Educational technology research often focuses on the development and implementation of tools for learning. The efficacy of tool development and implementation is regarded as successful if learning outcomes demonstrate an overall improvement. Studies in educational technology also examine the impact or effect of technologies on the learner. The goal of the present study was to determine if cognitive load would be manifested in a measurable physiological response. The present study examined the physiological impact of learning with static and dynamic images by measuring changes in mean cerebral blood velocity (CBV) of the right middle cerebral artery. It was determined that spatial ability has the greatest effect on changes in cerebral blood velocity and learner performance using complex images. Further, this study examined the relationship between perceived mental effort and changes in cerebral blood velocity in high and low spatial ability groups. It was determined that the while the relationships between changes in CBV and high and low spatial ability are weak, the direction of the relationships suggests a possible interaction that warrants further investigation. The findings from the present study show that spatial ability is a variable that impacts cognitive load. However, measuring specific elements of cognitive load is a challenge as they likely occur simultaneously during learning and can be difficult to isolate for investigative purposes.