Decoding Silence

Sometimes the meaning is in what you don’t say rather than in what you do say. For example, unlike English, many East Asian languages, as well as European languages including Spanish and Italian, don’t always use pronouns, such as I, he, she, it, him, or her. In English the answer to the question, “Did John see Mary?” is “He saw Mary.” But in Chinese the answer can simply be “Saw Mary.”

A team led by University of Georgia researchers has been using functional Magnetic Resonance Imaging (fMRI) to identify the parts of the brain involved in understanding sentences that omit pronouns in this way. They found that, during language processing in these “silent" cases, Chinese speakers use a wider variety of brain regions. Chinese speakers employ the usual brain network for language, but they also make greater use of memory-related regions.

Although dropped pronouns in Chinese and other languages have been extensively studied, the UGA team is the first to examine the brain regions involved using neuroimaging via fMRI while the research participants listened to an audiobook.

“We used a Chinese language audiobook of Saint-Exupery’s The Little Prince instead of specifically constructed sentences because we wanted to study the natural process of language understanding,” said John Hale, Arch Professor of World Languages in the Franklin College of Arts and Sciences department of linguistics and leader of the project.

Shulin Zhang is a doctoral student in the department of linguistics and first author of the team’s research study describing their results published in the journal Brain and Language.

She explains how this study uses a technique called “searchlight" to locate regions of the brain that distinguish different story characters. Searchlight decodes the pattern of activation in particular brain areas.

Zhang adds that neuroimaging showed left temporal regions at work during language comprehension, as well as areas called the parahippocampal gyrus and the precuneus.

“The left temporal region is highly relevant to language processing and considered a core area of the language network," Zhang notes. “The other regions, the parahippocampal gyrus and the precuneus, are relevant to things like short term memory and discourse processing. These regions can be considered extended nodes of the language network.”

“Decoding the gaps or the dropped pronouns requires more effort in that your brain must use additional non-core areas of the language network. Previously, it was thought that the brain only used a variety of context clues. Recruitment of the extended language network tells us that memory is also involved,” Zhang said.

Image: Mandarin character for personal pronoun "ni”, meaning “you”.