Action in the eye of the beholder: anticipatory gaze strategies for manual object interaction

Our eyes typically anticipate the next action module in a sequence, by targeting the relevant object for the following step. Yet, how the final goal, or the way we intend to achieve it, is reflected in the early visual exploration of each object has been less investigated. In a series of experiments we considered how scan paths on real-world objects would be affected by different factors such as task, object orientation, familiarity, or low-level saliency, hence revealing which components can account for fixation target selection during eye-hand coordination. In each experiment, the fixation distribution differed significantly depending on the final task (e.g. lifting vs. opening). Already from the second fixation prior to reaching the object the eyes targeted the task-relevant regions and these significantly correlated with salient features like oriented edges. Familiarity had a significant effect when different tools were used as stimuli, with more fixations concentrating on the active end of unfamiliar tools. Object orientation (upright or inverse) and anticipation of the final comfort state determined the height of the fixations on the objects. Scan paths dynamics, thus, reveal how action is planned, offering indirect insight in the structuring of complex behaviour and the understanding of how task and affordance perception relates to motor control.