A surveyor's sudden blindness
In 2005, a 65-year-old man known in scientific literature as MX underwent a minor heart procedure. Soon after, he contacted Adam Zeman, a neurologist at the University of Exeter, with a strange complaint: he had lost his ability to form mental images. He could still recognize his family, describe his home, and identify famous landmarks from memory, but he could no longer picture them in his mind's eye. The internal cinema of his imagination had gone dark. Even his dreams became non-visual.
Zeman and his team studied MX using functional magnetic resonance imaging (fMRI) to observe his brain activity. When they showed him pictures of famous faces, the visual processing regions in his brain lit up as expected. When they asked him to simply imagine those same faces, those higher-level visual areas remained quiet. His case, published in 2010, was the first modern, detailed study of what is now called acquired aphantasia. It demonstrated that the brain network for recognizing a face is different from the one used to voluntarily visualize it.
Naming a hidden phenomenon
The story of Patient MX, popularized in a 2015 magazine article, prompted an unexpected response. Zeman’s inbox filled with emails from people who had read about MX and recognized their own experience, but with one major difference. They had never been able to form mental images. This lifelong condition had previously been noted by Francis Galton as early as 1880 but had remained largely unstudied.
This influx of reports led Zeman's team to formally describe the condition. They named it congenital aphantasia, from the Greek words a (without) and phantasia (imagination). Their 2015 paper in the journal Cortex showed it as a specific variation in human experience. Studies suggest that aphantasia affects approximately 0.9% to 2% of the population. On the other side of the spectrum is hyperphantasia, the experience of vivid, photo-realistic mental imagery, which may affect up to 6.1% of people.
The primary tool for assessing these differences is the Vividness of Visual Imagery Questionnaire (VVIQ), a 16-item survey developed by British psychologist David Marks in 1973. The research spurred by the discovery in Devon continues to reveal how differently human minds can operate, clarifying the distinction between conceptual knowledge and sensory imagination.