Abstract
Introduction: A critical question in multitarget visual foraging concerns the factors driving the next target selection. Recent theories propose that target selection is achieved in two steps: identification of a set of candidates (through eye movements), and selection of the best option among these candidates (based on internal biases toward proximity, priming or value). However, the role of eye movements in visual foraging is poorly understood. We tested whether eye movements are required for identifying a set of candidates, and whether disabling eye movements during foraging could affect target selection. Methods: We asked 24 participants to perform four foraging tasks differing by selection modality and target value. During gaze-foraging, participants had to accurately fixate the targets to select them and could not anticipate the next target with their eye-gaze. During mouse-foraging, participants selected the targets with mouse clicks and were free to move their eyes. We moreover manipulated target proximity and value, where some targets yielded more points than others. The task was to obtain a prespecified number of points as quickly as possible. Results: The results confirmed that target value and proximity affect all aspects of foraging behavior, from manual reaction times to oculomotor dynamics. Importantly, although the effect of target value was strong for all observers, individual differences were notable, confirming the existence of internal biases towards priming, proximity and value. Moreover, although the results show important differences in oculomotor dynamics between mouse- and gaze-foraging, there were no differences in search strategy (e.g., order of target selections) between selection modalities. Conclusions: Our findings importantly suggest that overt orienting is not necessary for identifying a set of candidates, but that it may be involved in the selection of the best option among these candidates. Our results could therefore provide fundamental information for theoretical conceptions of attentional selection.