Human Faces Can Express at Least 21 Distinct Emotions Alice Park @aliceparkny March 31, 2014
Distinct facial muscles were used to express
Leading scientific thinkers of their time, such as Aristotle,
Rene Descartes, Guillaume Duchenne, and Charles
Darwin, have long promoted the idea that there are a handful of basic emotions
that people express. In recent decades, that group has crystalized into six
core emotions: happiness, surprise, sadness, anger, fear, and disgust.
But there are clearly many shades of gray between those emotions. For example,
there’s the happy-because-I’m-eating-ice cream and the
happy-because-I-just-learned-I-got-a-surprise-marriage-proposal looks, each of
which is slightly different.
That’s what intrigued Aleix Martinez, associate
professor of electrical and computer engineering at Ohio State University. “Six
seemed a small number given the rainbow of possibilities of feeling and
expressing emotions,” he says.
Martinez wanted to know whether compound emotions, such as happy surprise, were
expressed using the same muscle movements of both happiness and surprise, or
whether the expression involved a unique set of muscles that represented some
amalgam of the two.
What he and his colleagues found was that the human face makes 21 different
emotional expressions – and each is different from the other. While some
represented combinations of emotions, each differed in terms of which muscles
And surprisingly, these facial expression patterns were remarkably consistent
across all 230 volunteers. For example, each showed happy surprise in the same
way that was distinct from both happiness and from surprise, and different
still from angry surprise.
Martinez broke down the facial expressions of 230 volunteers by applying his
engineering strategies. He and his colleagues gave each of the students, staff,
or faculty members who enrolled in the study different scenarios and asked them
to show how they would react in each one. They were told, for example, that they
had just learned they had been accepted to a graduate program, that someone had
told them a disgusting, but still funny joke, or that they had just smelled
something bad. The volunteers were allowed to practice their facial expressions
in front of a mirror before Martinez took pictures of their reactions.
He then computer-analyzed each of the 5,000 images, breaking them down by which
facial muscles the participants used. These were first defined in 1978 by
psychologist Paul Ekman, who
codified facial expressions in the Facial Action Coding System (FACS) by action units, or muscles or groups of muscles that
went into making facial expressions – such as lip parts (for showing
disgust), showing teeth (for expressing happiness), mouth stretch (for fear),
or eyelid tightening (for anger).
Not only are people able to make compound expressions consistently, but we are also able to read these emotions pretty
accurately as well. When we see someone who looks angrily surprised, for
example, we know that they aren’t happy about whatever unexpected event they
just experienced. “We don’t know for sure how much is learned or innate in
expressing these emotions,” says Martinez. “But what we do know is that a big
component has to be innate because otherwise different people would use
different muscles to show the same emotion.”
The results dovetail with recent findings that some cultures may already
recognize these more refined, and numerous expressions of emotions. In a study
among the remote Himba tribes in Namibia, for
example, researchers at Northeastern University reported that when they
provided tribe members with images of facial expressions of emotions, rather
than creating six neat piles of emotions, the members created many more. For
them, happy could be interpreted as anything from happy to laughing to wonder.
That should help to improve how studies of human emotions are conducted in
different cultures, says Martinez; his results suggest that the underlying
ability to express emotions may be similar around the world, but cultural
biases may simply define emotions in different ways – much the same way
that babies are born with the capacity to speak and make sounds for any
language, but are trained to speak their native tongue by what they hear around
Even more exciting for mental health experts is the possibility that this work
can teach them about when the processing and expression of human emotions goes
awry such as in depression. “It’s
important to understand which are categories of emotions that we have,” says
Martinez, so that experts can recognize the pathological ones. Expressing
emotions is generally a transient exercise, lasting milliseconds or up to a
minute. Those that linger longer, for hours or even days, tend to be considered
moods, and once these emotions persist for days, weeks or months, they can
become the subject of mental illness. So distinguishing how people express
themselves, and defining the categories of well-known and well-recognized
emotions, could lead to better understanding of which emotions can become detrimental
and even harmful.
Twenty facial expressions of basic and
compound emotion categories. From left to right and top to bottom, these
categories correspond to: happy, sad, fearful, angry, surprised, disgusted,
happily surprised, happily disgusted, sadly fearful, sadly angry, sadly
surprised, sadly disgusted, fearfully angry, fearfully surprised, fearfully
disgusted, angrily surprised, angrily disgusted, disgustedly surprised, hatred,
and awed. Credit: Aleix M. Martinez
To Really Read
Emotions, Look at Body Language,
Not Facial Expressions
By Laura Blue Nov. 30, 2012
We like to think we can read people like a book, relying mostly
on tell-tale facial expressions that give away the
emotions inside: the way the brows lift slightly with alarm, or the crow’s feet
that crinkle with a wide smile. But when it comes to the strongest emotions, we
read much less from facial expressions than we think we do. In fact, even
though we believe it’s the face that tells the story, we’re typically reading
something very different: body language and social cues.
