Pupil size is thought to be controled by the [[LC-NE system]] see Cohen<ref>Eldar, Eran, Jonathan D Cohen & Yael Niv. 2013. The effects of neural gain on attention and learning. Nature Neuroscience. Published online June 16, 2013 doi:10.1038/nn.3428([http://blogs.princeton.edu/research/2013/07/11/pupil-study-reveals-learning-styles-brain-activity-nature-neuroscience/ summery])</ref>and Jepma & Nieuwenhuis<ref>[http://www.sandernieuwenhuis.nl/pdfs/JepmaNieuwenhuis_JoCN.pdf Marieke Jepma and Sander Nieuwenhuis, 2011, Pupil Diameter Predicts Changes in thev Exploration – Exploitation Trade-off: Evidence for the Adaptive Gain Theory, Jurnal of Cognitive Neuroscience 23:7, pp. 1587-1596]</ref>