American Scientist Magazine

ORE Open Research Exeter TITLE Blind Mind's Eye AUTHORS Zeman, A JOURNAL American Scientist Magazine DEPOSITED IN ORE 08 June 2021 This version available at http://hdl.handle.net/10871/125978 COPYRIGHT AND REUSE Open Research Exeter makes this work available in accordance with publisher policies. A NOTE ON VERSIONS The version presented here may diﬀer from the published version. If citing, you are advised to consult the published version for pagination, volume/issue and date of publication A reprint from American Scientist the magazine of Sigma Xi, The Scientific Research Honor Society This reprint is provided for personal and noncommercial use. For any other use, please send a request to Permissions, American Scientist, P.O. Box 13975, Research Triangle Park, NC, 27709, U.S.A., or by electronic mail to [email protected]. ©Sigma Xi, The Scientific Research Hornor Society and other rightsholders Blind Mind’s Eye People with aphantasia cannot visualize imagery, a trait that highlights the complexities of imagination and mental representation. Adam Zeman hich is darker: the green “hear” the sound of distant thunder, a map that we have memorized, we of grass or the green of a “feel” the touch of velvet, or imagine answer more swiftly if they lie close to- pine tree? Does a squir- running for a bus by engaging audi- gether rather than far apart, as if we rel have a short or a long tory, tactile, and motor imagery, respec- were scanning the map with our eyes Wtail? Is a walnut larger than a hazelnut? tively. Olfactory imagery is more elu- before we respond; in deciding whether Do Labradors have rounded ears? To sive, but many of us can relish the scent one object is a rotated version of the oth- answer questions such as these, you of a rose or shrink from the smell of er, the timing of the decision depends probably summoned up images of the sewage. To some degree, we can evoke on the extent of the rotation. A beau- mentioned items to inspect them in absent emotions, imagining a breath tifully simple observation epitomizes your “mind’s eye.” When you enjoy of sadness or a sudden jolt of surprise. work along these lines: If visualizing is a novel, you likely come away with Although this article focuses on visual really like seeing, visualizing something a visual impression of the characters imagery, the broad principles seem to bright should cause a constriction of the and scenes described—which can apply to imagery of all types. pupil, as would occur when looking lead to that familiar disappointment Experiences of imagery are ubiqui- at something bright. Bruno Laeng at if the book is turned into a movie: “He tous. They contribute to our recollection the University of Oslo has shown that, looked nothing like I’d imagined him!” of the past (think of your last holiday) indeed, if we switch our mental image Most of us can conjure images to and our anticipation of the future (how from a bright sky to a night sky or a order: Visualize the Sun rising above will you spend next weekend?). They cloudy one, the pupil duly dilates (see the horizon into a misty sky—or your figure in our daydreams and our night figure at the top of page 112). kitchen table as you left it this morn- dreams. They have been implicated in But there is more to imagery than it ing. But it turns out that 1 to 3 per- creative work in both the sciences and being simply “weak perception.” Let’s cent of the population entirely lack the the arts. Albert Einstein wrote: “I very say that I ask you to imagine a tulip, ability to visualize—a condition called rarely think in words at all,” relying and you succeed—what color was it, by aphantasia—whereas others have hyper- instead on “more or less clear images the way?—you engage a whole team of phantasia and experience imagery as which can be voluntarily ‘reproduced’ more basic cognitive abilities: You must vivid as actual sight. These imagery and combined. .” The novelist Joseph be awake and attentive, you require vividness extremes are prime examples Conrad emphasized the importance of your command of the English language of invisible differences that are easily imagery to his craft: “My task . is, by to decode the instruction, you need overlooked but are salient features of the power of the written word to make your memory to retrieve your knowl- the inner lives of those concerned. Un- you hear, to make you feel—it is, before edge of tulips and their appearance, derstanding how such differences arise all, to make you see.” you need to use your executive function can help us learn about the many ways Research over the past century has to orchestrate the whole process, and the mind can implement imagination taught us much about the psychology you use your perceptual system to gen- and mental representation. of imagery generally and its basis in the erate the sense of “looking at” a tulip. brain. An