Automated Corneal-Reflection Eye Tracking in Infancy: Methodological Developments and Applications to Cognition.

Since the mid-1800s, experimental psychologists have been using eye movements and gaze direction to make inferences about perception and cognition in adults (Müller, 1826, cited in Boring, 1942). In the past 175 years, these oculomotor measures have been refined (see Kowler, 1990) and used to address similar questions in infants (see Aslin, 1985, 1987; Branson, 1982; Haith, 1980; Maurer, 1975). The general rationale for relying on these visual behaviors is that where one is looking is closely tied to what one is seeing. This is not to deny the fact that we can detect visual stimuli in the peripheral visual field, but rather that there is a bias to attend to and process information primarily when it is located in the central portion of the retina. Thus, although the direction of gaze is not perfectly correlated with the uptake of visual information (e.g., as in a blank stare or a covert shift of attention), there is a strong presumption that the direction of gaze can provide important information about visual stimuli even in newborn infants (Haith, 1966; Salapatek, 1968; Salapatek & Kessen, 1966).