Picture this: what if, when asked to construct a “mental picture” of something, you simply couldn’t? For sufferers of aphantasia, not only is this request impossible, it doesn’t even make sense. Though it has long been considered a given that all humans possess the capacity for visual imagination—to the extent that no one has even thought to truly question it—recent research suggests that's not true.

In the June 2015 issue of Cortex, an international peer-reviewed scientific journal, University of Exeter researcher Adam Zeman and co-authors Michaela Dewar and Sergio Della Sala assign a name to the previously unstudied phenomenon of not being able to see things in one’s own head. The root, “phantasia,” comes from Aristotle’s classical term for the mind’s ability to conjure up images; aphantasia, then is the absence of such an ability. Zeman and Della Sala had previously investigated a singular case of such an inability in 2005, but their newest findings indicate that there’s more than just one.

The first subject of the aphantasia study approached the scientists, not the other way around. MX, as the man is referred to in the literature, was a 65-year-old retired building inspector who scheduled an appointment with neurologist when he realized that after a lifetime of seeing exceptionally detailed images in his mind, he had suddenly gone blind on the inside. Zeman, a neurologist, and Della Sala, a cognitive neuroscientist, had no immediate solutions for MX’s plight, but they saw a rare opportunity to test some of science’s most fundamental speculations about the relationship between vision and imagination.

In all other respects, MX was determined to be a normal man. Successful in his past career, no previous trauma, high IQ, good memory, functioning vision—no different than the other 10 male architects around the age of 60 the researchers recruited as a comparison group. He could describe without difficulty familiar landmarks around the city of Edinburgh, he could recall the shade of Prime Minister Tony Blair’s eyes, and he could determine which letters of the alphabet do or do not have a low-hanging tail (for example, ‘g’ and ‘j’). However, he couldn’t “see” any of these things. His ratings on a test called the Vividness of Imagery Questionnaire were the absolute lowest possible, and brain scans showed that parts of the control group’s minds that were activated when asked to visualize certain famous faces were dormant in MX’s. Somehow, MX was processing visual imagery without seeing.

After the initial articles on MX were published, reports of similar cases began to surface. According to Zeman, a number of email respondents reported being unable to picture a sunrise, but were somehow able to make an accurate count of the windows in their home without moving a muscle. However, these new subjects differed significantly from MX in one way: while his symptoms had manifested suddenly after a routine surgery to treat his blocked coronary arteries, these apparent aphantasia sufferers had never in their lives known what it was like to have a visual imagination. 25-year-old Canadian student Thomas Ebermeyer reported that he had long gone unaware of his own deficit until his girlfriend recalled the details of a mutual friend’s outfit from a year before, and he realized for the first time that seeing pictures in one’s mind was the norm; he was the outlier. 

By Zeman’s early estimation, aphantasia remains a “moderately rare” condition, but nonetheless holds fascinating implications for the study of sight, mind, and memory. There may be some connection to “blindsight,” in which those who have lost the physical ability to see are often, for example, somehow able to navigate a crowded room, despite their own doubt that such a thing should be possible. There’s certainly more work to be done on the subject, but in the meantime, there is at least a name for it.