Attentional and ocular movements.

Abstract

The relationship between eye movements and movements of attention was examined in a series of 6 experiments. A temporal order judgment technique was used to index attentional allocation. The results showed that endogenous movements of attention were slower than movements of the eyes and that the participants were able to hold attention at one location while executing an eye movement to another location. Under conditions of exogenous cueing, attention moved rapidly to the cued location, in advance of the eyes. These findings challenge the prevailing view that ocular movements must necessarily be preceded by a movement of The human visual system has two means by which to sample information from a scene, ocular and attentional. Ocular sampling involves movements of the eyes and consists of a series of fixations from one location to another. Attentional sampling has been described as a movement of an attentional spotlight (Posner, Snyder, & Davidson, 1980) or beam (Eriksen & Yeh, 1985) or as the repositioning of an attentional gradient (LaBerge & Brown, 1989). An important issue concerns the relationship between the ocular and the attentional systems and the manner in which the two systems interact. It is accepted that the ocular system does not constrain the attentional system insofar as attention can be moved in the visual field while the eyes remain fixated at one position. The extent to which attention constrains eye movements, however, has not been resolved. One possibility is that the eyes cannot be moved to an unattended location in the visual field; that is, prior to each saccade, attention must move ahead of the eyes to select the next fixation location. Another possibility is that eye movements can occur independently of attention such that the eyes can be moved to a location in the visual field that has not been targeted by attention. In the present research, we studied whether saccadic eye movements can occur independently