The unique advantages of 2D and 3D display systems are not yet entirely clear. The choice of display system designers select often is dependent on how users are intended to interact with the display. A 2D display is beneficial when a user needs to make judgments on positioning. On the other hand, a 3D display may be best suited for providing an understanding of the shape of an object or scene. The benefits of 2D and 3D displays were examined during three experimental tasks. The first task was a classic mental rotation task that utilized 2D and 3D objects and required participants to judge whether pairs of objects were identical or different. The other tasks were replications of a published comparison of 2D versus 3D images. The second task required participants to make judgments on 2D and 3D maps based on altitude. The third task required participants to utilize 2D maps to identify 3D terrain renderings. Thirty undergraduate students from San Diego State University participated in the study. Each participant completed a single 60-minute session and responded to all three tasks. The study incorporated eye tracking in order to examine which features of the images the participants were looking at as they performed the tasks. Additionally, pupil data were used to examine levels of cognitive workload during the tasks. It was hypothesized that the 2D displays would lead to quicker and more accurate judgments than 3D displays for the mental rotation and map tasks. It was also hypothesized that the cognitive workload generated with 2D displays would be significantly lower than that generated with the 3D displays. The data revealed significant differences in task performance, F(2,25) = 186.108, p < .001, and in cognitive workload across tasks, F(2,25) = 3.9, p = .034. Observed cognitive workload was higher for the 2D displays than for the 3D displays, F(1,26) = 18.571, p < .001. The findings supported the hypothesis that 2D was best for decision making when dealing with relative position tasks. In comparison, 3D was best used with making shape perception decisions. These findings will assist human factors engineers and system designers in selecting the proper image or display based upon the task that the intended user will be completing. Overall, as technology within the 3D display realm continues to grow, researchers must continue to investigate the best uses for the technology while seeking to uncover and understand the best methods of implementing the technology.