BY THE OPTIMIST DAILY EDITORIAL TEAM
Learning to read does something to the brain beyond teaching it to decode text. A new study in Cortex found that adults with formal reading education recruit a distinct region on the right side of the brain when processing unfamiliar spoken sounds. Adults who never learned to read show no activity there at all.
The study was led by cognitive neuroscientist Mariana P. Nucci at the University of São Paulo.
The experiment
Three groups: 23 highly educated young adults, 21 highly educated older adults, and 15 older adults classified as functionally illiterate. Functionally illiterate means they might recognize common signs or letters but couldn’t read a sustained text for comprehension.
All went into an fMRI scanner and completed two listening tasks. First, they listened for a target word in a Portuguese story, their native language. They could follow the narrative and use context. Then they did the same in Japanese, which none of them spoke. No narrative thread, no meaning, no way to anticipate anything. Just an unbroken stream of unfamiliar sounds with one specific sequence to catch.
In Portuguese, the groups looked similar. The functionally illiterate adults found the target about 90 percent of the time.
Japanese separated them fast. The functionally illiterate group caught the target just 17 percent of the time. Highly educated older adults: 48 percent. Highly educated young adults: 75 percent.
Where the difference shows up
During the Japanese task, the educated older adults activated the right inferior frontal gyrus, a region near the temple on the right side of the brain. It’s the counterpart to Broca’s area, which sits on the left and handles speech production and language comprehension.
The functionally illiterate adults showed no activity there. And performance on the task tracked closely with reading proficiency scores across all participants. The connection isn’t subtle.
The researchers’ interpretation: this region applies explicit phonological analysis to sound, the kind of deliberate, conscious sound-processing that reading instruction specifically trains. Speaking a language, it turns out, doesn’t build the same thing.
What reading teaches the ear to do
Phonological awareness is the ability to break words into their component sounds and work with them deliberately. It’s what you’re using when you catch a rhyme, count syllables, or sound out an unfamiliar word. Reading instruction builds it systematically.
A clean test: ask someone to repeat a nonsense word back accurately. It requires holding a sound sequence in short-term memory with nothing semantic to anchor it. Literate adults tend to do fine. Adults without reading education tend to drop parts of the sequence.
The new study adds a specific brain region to that picture. When meaning isn’t available as a guide, literate adults have an extra resource. In this study, non-literate adults didn’t activate it.
What the study can and can’t show
The functionally illiterate group was small, 15 people, which limits how much the imaging data can carry on its own. It’s also hard to find people without formal schooling who’ll agree to spend time in a loud scanner.
The authors are careful about one confound: the functionally illiterate participants generally had fewer economic resources and more exposure to chronic stress across their lives. Both independently affect brain development. Research using nonverbal audio tasks could help separate what literacy specifically does from everything that tends to travel alongside it.
What this study can claim is a locatable, measurable difference that appears specifically when meaning is absent and that correlates with reading ability. That’s a more concrete result than a lot of work in this area has produced.
Source study: Cortex —Literacy modulates engagement of the right inferior frontal gyrus in phonological processing of spoken language
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