Visual imagination — or rather, the lack of it — can be verified by measuring pupil dilation, thereby providing the first physiological evidence of aphantasia, new research shows.
The study, led by researchers from UNSW Sydney and published in eLife, found that the pupils of people with aphantasia did not respond when asked to imagine dark and light objects, while those without aphantasia did.
To first gauge the pupillary reflex of non-aphantasic people, the researchers sought 42 study participants, self-reported as having a visual imagination, and fitted them with glasses to track their eye movements and pupil sizes.
Participants were then exposed to bright or dark shapes against a grey background, which predictably evoked pupillary constriction in response to bright shapes (comparable to looking up at a bright sky) and pupillary dilation in response to dark shapes (after…
