Figure 1: Schematic presentation of the testing protocol. With either a light sequence of blue-blue-blue or a sequence of blue-red-blue. The identical first and third blue light stimulations are termed the reference and test stimulus, respectively and the middle light stimulus is termed the intervening light exposure. Each light stimulus lasts 30 seconds and is separated by a 30 second dark period. Before presentation of the light stimulus sequence, the pupil is recorded for 10 seconds in darkness in order to obtain a baseline pupil size.