In this study, we simulated a military mounted environment and conducted an experiment to examine the workload and performance of the combined position of gunner and robotic operator and how individual difference factors such as perceived attentional control and spatial ability were related to the task performance. Results showed that gunner's target detection performance degraded significantly when he or she had to concurrently monitor, manage, or teleoperate an unmanned ground vehicle compared to the gunnery-single task condition. Those with higher spatial ability performed significantly better than those with lower spatial ability. Participants with higher perceived attentional control performed better on a concurrent communication task in the more challenging robotic task conditions. Participants' perceived attentional control was negatively correlated with the severity of their simulator sickness but not with their perceived workload.