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People who can't picture anything are rewriting the science of imagination
Some people can't picture anything in their heads, and studying their brains is overturning a popular theory of how imagination works.
Some people have lost a large stretch of the brain tissue that first receives what the eyes send in, and yet, when they close their eyes and try, they can still call up a picture of a face or a room. Such patients sit awkwardly beside an influential idea about how imagination works, one that treats the mind’s eye as ordinary seeing run backward through the same hardware.
A new review in the journal Consciousness and Cognition, written by Derek Arnold, Loren Bouyer, Blake Saurels and Samuel Schwarzkopf, argues that this backward-seeing picture has run out of road, and that the people best placed to show why are those who can’t form mental pictures at all. Their condition is called aphantasia, from the Greek phantasia, a piece of information drawn from the senses, and it describes a lifelong inability to imagine sights, and often sounds, smells, tastes or touch as well.
The plain answer to why some people can’t visualize, according to the review, is that a set of brain regions spread from the front of the head to the sides fails to work as a team. Two of the authors are themselves unable to picture anything, and their accounts, together with the patients whose visual cortex was destroyed, support a view in which a mental image is something many parts of the brain make together and no single region owns.
When you look at a cup, the signal from your eyes lands first in a patch at the very back of the brain called the primary visual cortex. In 2019, Joel Pearson described a model in which imagining a cup runs that pipeline backward. Planning areas at the front start the request, memory regions supply the details, and the picture is painted back onto the primary visual cortex, the same screen that real seeing uses, so that how strongly this back region lights up should decide how vivid your mental image feels.
Brain scanners can often tell which image a person is imagining by reading activity in this back region, and researchers have taken that as proof that the region builds the image. Arnold and his colleagues push back, writing that such interpretations “ignore the adage that correlation does not establish causation.” Paying attention to an imagined shape could nudge the back of the brain enough for a scanner to read it, even if that activity plays no part in the felt experience of a picture.
Stronger evidence came when Rebecca Keogh, Johanna Bergmann and Pearson passed a mild electrical current through the scalp to quiet the primary visual cortex, and people then reported more vivid imagery. Arnold’s team accepts that the region can turn imagery up or down, while noting that it could do so by shaping activity in other areas that do the real work, much as a dimmer switch changes a room without producing any light of its own.
The hardest evidence comes from the clinic, where several people have kept the power to visualize despite extensive damage to primary visual cortex. One patient studied by Beatrice de Gelder and colleagues was blind across his whole field of view because both sides of that region were destroyed, yet when asked to imagine an angry person, the front and side regions of his brain responded much as they do in sighted people. If the mind’s eye needed that back screen, such a person shouldn’t be able to picture anything.
Pooling the brain-scanning studies tells the same story. Alfredo Spagna, Paolo Bartolomeo and colleagues combined dozens of imagery experiments and found that imagining reliably engaged the front of the brain and a strip along the underside of the left temporal lobe called the fusiform gyrus, a region already known for recognizing faces and written words, while the primary visual cortex was often quiet. A case reported by Sandra Thorudottir and colleagues pointed the same way, since an architect lost his ability to imagine after a stroke to this left tempora