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People with aphantasia cannot visualize imagery, a trait that highlights the complexities of imagination and mental representation.
Which is darker: the green of grass or the green of a pine tree? Does a squirrel have a short or a long tail? Is a walnut larger than a hazelnut? Do Labradors have rounded ears? To answer questions such as these, you probably summoned up images of the mentioned items to inspect them in your "mind's eye." When you enjoy a novel, you likely come away with a visual impression of the characters and scenes described-which can lead to that familiar disappointment if the book is turned into a movie: "He looked nothing like ľd imagined him!"
Most of us can conjure images to order: Visualize the Sun rising above the horizon into a misty sky-or your kitchen table as you left it this morning. But it turns out that 1 to 3 percent of the population entirely lack the ability to visualize-a condition called aphantasia-whereas others have hyperphantasia and experience imagery as vivid as actual sight. These imagery vividness extremes are prime examples of invisible differences that are easily overlooked but are salient features of the inner lives of those concerned. Understanding how such differences arise can help us learn about the many ways the mind can implement imagination and mental representation.
The Science of Imagery
Imagery involves the sensory experience of items in their absence: When we visualize a pine tree or the rising Sun, most of us have an experience that is a bit like seeing. But we can form imagery in other sense modalities too: We "hear" the sound of distant thunder, "feel" the touch of velvet, or imagine running for a bus by engaging auditory, tactile, and motor imagery, respectively. Olfactory imagery is more elusive, but many of us can relish the scent of a rose or shrink from the smell of sewage. To some degree, we can evoke absent emotions, imagining a breath of sadness or a sudden jolt of surprise. Although this article focuses on visual imagery, the broad principles seem to apply to imagery of all types.
Experiences of imagery are ubiquitous. They contribute to our recollection of the past (think of your last holiday) and our anticipation...