Facial expressions as a mode of communication predate spoken language.
Verbal language is an incredible ability. Evolved in humans over tens of thousands of years, we can barely conceive a time before it.
It is generally considered that prior to developing verbal communication, humans already utilized a suite of facial expressions to communicate emotions.
Some of these facial expressions are now embedded in spoken language.
These expressions hold their own grammatical function and act as grammatical markers.
The current research, led by Prof. Aleix Martinez, aimed to investigate whether a facial expression that denotes negative moral judgment might have been preserved as a "unique, universal grammatical marker of negation."
The 'not face'
The team decided to search for a negative grammatical marker rather than a positive one; this was because concepts like "danger" are more vital to our survival than positive facial expressions and are therefore more likely to be obvious and easier to pick out.
It has already been established that the expressions of anger, disgust and contempt can be found across all cultures. The team wanted to investigate whether these three universal negative facial expressions had been compounded over time into a single facial expression of negation: the "not face."
To test the team's hypothesis, they filmed the faces of 158 Ohio State University students while holding a conversation in their native language. The team used a cross-section of language types.
They used participants who spoke in English (a Germanic language), Spanish (a Latin-based language), Mandarin Chinese and American Sign Language (ASL, a non-verbal method of communication).
The universality of facial expressions
The team focused on sentences that included "not," as in "I am not going to the party." The team reasoned that when an individual used the word "not" they would pull a specific type of facial expression to denote the meaning.
The students were asked to memorize and recite negative sentences written by the researchers, or they were prompted with questions that the students were likely to disagree with, for instance: "A study shows that tuition fees should increase by 30%. What do you think?"
The resulting videos of the students were analyzed frame by frame to measure the movements of the underlying facial muscles at the point in the sentence when the negation occurred.
The team found that, regardless of language, a common "not face" did indeed present itself. It consisted of the furrowed brows of "anger," the elevated chin seen in "disgust" and the tightly pressed lips of "contempt." Like so:
The universal "not face."
Image credit: The University of Ohio
Prof. Martinez says of the results:
"To our knowledge, this is the first evidence that the facial expressions we use to communicate negative moral judgment have been compounded into a unique, universal part of language."
To further investigate how deeply ingrained the "not face" is, the team turned to computer analysis.
Language is spoken at a frequency of 3-8 Hz, in other words, syllables flow from the speaker's mouth at a rate of between 3 and 8 per second. Previous studies have inferred that our brains are programmed to recognize grammatical constructions of this frequency as language.
The team found that the "not face" appeared in the same frequency range as spoken language, across all four language types. This adds to the evidence that the "not face" is embedded as part of the language itself.
Groundbreaking sign language discovery
The team also made an interesting finding in regards to ASL. In ASL, the word "not" can be signed with the hands, or it can simply be denoted by a shake of the head. What Prof. Martinez and his team found was that the "not face" was occasionally used without the sign for "not" or a shake of the head.
Prof. Martinez explains: "Sometimes, the only way you can tell that the meaning of the sentence is negative is that person made the 'not face' when they signed it."
The study gives a fascinating glimpse into humanity's ancient modes of communication. The authors conclude their research:
"These results provide evidence for the hypothesis that some components of human language have evolved from facial expressions of emotion, and suggest an evolutionary route for the emergence of grammatical markers."
The present research was a painstaking ordeal involving the in-depth study of thousands of frames of film. However, now that the team has demonstrated that the experiment works, they hope to automate much of the leg work with facial recognition algorithms.
Automation will enable them to conduct the next phase of their investigation where they plan to analyze 1 billion frames of YouTube footage of people speaking.
Medical News Today recently covered research that asked why smiles, frowns and grimaces are contagious.