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To Patch a Visual Gap, Turn That Text Around


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Fixation maps

Image Credit: Experimental Brain Research (Springer)

Reader, be proud. You’re a perceptual expert.

As you read, your eyes alternately focus and move along each line of text in a seamless sequence honed over years of practice. Reading, recognizing faces and distinguishing colors or musical tones are all forms of perceptual expertise.

To appreciate the visual skill involved in reading, turn a text upside down. You’ll stumble along in fits and starts, your eyes pausing longer and more often, each movement bringing less information to your brain.

To assess how such neuro-ocular blundering might be improved, researchers at the University of British Columbia asked seven volunteers to practice reading novels upside down. After 30 half-hour sessions over a period of 10 weeks, they gained an average of 35 words per minute in reading speed on inverted text.

This could be promising news for people with right hemianopia (hemi-uh-NOH-pee-uh), a condition that erases part of the right field of vision in both eyes. Any damage to the left occipital lobe of the brain, or the pathways connecting it to the eyes, can cause this disorder. Hemianopia, from the Greek for “half sight,” most often results from a stroke, but can also befall patients with multiple sclerosis, brain tumors or traumatic injuries.

When we read, we see only three or four letters to the left of our eyes’ fixation point, but we pick up information 10 to 15 letters to the right. So in a society that reads from left to right, left hemianopia has little effect on reading ability, but right hemianopia can be devastating. Brain injury patients rank the inability to read among the most significant effects on their quality of life.

Since inverted text is read from right to left, those who have lost vision to the right can gain more information with each fixation. Other therapeutic approaches involve practicing longer rightward eye movements, but reading upside down is more of a strategic approach, says neuro-ophthalmologist Jason Barton, senior author of the study. “I can’t change the fact that you’ve got this blind area,” Barton says, “but how can I help you live with it? How can I help you circumvent it?”

Barton and his team set out to test whether healthy people could learn to read inverted text as efficiently as upright text, and how long it might take. Before and after training, they measured subjects’ reading speed in both orientations when reading silently or aloud.

Subjects practiced at home by reading novels online upside down. The novels, rated at an eighth-grade level or lower, included Alice in Wonderland and The Count of Monte Cristo. Every five pages, participants answered multiple-choice questions about the text to reinforce comprehension. They gained an average of 1.2 words per minute each session, for a total improvement of 35 words per minute.

To reveal which changes in ocular movement contributed to this progress, the researchers used a video eye-tracker to record the position of the left eye 1,000 times per second while subjects read aloud, both before and after the 10 weeks of training. In the example shown here, each circle represents a single fixation of the eye on the text, its diameter proportional to the duration of fixation. The contrast between the inverted text before and after training shows that the number and length of fixations decreased, making reading more efficient.

The subjects also made fewer eye movements, with a lower proportion of backwards movements, suggesting they picked up information from text more economically after training. Overall, the 10 weeks of practice closed about 30 percent of the gap in reading ability between upright and inverted text. The team reported their findings on Dec. 27 in Experimental Brain Research.

Barton is encouraged by the outcomes of the training, but cautions that three or four times more training may not lead to 100 percent progress. “Given all the years of practice you have with upright, it’s probably unrealistic for us to promise you after 40 weeks of reading three times a week upside down that you’ll be just as good,” he says. “I suspect it will take more practice.”

Even if people with hemianopia can become proficient at reading upside down, they may be too embarrassed to do so in public. “You have to deal with stares of people looking at you as you’re reading upside down,” Barton says. Neurologist Alex Leff at University College London voices similar concerns; he says his patients are not interested in reading upside down. In addition to the stares, he points out, “A lot of the text we read in the environment cannot be manipulated in this way.”

Leff advocates practice with reading laterally scrolling text, which can increase the ability to make rightward eye movements. Barton believes that, in addition to training with inverted text, patients can learn to enlarge their perceptual span to the left, from just three or four letters to six or seven. He’s beginning to test the potential of this method to increase reading speed.

“After all, perceptual span is not something that’s hard-wired,” Barton says. “You develop that through the course of living in a language that reads from left to right. These things are malleable.” The study is the first to demonstrate this malleability in adult readers. Previous analyses of children’s ability to read upside down confounded perceptual expertise with language acquisition.

Oddly, texts written in stone are a testament to the flexibility of reading direction. Many ancient Greek inscriptions use a method of writing called boustrophedon, or “ox-turning,” in which every other line of text is inverted. The writer’s hand—and the reader’s eye—mimics the back-and-forth trajectory of an ox plowing a field. So ancient wisdom could show the plasticity of our modern perceptual abilities.

Molly Sharlach About the Author: Molly Sharlach cut her science chops studying bacterial spot disease of tomato at the University of California, Berkeley. Now she writes about innovative therapies, threatened ecosystems and insect architects as a graduate student in science communication at UC Santa Cruz. See more of her work at www.mollysharlach.net. Follow on Twitter @MollySharlach.

The views expressed are those of the author and are not necessarily those of Scientific American.






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