Investigating the role of stimulus and goal driven factors in the guidance of eye movements

Three experiments investigated the influence and timing of various goal- and stimulus-driven factors on the guidance of eye movements in a simple visual search task. Participants were asked to detect the presence of an object of a given color from among various distractor objects that could share either the color or shape of the target object. The contrast of one or more objects was manipulated to investigate the influence of an irrelevant salience cue on the eye movements. A time dependant analysis showed that participants\u27 early eye movements were generally directed towards the upper left object in the display. The analysis further indicated that color then quickly became the primary guiding factor for the eye movements with salience and shape having minimal effects in early processing. Further analyses indicated that shape also influenced eye movement behavior, but largely to cancel eye movements to the target object and to end the trial without an eye movement. These analyses also indicated that shape was only processed when an object was attended because it had the target color. A model was developed and fit to the data of Experiment 1