially revealing and often allow stronger inferences than measures such as percentage correct or re-action time. Another advantage is that eye movements are an implicit measure of performance and do not necessarily involve conscious processes. Indeed, they are often a more revealing measure than conscious report (Hayhoe, Bensinger, & Ballard, 1998). Although the mere presence of gaze at a particular location in the visual field does not reveal the variety of brain computations that might be operat-ing at that moment, the experimental context within which the fixation occurs of-ten provides critical information that allows powerful inferences. The articles in this thematic collection are excellent examples of this. EYE MOVEMENTS AND COGNITIVE PROCESSES