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June 14, 2021

Why some people have no 'mind's eye'

Daily Briefing
    Editor's note: This popular story from the Daily Briefing's archives was republished on Dec. 8, 2021.

    After a patient lost his ability to conjure images in his mind, a phenomenon commonly referred to as having a "mind's eye," following heart surgery, one of his providers began exploring the condition—including whether it could be treated, or whether it even qualifies as a condition meriting treatment, Carl Zimmer reports for the New York Times.

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    Losing your mind's eye

    Adam Zeman, a cognitive scientist at the University of Exeter in Britain, first learned about the condition called aphantasia through a patient who said that following a minor heart surgery, he was unable to conjure images of the people or objects he was thinking about. However, the patient's visual memories were still intact. He was able to answer questions about what former British Prime Minister Tony Blair looked like, and he could solve problems requiring mentally rotating shapes, despite being unable to see them in his mind.

    Zeman wrote a case study about the patient, and then began to explore the condition more widely. Based on research by Zeman and colleagues, experts estimate that around 0.7% of people have aphantasia, while around 2.6% of people have the opposite—an extraordinarily strong mind's eye, referred to as hyperphantasia.

    But in his subsequent research, Zeman realized that his initial aphantasia patient was unique. Most people who have the condition have no memory of ever having a mind's eye, suggesting they never had one to begin with, Zimmer reports.

    However, much like Zeman's patient, most people without a mind's eye had no problems remembering the things and people they had seen. And while they did not do as well as others did at recollecting the details of their lives, there could be some advantages to the condition: They may be less likely that those with hyperphantasia to generate false memories, and they could evade some of the burdens caused by reliving traumatic moments, since they cannot visualize them.

    Why aphantasia and hyperphantasia happen

    Over the years, Zeman and Joel Pearson, a cognitive neuroscientist at the University of New South Wales, have conducted multiple studies looking into the brain activity in people with aphantasia and hyperphantasia.

    In one study, Pearson and colleagues examined aphantasia and the correlations with a person’s pupils shrinking. Specifically, they asked participants to imagine a white triangle and found that while most people's pupils constricted when they did, the pupils of most people with aphantasia did not—their pupils remained open, regardless of how hard they attempted to imagine the triangle.

    In a different study, Pearson monitored participants' skin while they read scary stories that were projected on a screen. When most people read these frightening stories, they experienced a jump in skin conductance. But those with aphantasia didn't.

    According to Zimmer, these studies suggest the mind's eye amplifies both the positive and negative feelings people feel. Those with aphantasia still have those feelings, but they're not amplified.

    Researchers have also looked at how brain circuitry works in those with aphantasia or hyperphantasia. So far, the research suggests that the areas in the front of the brain associated with decision-making send signals to parts of the brain in the back, which typically translates information from the eyes. Those "top-down signals" enable people's visual brain areas to manufacture images that aren't there, Zimmer reports.

    For instance, in a study published in May, Zeman scanned the brains of 24 people with aphantasia, 25 with hyperphantasia, and 20 with neither condition. He found that, when the participants were allowed to let their minds wander, those with hyperphantasia had stronger activity in the parts of the brain linking the front and back. These findings suggest that those with hyperphantasia can send more robust signals to the visual parts of the brain than others.

    A potential treatment for aphantasia

    Though Zeman does not consider aphantasia a "disorder" so much as one of many "intriguing variation[s] in human experience," researchers have suggested there may be ways to introduce the mind's eye to people who have not experienced it.

    For example, Pearson found that administering noninvasive magnetic pulses to the visual centers in the brains of people without either condition makes their mind's eye more vivid. He believes the pulses reduce activity in the visual centers of the brain, making it easier for the brain to receive requests from the front. As a result, Pearson said it may be possible to use the magnetic pulses, alongside cognitive training, to give someone with aphantasia a mind's eye.

    However, Pearson said he's not sure it would be a good idea to perform that kind of a procedure. If someone regretted having an increase in their mental imagery, there might not be a way to reverse the effects. "There's a dark side to that," he said.

    For his part, Thomas Ebeyer, the founder of the website Aphantasia Network, who has the condition himself, said he'd consider that kind of a treatment only if the mind's eye lasted for a few days. "If it was an experience where you take this pill and you can visualize forever, I probably wouldn't risk it," he said (Zimmer, New York Times, 6/8).

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