Tiffany C. Wu¹, John K. Tsotsos¹; ¹York University

Common visual search paradigms conducted on 2D screens with passive observation do not capture the full breadth and reality of eye and head movements used in real-world search. One is not presented with an image in real-world search; one must determine which images to acquire and in what order using relevant eye, head, and body movements. To investigate viewpoint selection and the role of fixation in active observation, an active visual search task was conducted in a controlled real-world environment. The scene was a physical 3x4m space furnished with tables and wire cages. Stimuli were miniature everyday objects, scattered in various orientations on the tables and cages. Observers moved freely, untethered, to search for a target object, and their eye and head movements, reaction time, and accuracy, were synchronized and measured over 12 trials each. Resulting eye and head movement data naturally seemed divided into “environment”, “look-at”, and “target look-at” fixations. “Look-at” refers to fixations viewing tables or cages with stimuli in view, “target look-at” refers to fixations viewing the target object, and “environment” covers all other fixations. Interestingly, subjects became more efficient at searching with successive target present trials, particularly in the number of look-at fixations. Target look-at fixations were also significantly longer than other fixations. Finally, we discovered that environment fixations often occur between look-at’s while a subject is navigating to a different location to continue their search. This suggests a clear distinction in the role between look-at fixations and environment fixations - one for searching through stimuli, and one for searching and navigating through the environment to achieve the next viewpoint. These results emphasize the importance of conducting search and other visual tasks in the real world, in order to capture the nuances of eye and head movement and strategies not otherwise found from a 2D paradigm.

Acknowledgements: This research was supported by the Canada Research Chairs Program (950-231659), and the Natural Sciences and Engineering Research Council of Canada (RGPIN-2022-04606).