That’s the new, counterintuitive finding from a study published this week in
the journal Science. Researchers from Princeton, New York University, and
the Hebrew University of Jerusalem presented volunteer study participants with a series of pictures showing people
experiencing extreme emotion, either positive or negative. The images included
professional tennis players who had
just won or lost a point in a major match, as well as people undergoing nipple
piercing, and those in the throes of orgasm.
In some of the images, researchers would only show the study participants a
face; in others, only a body; and in others still, both the body and the face.
You might think it’d be obvious from a face whether someone is in pain (having a nipple pierced) or whether
he has just won Wimbledon. But it turns out it isn’t.
“The striking finding was that our participants had no clue if the emotion was
positive or negative, when they were judging isolated faces,” says lead study
author Hillel Aviezer from Hebrew University in an email
response discussing the findings. “By contrast, when they were judging the body
(with no face), or the body with the face, they easily differentiated positive
from negative expressions.”
The findings are doubly surprising because the study participants themselves
were convinced that they recognized the emotions from the faces, not from body
language or contextual cues.
“They even had their own ‘mini theories’ about what part of the face was most
important – but this was all an illusion,” Aviezer says.
He adds that we do, of course, read a great deal of salient day-to-day
emotional information from faces — but only in certain situations. The
reliability of that transmission, for example, appears to break down when
emotions are at their strongest. The face contorts. We can tell that something
major has happened, but it’s tough to tell that something is dramatically
positive or devastatingly negative.
In the article, Aviezer and his colleagues liken the
muscles of the face to an audio speaker. As the volume is pushed to its
maximum, the quality of the signal becomes poor and the message becomes harder
to pick out.
There is a similar analogy to the emotional signals that we hear. We know that
the sound of gentle laughing conveys happiness and a gentle sob conveys sorrow.
But most of us find it difficult to distinguish a shriek of joy from a shriek
of fear. Since we often hear sounds without another contextual clue to explain
them — overheard from an adjacent room — we tend to accept that we can’t
tell positive from negative emotion in all cases. But we almost never see faces
without body language and a setting to accompany them. So we may fail to
realize that the face is less informative than usual when emotions run high.
Aviezer says his results suggest that the classic
textbook distinction between positive emotions and negative emotions may need
to be revised to incorporate the possibility that they may share more
underlying physiological features than we thought. That could have implications
for theories that link emotions to economics, social psychology, and
“I also think the findings may have some clinical applications,” he says.
“Consider populations such as individuals with autism or various
neuropsychiatric disorders. We know these people often have difficulties with
recognizing facial expressions,” he says. “Until now we have been trying to
help them by training them to better understand the isolated faces. But our
work suggests that perhaps we should zoom out a bit and teach them how to
recognize emotions from the full person in context.” That could provide a
broader range of therapies from which autistic children can draw, and, perhaps
Emotions May Not Be So Universal After All
Park @aliceparkny March 6, 2014
Our current understanding of facial expressions could
specific to Western cultures
Many Faces of Megan
Simon Gerzina Photography—Getty
From a very young age, infants have a way of making their
feelings known – contorted faces and howls indicate their displeasure
with a meal or a damp diaper, a gummy smile their contentment, and a furrowed
brow their puzzlement over a new discovery such as their thumb.
While it seems logical that these expressions are universal, the latest study
suggests they may not be. In fact, expressions of the major emotions –
happiness, sadness, anger and the like, may be strongly culturally driven.
Maria Gendron, a post doc in the lab of psychology
professor Lisa Feldman Barrett at Northeastern University, visited remote
tribes in Namibia to come to that conclusion. Gendron spent 18 days with the Himba, a people with little
exposure to the Western world. When members were asked to sort photos of six
people making six facial expressions of emotions, she expected to see six neat
piles of images.
Instead, she found that the tribal members created a multitude of piles, with
some images appearing in more than one. The same thing happened when she played
vocal sounds of emotions – the same sound appeared joyful to some and
more negative to others. When she and Barrett repeated the experiment in
Boston, there was more unanimity in the sorting.
That sunk the idea that emotional expressions were universal; the Himba, for example, saw what Westerners would view as happy
expressions as reflecting anything from happy to laughing to wonder.
They believe that the notion of universal facial expressions emerged from flaws
in the way the original theory was developed in the 1970s, when American
psychologist Paul Ekman traveled to Papua New Guinea to conduct a study similar to the one Gendron did. Ekman, however, asked the participants to
match images of facial expressions to six words or scenarios depicting the
emotions. That constraint, Barrett and Gendron, believe, implied a universality in emotional expressions
that may not have existed.
The findings aren’t the first to nibble away at some conventional wisdom about
how we express emotions. Recently, Scottish researchers at the University of
Glasgow questioned the
long-held belief that humans expressed six emotions – happy,
surprised, afraid, disgusted, angry and sad. Instead, they found that
similarities among some of them mean there are likely only four basic emotional
expressions – happy, sad, afraid/surprised, and angry/disgusted.
How we read and express how we feel, it seems, is strongly influenced by how
the people around us express how they feel. We feel what we see.