Many of the etchings by artist M. C. Escher appeal because they depict scenes that defy logic. His famous “Waterfall” shows a waterwheel powered by a cascade pouring down from a brick flume. Water turns the wheel and is redirected uphill back to the mouth of the flume, where it can once again pour over the wheel in an endless cycle. The drawing shows us an impossible situation that violates nearly every law of physics.
In 2003 a team of psychologists led by Catya von Károlyi of the University of Wisconsin–Eau Claire made a discovery using such images. When the researchers asked people to pick out impossible figures from similarly drawn illustrations, they found that participants with dyslexia were among the fastest at this task.
Dyslexia is often called a learning disability. And it can indeed present learning challenges. Although its effects vary widely, some children with dyslexia read so slowly that it would typically take them months to read the same number of words that their peers read in a day. Therefore, the fact that people with this difficulty were so adept at rapidly picking out the impossible figures puzzled von Károlyi.
The researchers had stumbled on a potential upside to dyslexia, one that investigators have just begun to understand. Scientists had long suspected dyslexia might be linked to creativity, but laboratory evidence for this was rare. In the years to follow, sociologist Julie Logan of Cass Business School in London showed that there is a higher incidence of dyslexia among entrepreneurs than in the general population. Meanwhile cognitive scientist Gadi Geiger of the Massachusetts Institute of Technology found that people with dyslexia could attend to multiple auditory inputs at once.
These findings raise the intriguing possibility that dyslexia involves certain advantages. The research hints that people with dyslexia exhibit strengths for seeing the big picture (both literally and figuratively) that others tend to miss. And if this is true, the work reinforces the larger idea that differences that people might perceive as a source of difficulty in some domains can become a source of strength in other contexts.
Weeds among the Flowers
In our lab at the Harvard-Smithsonian Center for Astrophysics, we have studied various scientific talents among people with dyslexia. Biochemist Christopher Tonkin of the biotechnical company Biogen Idec, for example, has long noticed a sensitivity to “things out of place,” which he ascribes to his dyslexia. Tonkin is easily bothered by the weeds among the flowers in his garden, and his awareness of visual anomalies has aided his research.
Our studies hint that dyslexia may be an asset to many scientists. For example, in 2012 we asked 15 college students to search for specific objects in busy photographs of natural scenes. Some of these scenes appeared repeatedly, which allowed us to measure how well students could learn the layout of such images. Dyslexic individuals needed fewer repetitions to master these searches than their nondyslexic peers, but only for blurred images. Such skills could translate well in medicine, for example, where physicians compare multiple diagnostic x-rays over time to identify tumors or growths.
Further evidence comes from studies by neuroscientist Martina Hedenius of Uppsala University in Sweden. In 2014 her team reported that among 28 children, those with dyslexia were more accurate in recognizing whether they had previously seen a given image.
Although we do not know precisely what would cause these advantages, we do have an understanding of how literacy changes the brain. An avid reader might read for an hour or more daily, for years on end. This specialized repetitive training, requiring split-second control over eye movements and perception, can shape the visual system to make some pathways more efficient than others.
Collège de France cognitive neuroscientist Stanislas Dehaene and his colleagues have identified some of these changes. In a study published in 2014 they asked 63 adults with varying degrees of literacy to rapidly identify whether pairs of letters and pictures oriented in various ways were the same or different. Curiously, when the pairings depicted mirror reversals of one another, people with greater literacy struggled to recognize the similarity more than their less literate counterparts.
Dehaene has concluded that the ability to carry out certain types of visual processing may be lost as reading is acquired. Visual strengths in dyslexia might thus be an artifact of differences in the brain created by reading.
My colleagues and I have offered an alternative explanation. One reason people with dyslexia may exhibit visual talents could be that they have difficulty managing visual attention, the ability to rapidly orient to changes in the environment. Visual attention is critical in perceiving letters within words and in guiding eye movement during reading.
Strong readers are necessarily skilled at focusing visual attention. But a trade-off is involved: when focusing on detail, the brain suppresses awareness of its surroundings. Poor readers may be unable to focus attention in this way. They would therefore be more globally aware, which could lead to advantages for performing tasks, such as discriminating impossible figures.
This theory is encouraged by ongoing studies by Italian psychologist Andrea Facoetti of the University of Padua. In 2012 Facoetti's team asked 82 children in preschool to do a variety of tasks, such as a visual search, characterizing their individual strengths for visual attention. The children were then taught to read in first and second grades. When their reading proficiency was evaluated at the end of this period, Facoetti found that those who showed difficulties with visual attention in preschool tended to also express difficulties with reading in second grade. These findings raise the possibility that visual attention deficits, present from a very early age, are at least in part responsible for the challenges characteristic of dyslexia.
Facoetti's work also suggests that the observed advantages are not an incidental by-product of limited reading experience. Instead both the benefits and challenges of dyslexia might emerge from differences in the brain that were most likely present from birth. Further evidence of this paradox comes from longitudinal neuroimaging research by neurologists at the University of Southern California. Children in preschool, who later developed dyslexia, were found to have thinner gray matter in parts of the cortex linked to audition, vision and attention than their nondyslexic peers did. More important, these differences were evident before reading was taught.
Given the fact that attention affects perception in many ways, lifelong differences in this area might spur any number of abilities. These might include the ability to notice subtle undulations in complex mathematical graphs or to remember the spatial layout in a graphical organizer, such as the periodic table of elements.
Whether observations of such advantages in the lab apply to real-life talents remains an open question. But the evidence makes it clear we need to broaden our views on dyslexia to include not only the struggles but also the benefits that come from different kinds of thinking. After all, our conceptions of “advantage” and “disadvantage” have meaning only in the context of the task that needs to be performed.
In physics we know that heat engines, such as those in automobiles or power systems, can only transform energy into mechanical work by making use of differences in temperature, hot versus cold. Nothing productive takes place when everything is the same. Neurological differences similarly drive the engine of society and create the contrasts between hot and cold that generate new ideas. Impairments in one area can lead to advantages in others, and it is these differences that drive progress.