In 2005, a 65-year-old retired building inspector paid a visit to the neurologist Dr. Adam Zeman at the University of Exeter Medical School. After a minor surgical procedure, the man — whom Dr. Zeman and his colleagues refer to as MX — suddenly realized he could no longer conjure images in his mind.
Dr. Zeman couldn’t find any description of such a condition in medical literature. But he found MX’s case intriguing. For decades, scientists had debated how the mind’s eye works, and how much we rely on it to store memories and to make plans for the future.
MX proved to have a good memory for a man of his age, and he performed well on problem-solving tests. His only unusual mental feature was an inability to see mental images.
Dr. Zeman and his colleagues then scanned MX’s brain as he performed certain tasks. First, MX looked at faces of famous people and named them. The scientists found that certain regions of his brain became active, the same ones that become active in other people who look at faces.
Then the scientists showed names to MX and asked him to picture their faces. In normal brains, some of those face-recognition regions again become active. In MX’s brain, none of them did.
Paradoxically, though, MX could answer questions that would seem to require a working mind’s eye. He could tell the scientists the color of Tony Blair’s eyes, for example, and name the letters of the alphabet that have low-hanging tails, like g and j. These tests suggested his brain used some alternate strategy to solve visual problems.
Indeed, researchers have discovered that certain people are unable to summon up mental images — it’s as if their mind’s eye is blind. In the month of June 2015, the condition received a name in the journal Cortex: aphantasia, based on the Greek word phantasia, which Greek philosopher and scientist Aristotle used to describe the power that presents visual imagery to our minds.
The scientists at the University of Exeter Medical School decided to make a formal study of their email correspondents and among the questions, the scientists asked their subjects to picture things like a sunrise. Try as they might, most of the respondents couldn’t see anything. But some of them did report rare, involuntary flashes of imagery. The mention of a friend’s name, for instance, might briefly summon a face.
When the scientists asked their subjects to mentally count the windows in their house or apartment, 14 succeeded. They seem to share MX’s ability to use alternate strategies to get around the lack of a mind’s eye.
In their new report, the scientists note that many of the survey respondents differed from MX in an important way. While he originally had a mind’s eye, they never did. If aphantasia is real, it is possible that injury causes some cases while others begin at birth.
Thomas Ebeyer, a 25-year-old Canadian student, discovered his condition four years ago while talking with a girlfriend. He was shocked that she could remember what a friend had been wearing a year before.
She replied that she could see a picture of it in her mind.
“I had no idea what she was talking about,” he said in an interview. Mr. Ebeyer was surprised to discover that everyone he knew could summon images to their minds. Last year, someone showed him my article about MX.
Dr. Zeman now wonders just how common aphantasia is. “Moderately rare” is his guess, but to follow up, he has sent the questionnaire to thousands of people in Exeter.
He hopes to find enough people with the condition to begin a bigger scanning study, comparing their brains with those of people who see vivid mental images.
A version of this article appears in print on June 23, 2015, on page D3 of the New York edition with the headline: Picture This? Some Just Can’t.
Source: The New York Times