Page 9

CIM36

LAB WATCH Inhibition Enhances Reading Skills BY YAROSLAV PIGENET 9 WINTER 2015 N° 36 Reading dates back to less than 10,000 years, making it a recent adaptation when compared to the millions of years it took the human brain to evolve. Cerebral imagery has shown that the recognition of letters and animals activates the same parts of the cortex. Based on this observation, neurobiologists like Stanislas Dehaene1 have hypothesized that the ability to read stems from a kind of “biological trick:” the recycling of an ancient cognitive mechanism dedicated to the rapid identification of objects in the environment. “We know that children learning to read confuse mirror-image letters, like b/d and p/q,” notes Grégoire Borst, a researcher at LaPsyDÉ.2 This is due to the fact that the letter recognition process “repurposes” the neural circuitry that our distant ancestors used to rapidly detect the presence of threatening animals. While this strategy, called mirror generalization, was useful for spotting danger, it induces errors in differentiating words like “big” and “dig.” Consonants on the loose To study the phenomenon, LaPsyDÉ researchers asked 79 students to differentiate pairs of letters and then pairs of images on a computer screen. The results3 confirmed that these experienced adult readers needed more time to identify mirror-image than non-symmetrical letters. More importantly, participants took longer to determine that two animal images were indeed identical when preceded by mirror-image letters. This increase in response time is called the negative priming effect. To distinguish symmetrical letters, the readers must inhibit the mirror generalization process. Yet when this process becomes useful again to identify images of animals, it takes more time to reactivate it. A weapon against dyslexia A theory developed by LaPsyDÉ director Olivier Houdé, who co-authored the study with Borst, postulates that our brains rely on three systems for analyzing our environment.4 “One is fast, automatic, and intuitive. The second is slow, logical, and thoughtful, while the third is used to decide, on a case-by-case basis, which of the first two should take precedence. In children, the first two systems develop in parallel, but the third and its inhibitive capacity come later.” Processes like learning to read thus rely in part on the acquisition of an essential cerebral function: the ability to resist psychological automatisms when reasoning becomes necessary. The researchers believe that children learning to read must be able to inhibit the mirror generalization process, and that some forms of dyslexia could result from a deficiency in cognitive inhibition. Should this be confirmed, new methods could be developed to help dyslexic children, including one that would trigger the process responsible for inhibiting the mechanisms inherited from neural recycling, Borst suggests. Training exercises would not necessarily involve reading and could benefit other skills, since this type of inhibition is a general cognitive capacity used in many intellectual tasks. ii Psychology. Reading requires the ability to distinguish letters. To achieve this, recent research shows that the brain must inhibit a primal cognitive mechanism. 1. Laboratoire de neuroimagerie cognitive (INSERM / CEA). 2. Laboratoire de psychologie du développement et de l’éducation de l’enfant (CNRS / Université Paris-V / Université de Caen Basse-Normandie). 3. G. Borst et al., “The cost of blocking the mirror generalization process in reading: evidence for the role of inhibitory control in discriminating letters with lateral mirror-image counterparts,” Psychonomic Bulletin & Review, 2014. doi: 10.3758/s13423-014-0663-9. 4. Olivier Houdé, Apprendre à Résister (Paris: Le Pommier, 2014). Child asked to distinguish between mirror-image letters separated by a target cross. © LAPSYDÉ gregoire.borst@parisdescartes.fr f.derrico@pacea.u-bordeaux1.fr A photo gallery is available online: www.cnrs.fr/cnrsmagazine d’Errico and Alain Queffelec to ensure the lines composing it were not marks that could have inadvertently been made while cutting skin or meat. “We used Neanderthal tools with different techniques and motions on the same type of stone, and found the engravings were produced by passing a point into the grooves over and over again. Between 200 and 300 passages were necessary to create the pattern, which demonstrates it was intentional,” explains d’Errico. “We do not know, however, what it represents. Although it looks abstract to us, this might not have been the case for them.” The next step will be to expand the experimental protocol and improve the quality of existing 3D reconstructions. This may provide additional information on how the engraving was made, and even find out whether the author was left- or right-handed. ii


CIM36
To see the actual publication please follow the link above