Eye-tracking system

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When people view a scene or do any other visual processing, their eyes move systematically, briefly fixating a particular location and then quickly shifting to a new location.  Consequently, the pattern of eye fixations during task performance provides crucial information about moment by moment changes in mental operations.  For example, when an observer views a picture of a barnyard scene that includes an octopus near the barn door, the observer's eyes quickly move to that anomalous object.  That movement indicates that the observer has detected an anomaly and that attention has shifted to the relevant location.  The equipment funded by this grant will enable detailed tracking of the sequence of eye movements made by human observers and measurement of each eye fixation duration.  The equipment will be used in three lines of investigation.  (1) Learn how knowledge about hand actions contributes to identifying manipulable objects (e.g., tools) or understanding sentences referring to those objects.  For example, tracking eye fixations directed toward a display showing four different hand shapes will provide information about which hand actions are activated while listening to a sentence like "Joe used the calculator".  This work will improve our understanding of neurological deficits associated with identification and manipulation of objects.  (2) Understand processes that control rapid shifting between different tasks requiring selection of a target visual stimulus from among a set of competing stimuli.  For example, in a laboratory variant of modern "heads-up" displays, a printed word is superimposed on a line-drawing of an object and observers are cued either to read the word or identify the object.  Switching between these tasks is difficult and eye movement patterns will to provide information about how successful task switches can be made more efficiently.  (3) Assess the influence of memory for previously viewed natural scenes on the visual inspection of a repeated presentation of those scenes, helping to determine, for example, how changes in scenes can be efficiently detected.  These applications of eye-tracking methods will provide new insights into basic cognitive operations that govern successful interaction with the environment.