Poster Session: Chromatic and luminance contrast adaptation measured using pupillometry and SSVEP.

Previous evidence suggests both chromatic and luminance contrast adaptation reduces contrast sensitivity in the post-adaptation period. This effect is chromatically-tuned: adaptation is greatest when the adaptor and probe lie on the same chromatic axis. Previous fMRI data from our lab also suggests S-cone adaptation results in a paradoxical increase in post-stimulus BOLD signal. Here, we use SSVEP and pupillometry to ask whether we can measure physiological correlates of this adaptation. SSVEPs were recorded from V1 using a canonical EEG template (Poncet & Ales, 2023) and pupil diameter was measured using an EyeLink1000 for 21 participants. Stimuli were contrast-reversing chromatic or luminance disks (5Hz, 20° visual angle) presented during a 7s preprobe, 30s adaptation, and 7s probe period. The preprobe and probe were always the same chromaticity at 50% of the adapting contrast. Stimuli were L+M or S-cone isolating with four conditions overall (S/L+M) * (adapt/probe). Both pupils and V1 show an increase in size and response respectively after adaptation, contradicting the idea that adaptation reduces contrast sensitivity. Pupil data showed L+M adaptation increases pupil diameter more for L+M than S probe, with S adaptation having little effect. V1 showed an overall effect of adaptation, but no differences across conditions suggesting that the pupils are more sensitive to chromaticity in adaptation, while cortex shows adaptation independent of chromaticity.