Eye movements and natural tasks in an extended environment

Eye movements can be thought of as a window onto pre-conscious thought. Patterns of visual fixations over time as well as space can reveal cognitive strategies that are not amenable to conscious control or verbalization. A spatial analysis of an eye movement trace usually emphasizes the role that eye movements have in moving the retinal image of an object of interest from the periphery to the fovea for closer inspection. It is generally believed that a sequence of fixations across a region of space builds up the perception of a high-resolution field of view everywhere. Recent studies have shown that this perception is largely illusory. The visual-perceptual system prefers to maintain a limited internal representation of physical objects in the world and uses the environment as an external source of information, accessing the information only at the time it is needed. The goal of this research effortwas to investigate the role that eye movements have in the performance of everyday tasks in a natural environment. A series of four experiments were conducted that represent an attempt to step away from the classical psychophysical approach of studying eye movements widiin the confines and contaol of the laboratory. There exists little precedence for this kind of approach, partly because past research efforts have emphasized a linear systemsmethod to render the analysis tractable, and partly because the technology that is required to perform these experiments has not existed until recently. The hardware that was developed by the Visual Perception Laboratory at RIT specifically addresses the portability concerns that are crucial for successfully studying eye movements during natural tasks in a non-linear extended environment. A model was developed to describe the temporal sequencing of eye movements in terms of a hierarchical structure of goal-oriented tasks, with individual fixations considered the lowest level of the hierarchy. The analysis gives evidence for the sequencing of eye movements based on a desire to maximize the efficiency of task performance over time by anticipating future activities. The purpose of this sequencing is to enhance interactionwith the world under conditions of limited memory representations rather than to create the perception of a high-resolution field of view.