This article provided the results of two studies supporting the hypothesis that areas of the visual system designed to recognize objects that have been repurposed over evolution to allow humans to read.

A study in 2012 conducted by French cognitive psychologists reported that baboons could learn to distinguish words from nonwords. This begged the question: were such abilities in humans the result of “recycling” existing brain areas, or of newly formed areas?

A recent study led by James DiCarlo at MIT supports the hypothesis that the ability to read developed through repurposing of existing brain areas. His group used functional magnetic resonance imaging to identify a region of the visual cortex that lights up when a word is processed by the brain. The region, called the visual word form area (VWFA), is located in the inferotemporal (IT) cortex and distinguishes words from nonsensically jumbled letters or unknown alphabets. It is a part of the orthographic process which allows humans to recognize letters and words. 

The 2012 study was an inspiration for the recent study, where the hypothesis was that patterns reflecting a predisposition to processing text in primate brains should be visible in the neural activity of primates as they looked at words. The researchers used macaques and had them look at 2,000 strings of words while about 500 neural sites were recorded. Some of the strings were English words and others were nonsensical letters. A computer model called a linear classifier then used the data to “mimic” the animal behaviour. The results of the model were similar to the ones reported in the 2012 study, with approximately 70% accuracy in distinguishing words from non-words. The errors that the model made were also similar to the ones that the animals made.

As a comparison, the researchers also tested another part of the visual cortex, V4. Here the linear classifier was not able to accurately predict or mimic the baboon’s performance as well as the IT linear classifier, suggesting that mechanisms for object recognition in the IT cortex were the basis for those involved in reading.

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This post was written by Hibah Sehar