"Graspability" of Objects Affects Gaze Patterns During Perception and Action Tasks

When grasping an object, our gaze marks key positions to which the fingertips are directed. In contrast, eye fixations during perceptual tasks are typically concentrated on an object's centre of mass (COM). However, previous studies have typically required subjects to either grasp the object at predetermined sites or just look at computer-generated shapes "as a whole". In the current study, we investigated gaze fixations during a reaching and grasping task to symmetrical objects and compared these fixations with those made during a perceptual size estimation task using real (Experiment 1) and computer-generated objects (Experiment 2). Our results demonstrated similar gaze patterns in both perception and action to real objects. Participants first fixated a location towards the top edge of the object, consistent with index finger location during grasping, followed by a subsequent fixation towards the object's COM. In contrast, during the perceptual task to computer-generated objects, an opposite pattern in fixation locations was observed, where first fixations were closer to the COM, followed by a subsequent fixation towards the top edge. Even though differential fixation patterns were observed between studies, the area in which these fixations occurred, between the centre of the object and top edge, was the same in all tasks. These results demonstrate for the first time consistencies in fixation locations across both perception and action tasks, particularly when the same type of information (e.g. object size) is important for the completion of both tasks, with fixation locations increasing relative to the object's COM with increases in block height.