Aphantasia is a condition where some people can't see things in their mind. For a long time, aphantasia was only identified by people. We may be able to detect it in a different way.
The eyes have it. A new study has shown that aphantasia can be detected by the response of the pupils. 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.
A group of people with aphantasia were asked to view images with light and dark shapes on a gray background, while a group of people with regular visual imagination skills were asked to view images with light and dark shapes.
Both groups of individuals showed regular responses to the light and dark images.
Both groups were asked to imagine the same images. They found that the pupils of individuals with regular visual imagination would contract and expand, while the pupils of individuals with aphantasia did not.
The authors of the paper state that their results provide novel evidence that our pupils respond to the vividness and strength of a visual image being held in mind.
They show that there is no evidence of this response in individuals without mental imagery.
The study offers a new measure of aphantasia since it does not rely on self-report.
The lead author of the study says that they are close to an objective test like a blood test to see if someone really has it.
Researchers found that people who could imagine more vivid images had a greater dilated pupils. Another tool for researchers to measure the strength of mental imagery is added by this.
The most interesting question posed by the study is how mental imagery could be driving the response to it.
One interpretation proposed by the authors is that brain regions that interpret visual information process imaginary visuals in the same way as actual visual data.
The findings that the stronger or more vivid your mental pictures, the more perception-like they are, is supported by this case.
To make sure the participants with aphantasia were really trying to imagine the images in the study, they included an extra task, where they were asked to visualize four shapes simultaneously, instead of one.
Neuroscience researcher Lachlan Kay from the Future Minds Lab says that our pupils get larger when we are doing a more difficult task.
Imagining four objects at the same time is more difficult than imagining one. The pupils of those with aphantasia dilated when they imagined four shapes compared to one, but did not change based on whether the shapes were bright or dark.
Our brains can perform a lot of important functions thanks to the human ability to form mental images of visual content. We do it to retrieve information from our long and short-term memory, we do it when we are learning a language, and we do it when we navigate or remember where we have been.
The mental world for people with aphantasia is different than the world as a whole.
The study was published in a journal.
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