The document discusses research into facial expressions in both humans and dogs. It describes Charles Darwin's theory that facial expressions are innate and evolved to communicate emotions. Recent work supports this theory. The Facial Action Coding System was developed to categorize facial movements based on the contracting muscles. Six universal human emotions - happiness, sadness, surprise, fear, disgust, and anger - each correspond to distinct facial expressions involving specific muscles. Additional research found that dogs also use facial expressions like ear positioning to communicate emotions when seeing their owner, a stranger, or disliked objects.

1. Facial expressions and
emotion

2. Why do we use facial
expressions?
Source: www.scientificamerican.com
The ability to communicate subtle emotions with
a simple raised eyebrow or curl of the lip may be
innate.
Charles Darwin was one of the first to propose
this theory in his book The Expression of the
Emotions in Man and Animals, published in
1871, in which he wrote: “The young and the old
of widely different races, both with man and
animals, express the same state of mind by the
same movements.”
Recent work supports Darwin’s theory that
smiles, grimaces and more nuanced expressions
are hardwired—an artifact of living in social
groups.
Because humans depend on one another for
survival,
we
must
communicate;
facial
expressions may have evolved as efficient ways
to telegraph feelings and intentions.

3. Facial Action Coding System
Source: www.face-and-emotion.com
The Facial Action Coding System (FACS) is a
detailed, technical guide that explains how to
categorize facial behaviors based on the muscles that
produce
Paul Ekman and W.V. Friesen developed the original
FACS in the 1970s by determining how the contraction
of each facial muscle (singly and in combination with
other muscles) changes the appearance of the face.
They examined videotapes of facial behavior to identify
the specific changes that occurred with muscular
contractions and how best to differentiate one from
another.
They associated the appearance changes with the
action of muscles that produced them by studying
anatomy, reproducing the appearances, and palpating
their faces.
Their goal was to create a reliable means for skilled
human scorers to determine the category or categories
in which to fit each facial behavior. The FACS Manual
was first published in a loose-leaf version with video or
film supplements in 1978.

4. Six universal emotions
Source: www.nbb.cornell.edu
Psychological research has classified six facial expressions which correspond to distinct
universal emotions: disgust, sadness, happiness, fear, anger.
EXPRESSION
MOTION CUES
PSEUDO-MUSCLES USED
Happiness
raising and lowering of mouth corners
6 linear muscles
Sadness
lowering of mouth corners
raise inner portion of brows
6 linear muscles
Surprise
brows arch
eyes open wide to expose more white
jaw drops slightly
3 linear muscles
Fear
brows raised
eyes open
mouth opens slightly
5 linear muscles
1 sphincter for the mouth
Disgust
upper lip is raised
nose bridge is wrinkled
cheeks raised
6 linear muscles
Anger
brows lowered
lips pressed firmly
eyes bulging
4 linear muscles
1 sphincter for the mouth

5. Canines use expressions to
show their emotions
Source: www.dailymail.co.uk
'Dogs’ ears are prominent features used to convey
emotional expression, therefore our results suggest
that dogs were more cautious toward unfamiliar people.
'In contrast, eyebrow movement might indicate a
visible response whereby dogs attempted to look at
their owners more intently.'
The results of the study were published in the journal
Behavioural Processes.
The researchers placed 12 dogs in a room divided by a
partition with curtains that opened briefly to allow the
dogs to glimpse what was on the other side, while highspeed cameras tracked their facial expressions.
The research also found that dogs raise their left ear
when meeting a stranger for the first time and raise
their right ear when they see an object they don't like,
such as nail clippers.

6. Canines use expressions to
show their emotions
Source: www.dailymail.co.uk
Coloured stickers were placed on the dogs' faces, which
were picked up by the camera when the expression changed.
When the curtain opened, their owner, a stranger, a toy or an
item they did not like was on the other side.
The researchers found that the dogs moved their eyebrows
upwards whenever they saw someone behind the screen, but
far more when it was their owner, particularly on the left side.
They now believe the changes on different sides of their
faces are a reflection of activity in key parts of the brain that
control emotions.
They also say it could be because the animals were
experiencing conflicted emotions - joy at seeing their owner
but sadness at not being able to reach them through the
partition. Dr Nagasawa said: 'One explanation for this result is
that presentation of the owner elicited both negative and
positive emotions.