impressive series of experi- This description reminds us that, like The Science of Imagery ments by Stanford University psycholo- any cognitive act, forming an image is Imagery involves the sensory experi- gist Roger Shepard, Harvard University a process rather than an instantaneous ence of items in their absence: When neuroscientist Stephen Kosslyn, and event. A measurable amount of time we visualize a pine tree or the rising others showed that imagery is indeed, passes between receiving the instruc- Sun, most of us have an experience that as intuition might suggest, an echo of tion to “visualize a tulip” and becom- is a bit like seeing. But we can form im- perception. If we are asked to shift our ing able to inspect and manipulate its agery in other sense modalities too: We mental gaze between two objects on image in the mind’s eye. On the basis QUICK TAKE A condition called aphantasia affects 1 to A survey about imagery vividness from Aphantasia does not imply a lack of imagi- 3 percent of the population. Aphantasics lack 1880 was the first to document the condition, nation, which indicates that the brain has a the ability to visualize imagery—a term that but it remained a little-studied phenomenon wide range of methods for cognitive represen- includes all the senses, not just sight. until the past few decades. tation, some more abstract than experiential. 110 American Scientist, Volume 109 © 2021 Sigma Xi, The Scientific Research Honor Society. Reproduction with permission only. Contact [email protected]. It is now almost half a century since one other fascinating line of evidence began to illuminate the science of imagery. Functional brain imaging relies on the simple principle that the brain is like muscle: When it becomes active in a task, the blood flow to activated regions ramps up. We can observe this change in several ways, most com- monly using magnetic resonance imaging that is sensitive to local changes in oxygen concentrations. Two years ago my colleague Crawford Winlove identified 40 studies that had examined brain activation during imagery tasks. The regions he and others have identified (see figure at the bottom of page 112) are in keeping with the cognitive processes required to call a tulip to the mind’s eye—areas in the frontal and parietal lobes linked to cognitive control, atten- tion, and eye movements; areas linked to language processing; areas involved with memory; and visual cortices in the occipital and temporal lobes. The leading edge of such research is now focused on “mind reading,” which is the effort to decode the contents of the mind’s eye using brain-imaging data. Studies examining the time course of acts of visualization in the brain high- light another, intuitively obvious, dif- ference between imagery and perception. When we see, information streams in from the eyes to the brain, driving activity that spreads through the visual system and deep into the brain, allow- ing us, among other things, to recog- nize what we see. Visualization is “vi- sion in reverse”: The brain begins with a decision or instruction—”imagine a tulip”—and uses its stored knowledge of appearances to drive activity within the visual system that leads to the experience of imagery. Imagery, in brief, allows us to simu- Artefact/Alamy Stock Photo late sensory experience “offline,” en- Wonderland by Adelaide Claxton (1841–1927) depicts the mental imagery (here, a smoky imag- abling at least a partial reenactment of inary figure) that our brains regularly conjure up while reading or while doing any other task our past encounters with the world. where we are asked to visualize. People with aphantasia cannot create these mental images. The usual explanation for why we have imagery is that it ultimately enhances of a series of behavioral experiments images tend to fade rapidly, probably our ability to predict the future and act like those described above that he and because the visual brain is designed effectively within it. This purpose may his team undertook in the 1980s, Koss- to deal with rapidly changing scenes. be true, but recent findings somewhat lyn described four key processing steps Keeping an image in mind requires complicate this story. in our engagement with images. First, maintenance, Kosslyn’s second process- images must be generated: This step in- ing step. If we want to use an image to Rediscovering Aphantasia volves mobilizing information about answer a specific question—does your Sir Francis Galton was a Victorian sci- how things look and using it to create tulip have a long stem?—we need to entist with a passion for measurement, a representation of the visualized item inspect it, which is the third step; if we which was misapplied in his role in in what he called the “visual buffer,” want to manipulate the image, such as the development of eugenics.

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