`Not face` is a universal part of language: Study

Washington: Scientists have identified a single 'not face' expression that is a universal part of language, being interpreted across many cultures as the embodiment of negative emotion.

It consists of a furrowed brow, pressed lips and raised chin, and because we make it when we convey negative sentiments, such as "I do not agree," researchers are calling it the "not face."

The study also shows that our facial muscles contract to form the "not face" at the same frequency at which we speak or sign words in a sentence.

We all instinctively make the "not face" as if it were part of our spoken or signed language, researchers said.

"This study strongly suggests a link between language and facial expressions of emotion," said Aleix Martinez from Ohio State University.

Researchers sat 158 students in front of a digital camera. The students were filmed and photographed as they had a casual conversation with the person behind the camera in their native language.

The students belonged to four groups, which were chosen to represent a wide variety of grammatical structures - English, Spanish, Mandarin, and American Sign Language (ASL).

Like other forms of sign language, ASL combines hand gestures, head and body movements and facial expressions to communicate individual words or phrases.

Students either memorised and recited negative sentences that researchers had written for them ahead of time, or the students were prompted with questions that were likely to illicit disagreement, such as "a study shows that tuition should increase 30 per cent. What do you think?".

In all four groups - speakers of English, Spanish, Mandarin and ASL - the researchers identified clear grammatical markers of negation.

The students' answers translated to statements like "that is not a good idea," and"they should not do that."

Researchers manually tagged images of the students speaking, frame by frame, to show which facial muscles were moving and in which directions.

Then computer algorithms searched the thousands of resulting frames to find commonalities among them.

A "not face" emerged - the furrowed brows of "anger" combined with the raised chin of "disgust" and the pressed-together lips of "contempt".

Regardless of language - and regardless of whether they were speaking or signing - the participants' faces displayed these same three muscle movements when they communicated negative sentences.

Researchers discovered that ASL speakers sometimes make the "not face" instead of signing the word "not" - a use of facial expression in ASL that was previously undocumented.

The findings were published in the journal Cognition.