Abstract
GOAL: Perceptual grouping has often been investigated by asking participants to indicate the perceived grouping for stimuli presented at visual fixation. This method of research is unlike how we generally perceive the world, in which we make eye movements to peripheral stimuli for further processing. In this study we therefore examined the influence of perceptual grouping on different properties of goal-directed eye movements. METHOD: In three experiments, participants were instructed to make eye movements from a central fixation symbol to a peripherally presented target (4 to 6 deg), embedded in a background of dots. When the target was presented, for the experimental conditions, the background dots shifted position to form a circle (diameter=3.5 deg) left or right of fixation. In the control condition the dots formed two circles located on either side of fixation or no circle (baseline). Three aspects of eye movements were investigated: Response times, the curvature of the saccade trajectories and landing sites. RESULTS: Based on results from 10-12 subjects we found that response times were faster when a circle emerged around the target compared to when no circle appeared or when the circle appeared on the other side of fixation. Saccade trajectories to targets presented above and below fixation were not influenced by circles left and right of fixation except when the target was above the fixation and the circle was presented near the fixation (at 3 deg). Saccade landing sites were shifted towards the center of the circles when the target was presented inside a circle for leftward, but not rightward saccades. Together these findings suggest that perceptual grouping influences target directed eye movements, but the effects strongly depend on the location of the perceptual group with respect to the target of saccade.
Meeting abstract presented at VSS 2012