We do have a 'grammar' in our head

New York

"One of the foundational elements of Chomsky's work is that we have a grammar in our head, which underlies our processing of language," said senior researcher David Poeppel from the New York University.

"Our neurophysiological findings support this theory: we make sense of strings of words because our brains combine words into constituents in a hierarchical manner -- a process that reflects an 'internal grammar' mechanism," Poepple added.

The research on Chomsky's 1957 work, posited that we can recognise a phrase such as "colourless green ideas sleep furiously" as both nonsensical and grammatically correct because we have an abstract knowledge base that allows us to make such distinctions even though the statistical relations between words are non-existent.

The researchers explored how linguistic units are represented in the brain during speech comprehension.

Series of experiments were conducted using magnetoencephalography (MEG), which allows measurements of the tiny magnetic fields generated by brain activity, and electrocorticography (ECoG), a clinical technique used to measure brain activity in patients being monitored for neurosurgery.

The study's subjects listened to sentences in both English and Mandarin Chinese in which the hierarchical structure between words, phrases, and sentences was dissociated from intonational speech cues -- the rise and fall of the voice -- as well as statistical word cues.

The results showed that the subjects' brains distinctly tracked three components of the phrases they heard, reflecting a hierarchy in our neural processing of linguistic structures: words, phrases, and then sentences -- at the same time.

"Our brains lock onto every word before working to comprehend phrases and sentences. The dynamics reveal that we undergo a grammar-based construction in the processing of language," Poeppel explained.

The research appeared in the latest issue of the journal Nature Neuroscience.