Zachary Kelly¹, John Franchak¹; ¹University of California, Riverside

Search in the real world is three-dimensional, and thus requires the use of the head and body to help move the visual field around the environment. Previous research has established that increased cognitive load can alter movement of the eyes during search. Cognitive load also disrupts motor coordination in various tasks. However, it is unclear how cognitive load affects the eye, head, and body movements used to shift gaze during three-dimensional visual search. We gathered head-mounted eye-tracking data from 44 participants who searched an array of 27 images distributed across 3 separate walls in a 270º space and reported the number of images that matched a specified color-object type pairing. At the same time, participants completed a backwards counting task used to manipulate the level of cognitive load. Similar to past work, we found that as cognitive load increased, participants made fewer and longer looks at stimuli, and increased their rate of returning to look at previously viewed stimuli. In addition, we found that participants decreased the amount of head and body movements as cognitive load increased, evidenced by a decrease in wall switches (shifting the gaze from one wall to one of the other two walls). These findings suggest that when cognitive load was high, participants decreased their head and body movements in order to lessen the expenditure of cognitive resources spent on coordinating motor effort. This in combination with the changes in eye movements may suggest that visual search behavior in 3D is not only moderated by cognitive load, but the motor effort required to move the head and body.