Pupil Dilation as an Index of Learning

Abstract

Physiological assessment of cognitive processes has become a topic of increased interest. The value of understanding and measuring brain function at work has the potential to improve performance. The emphasis of this paper is to discuss how pupil diameter can be applied to learning. The link between pupil diameter and task difficulty, or cognitive load, has been repeatedly demonstrated for the past 40 years. However there has been little work to date on measuring cognitive load during training or looking at how real time metrics of cognitive load could be used to adapt training. According to Cognitive Load Theory, cognitive load should be reduced as an individual learns a task and he/she relies more on long term memory than working memory. Ten participants completed a simulated unmanned aerial vehicle task in which they had to identify targets and report their direction of movement. There were three levels of increased difficulty. As expected, pupil diameter significantly dropped within each block as participants learned the task, and then increased again at the start of the next level of difficulty. The results suggest that pupil diameter may be a useful metric for assessing when an individual has transferred information into long term memory. Implications for how pupil diameter can be used to drive an adaptive training system are discussed.