How our brain produces language and thought, according to neuroscientists

For thousands of years, philosophers have debated the purpose of language. Plato believed it was necessary for thinking. “Thought is the silent inner conversation of the soul with itself,” he wrote.

Many contemporary scholars have advanced similar views. Beginning in the 1960s, Noam Chomsky, a linguist at MIT, argued that we use language to reason and other forms of reasoning. “If there is a severe deficit in language, there will be a severe deficit in thought.” he wrote.

As an undergraduate, Evelina Fedorenko took Dr. Chomsky’s class and heard him describe his theory. “I really liked the idea,” she recalled. But she was confused by the lack of evidence. “A lot of the things he was saying were stated as if they were facts — the truth,” she said.

Dr. Fedorenko went on to become a cognitive neuroscientist at MIT, using brain scans to investigate how the brain produces language. After 15 years, her research led her to a startling conclusion: we don’t need a language to think.

“When you start evaluating it, you don’t find support for this role that language plays in thinking,” she said.

When Dr. Fedorenko began this work in 2009, studies found that the same brain areas required for language were also active when people made inferences or performed calculations.

But Dr. Fedorenko and other researchers discovered that this overlap was an mirage. Part of the problem with the early results was that the scanners were relatively primitive. Scientists made the most of the fuzzy scans by combining the results from all volunteers, creating an overall average of brain activity.

In her own research, Dr. Fedorenko used more powerful scanners and performed more tests on each volunteer. These steps allowed her and her colleagues to collect enough data from each person To create a fine-grained image of the individual brain.

Scientists then conducted studies to identify brain circuits involved in linguistic tasks, such as retrieving words from memory and following grammar rules. In a typical experiment, volunteers read ambiguous phrases, followed by real sentences. Scientists discovered certain areas of the brain that only became active when the volunteers processed actual language.

It was for every volunteer Language network – A constellation of regions that become active during linguistic tasks. “It is very stable,” Dr. Fedorenko said. “If I survey you today, in 10 or 15 years, it will be in the same place.”

The researchers then scanned the same people while they did different types of thinking, such as solving a puzzle. “Other areas of the brain are working hard when you’re doing all these forms of thinking,” she said. But the linguistic networks remained quiet. “It became clear that none of these things seemed to interact with language circuits,” she said.

In a paper published Wednesday Writing in Nature, Dr. Fedorenko and her colleagues said studies in people with brain injuries point to the same conclusion.

Strokes and other forms of brain damage can wipe out the language network, making people struggle to process words and grammar, a condition known as aphasia. But scientists discovered this People can still do algebra And Play chess Even with aphasia. In experiments, people with aphasia can look at two numbers — 123 and 321, for example — and realize that, using the same pattern, the number 456 should follow the number 654.

If language is not necessary for thought, then why language? Communications, argue Dr. Fedorenko and her colleagues. Dr. Chomsky and other researchers have rejected this idea, citing the ambiguity of words and the difficulty of expressing our intuitions out loud. “The system is not well designed in many functional aspects.” Dr. Chomsky once said.

But large studies have indicated that languages ​​have been improved to convey information clearly and efficiently.

In one studyResearchers found that frequently used words are shorter, which makes language learning easier and speeds up the flow of information. And in another studyresearchers who studied 37 languages ​​found that grammar rules place words close together so that their combined meaning is easier to understand.

The separation of thought and language could help explain why AI systems like ChatGPT are so good at some tasks and so bad at others, said Kyle Mahowald, a linguist at the University of Texas at Austin who was not involved in the new work.

Computer scientists train these programs on vast amounts of text, uncovering the rules about how words are related. Dr. Mahowald suspects that these programs are beginning to mimic the language network in the human brain, but they are incapable of logical thinking.

“It is possible to have a very fluently grammatical text, which may or may not have a coherent basic idea,” Dr. Mahowald said.

But Jay Dove, a philosopher at the University of Louisville, believes Dr. Fedorenko and her colleagues have gone too far in distancing language from thought, especially complex ideas. “When we think about democracy, we might practice having conversations about democracy,” he said. “You don’t need language to have thoughts, but it can serve as reinforcement.”