Researchers from the University of Pittsburgh have made a remarkable breakthrough in the quest to discover how the brain processes and understands written words, using this new knowledge to temporarily scramble the minds of volunteers so that they became totally unable to recognize letters. Even more impressively, by observing their subjects’ brain acitivity as they read certain words, the team were able to identify exactly which words were being processed. Essentially, they were able to read people’s minds.
For more than a century, neuroscientists have debated whether or not the brain contains a specific compartment dedicated to the recognition of written words. A vast body of research suggests that, should this literary corner of the human brain exist, it is likely to reside in a region known as the left mid-fusiform gyrus (lmFG), which has therefore become known as the visual word form area.
To test out this hypothesis, researchers recruited four epileptic patients who had had electrodes implanted into their brains, and used these to electrically stimulate the lmFG of each subject as they took part in a series of reading challenges. As the below video shows, this stimulation caused their neural libraries to shut down, making them totally incapable of recognizing individual letters or basic words.
Significantly, this did not interfere with participants’ ability to recognize faces or other objects, indicating that this effect was limited to the processing of words.
When examining the brainwaves produced in the lmFG during reading, the researchers found that two distinct signals are produced at different time points. The first of these occurs over the initial 250 milliseconds after reading a word, before being replaced by a second signal, lasting up to 500 milliseconds.
Using a machine learning system, the researchers found that the earlier signal could be used to predict the general “gist” of the word being viewed, as words with similar structures – such as those that differ by just a single letter – tended to produce equal signals. It is during the second stage of the process, however, that the brain differentiates between specific words. Therefore, when analyzing this latter signal, the study authors were able to identify the precise word being read.
Writing in the Proceedings of the National Academy of Sciences, the team report that the “lmFG meets all of the proposed criteria for a visual word form system,” thereby corroborating a long-standing hypothesis. Their findings also indicate how the brain switches between skim reading and more thorough reading, suggesting that we are able to roughly recognize a word during the early phase of processing, but have to spend a little more time studying it in order to properly identify it.
In a statement, study co-author Elizabeth Hirshorn explained how this research might one day be put to practical use – beyond simply reading people’s minds – suggesting that “having a better understanding of this neural system could be critical for diagnosing reading disorders and developing targeted therapies.”
The visual word form area is located in the left mid-fusiform gyrus. Gray, vectorized by Mysid, colored by was_a_bee via Wikimedia Commons
