‘An intriguing variation in human experience’
Scientists explore why many have vivid ‘mind’s eye,’ others have none
Dr. Adam Zeman didn’t give much thought to the mind’s eye until he met someone who didn’t have one. In 2005, the British neurologist saw a patient who said that a minor surgical procedure had taken away his ability to conjure images.
Over the 16 years since that first patient, Zeman and his colleagues have heard from more than 12,000 people who say they don’t have any such mental camera. The scientists estimate that tens of millions of people share the condition, which they’ve named aphantasia, and millions more experience extraordinarily strong mental imagery, called hyperphantasia.
In their latest research, Zeman and his colleagues are gathering clues about how these two conditions arise through changes in the wiring of the brain that join the visual centers to other regions. And they’re beginning to explore how some of that circuitry may conjure other senses, such as sound, in the mind. Eventually, that research might even make it possible to strengthen the mind’s eye — or ear — with magnetic pulses.
“This is not a disorder as far as I can see,” said Zeman, a cognitive scientist at the University of Exeter in Britain. “It’s an intriguing variation in human experience.”
The patient who first made Zeman aware of aphantasia was a retired building surveyor who lost his mind’s eye after minor heart surgery. To protect the patient’s privacy, Zeman refers to him as M.X.
When M.X. thought of people or objects, he did not see them. And yet his visual memories were intact. M.X. could answer factual questions such as whether former Prime Minister Tony Blair has light-colored eyes.
(He does.) M.X. could even solve problems that required mentally rotating shapes, even though he could not see them.
To better understand aphantasia, Zeman and his colleagues invited their correspondents to fill out questionnaires. One described the condition as feeling the shape of an apple in the dark. Another said it was “thinking only in radio.”
The vast majority of people who reported a lack of a mind’s eye had no memory of ever having had one, suggesting that they had been born without it. Yet, like M.X., they had little trouble recalling things they had seen. When asked whether grass or pine tree leaves are a darker shade of green, for example, they correctly answered the leaves.
On the other hand, people with aphantasia don’t do as well as others at remembering details of their own lives. It’s possible that recalling our own experiences — known as episodic memory — depends more on the mind’s eye than does remembering facts about the world.
To their surprise, Zeman and his colleagues were also contacted by people who seemed to be the opposite of M.X.: They had intensely strong visions, a condition the scientists named hyperphantasia.
Joel Pearson, a cognitive neuroscientist at the University of New South Wales who has studied mental imagery since 2005, said hyperphantasia could go far beyond just having an active imagination. “It’s like having a very vivid dream and not being sure if it was real or not,” he said. “People watch a movie, and then they can watch it again in their mind, and it’s indistinguishable.”
Based on their surveys, Zeman and his colleagues estimate that 2.6% of people have hyperphantasia and that 0.7% have aphantasia.
Now Zeman and Pearson are studying an even larger swath of people who experience extremes of mental imagery. One of the original people with aphantasia who were studied by Zeman, Thomas Ebeyer, of Kitchener, Ontario, created a website called the Aphantasia Network that has grown into a hub for people with the condition and for researchers studying them. Visitors to the site can take an online psychological survey, read about the condition and join discussion forums on topics ranging from dreams to relationships. So far, more than 150,000 people have taken the surveys, and over 20,000 had scores suggesting aphantasia.
“This really is a global human phenomenon,” Ebeyer said. “I’ve heard from people from Madagascar to South Korea to California.”
In a study published in May, Zeman and his colleagues scanned the brains of 24 people with aphantasia, 25 people with hyperphantasia and 20 people with neither condition.
The scientists had the volunteers lie in the scanner and let their minds wander. The people with
hyperphantasia had stronger activity in regions linking the front and back of the brain. They may be able to send more potent signals from decision-making regions of the front of the brain to the visual centers at the back.
For those used to seeing things with their mind’s eye, aphantasia might seem like a debilitating condition. But Zeman’s research doesn’t suggest that to be the case. In fact, aphantasia may even have some advantages over hyperphantasia.
Hyperphantasia creates images that seem so real that it may open the way to false memories. Similarly, people with no mind’s eye
may escape some of the burdens caused by reliving traumatic experiences, because they don’t have to visually replay them.
“Anecdotally, they’re really good at moving on,” Zeman said. “One wonders whether that’s because they’re less troubled by the kinds of images which, for many of us, come to mind and give rise to regret and longing.”
Pearson said that someday it might become possible to give people with aphantasia a mind’s eye they never had. He has found that giving noninvasive magnetic pulses to visual centers in average people’s brains makes
their mental imagery more vivid. He suspects that the pulses quiet the activity of the visual centers, making them more receptive to requests from the front of the brain.
In theory, magnetic pulses combined with cognitive training might enable people without a mind’s eye to strengthen the circuits required for mental pictures. But Pearson isn’t sure it would be right to carry out such a procedure. If a person regretted such a boost in intrusive imagery, the scientist might not be able to shut the mind’s eye back down. “There’s a dark side to that,” he said.