Think about your breakfast this morning. Can you imagine the pattern on your coffee mug? The sheen of the jam on your half-eaten toast?
Most of us can call up such pictures in our minds. We can visualize the past and summon images of the future. But for an estimated 4% of people, this mental imagery is weak or absent. When researchers ask them to imagine something familiar, they might have a concept of what it is, and words and associations might come to mind, but they describe their mind’s eye as dark or even blank.
The human imagination: the cognitive neuroscience of visual mental imagery
Systems neuroscientist Mac Shine at the University of Sydney, Australia, first realized that his mental experience differed in this way in 2013. He and his colleagues were trying to understand how certain types of hallucination come about1, and were discussing the vividness of mental imagery.
“When I close my eyes, there’s absolutely nothing there,” Shine recalls telling his colleagues. They immediately asked him what he was talking about. “Whoa. What’s going on?” Shine thought. Neither he nor his colleagues had realized how much variation there is in the experiences people have when they close their eyes.
This moment of revelation is common to many people who don’t form mental images. They report that they might never have thought about this aspect of their inner life if not for a chance conversation, a high-school psychology class or an article they stumbled across (see ‘How do you imagine?’).
Although scientists have known for more than a century that mental imagery varies between people, the topic received a surge of attention when, a decade ago, an influential paper coined the term aphantasia to describe the experience of people with no mental imagery2.
Since then, aphantasia has shot into the canon of unusual phenomena that are invaluable for studying how the mind works. Like synaesthesia (in which people’s senses are connected in exceptional ways, so they hear colours, for example) and prosopagnosia (also known as face blindness), aphantasia has opened many new research avenues.
Much of the early work sought to describe the trait and assess how it affected behaviour. But over the past five years, studies have begun to explore what’s different about the brains of people with this form of inner life3. The findings have led to a flurry of discussions about how mental imagery forms, what it is good for and what it might reveal about the puzzle of consciousness: researchers tend to define mental imagery as a conscious experience, and some are now excited to study aphantasia as a way to probe imagery’s potentially unconscious forms.
Cognitive neuroscientist Giulia Cabbai at University College London is among the researchers interested in these questions. She was shocked to learn about aphantasia in 2015. Her own intensely vivid mental imagery is at the other extreme of the distribution — she has hyperphantasia. The fact that there are people with a complete lack of mental imagery brings fresh ways to study this internal experience, she says. “How does it affect our emotion, our perception, our attention, our memory? We can understand this with aphantasia.”
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