One interpretation proposed by the authors has to do with the shared top-down mechanisms between visual imagery and perception, where brain regions that interpret visual information process imaginary visuals in much the same way as actual visual data. However, perhaps the most interesting question posed by the study is how mental imagery could be driving involuntary pupil response to begin with. This adds another tool for researchers working to measure strength of mental imagery in further studies. "We are now close to an objective physiological test, like a blood test, to see if someone truly has it," says lead author of the study, psychologist Joel Pearson from UNSW Sydney.Īdditionally, researchers found that people who could imagine more vivid images showed greater pupil dilation. "Finally, we show that, as a group, there is no evidence of this pupil response in individuals without mental imagery (aphantasia)," they add.īecause 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. "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. 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. Individuals from both groups showed regular pupil dilation responses to both the light and dark images.īut then the researchers asked both groups to imagine the same images with their eyes open.
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. 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. More specifically, in a new study aphantasia could be detected based on pupil dilation response.