The Eyes Can Reveal if Someone Has Aphantasia – An Absence of Visuals in Their Mind
CONOR FEEHLY 25 APRIL 2022
Aphantasia is the strange condition where some people are unable to visualize images in their mind. For a long time, aphantasia could only be identified thanks to people's self-reported experiences. Now, we may finally have a way to detect it in a different way.
In this case, the eyes have it. More specifically, in a new study aphantasia could be detected based on pupil dilation response. When the human eye is exposed to bright light, our pupils contract, and when they are exposed to darkness they expand so as to let more light into the retina; however, it's also known our pupils can change size due to cognitive tasks.
Researchers in Australia tested two groups of participants; 42 in one group with self-reported regular visual imagination skills, and another group of 18 individuals with self-reported aphantasia were asked to view images with light and dark shapes on a gray background.
Individuals from both groups showed regular pupil dilation responses to both the light and dark images.
But then the researchers asked both groups to imagine the same images with their eyes open. Curiously, they found that the pupils of individuals with regular visual imagination would still contract and expand, while the pupils of individuals with aphantasia didn't change size to a significant level.
"Our results provide novel evidence that our pupils respond to the vividness and strength of a visual image being held in mind, the stronger and more vivid that image, the greater the pupillary light response," state the authors of the paper.
"Finally, we show that, as a group, there is no evidence of this pupil response in individuals without mental imagery (aphantasia)," they add.
Because the pupil's response to light is involuntary, the study offers a new unbiased measure of aphantasia, since this technique does not rely on self-report. ...