The Influence of Movement Costs on Search Behaviour
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Humans regularly search their environment for an object to grasp through movements of the eye, head, and body. While search behaviour in humans has been well-studied, there has been little work which has investigated if the movement costs associated with searching influence where we search. While it has been shown that people attempt to minimize movement costs in other sensorimotor tasks, it is unclear to what extent people minimize these costs when making decisions of where to search for a target object. This thesis investigated whether people attempt to minimize both the biomechanical effort and time associated with searching for, and reaching to, target objects. The three studies contained in this thesis had participants search an environment for a target among distractors through either movements of the hand or eye. We manipulated the costs associated with searching, or reaching, by increasing the effort or time it took to search or reach to particular locations of the search environment. In the first study, we conducted a series of experiments to test the influence of movement effort and time on both visual and manual search. We found that visual search was influenced by time, but not effort associated with searching, with manual search being influenced by both time and effort costs. In the second study, we showed that participants are more influenced by movement time and effort costs during visual search when the costs are specified by visual information present in the search space. In the third study, we showed that participants are capable of minimizing movement effort during manual search after learning to associate the effort involved in search to visual features of potential target objects. Together, these studies are the first to directly reveal the influence of movement costs on search behaviour, reinforcing the view of search as a complex sensorimotor behaviour.