Expressing fear
enhances sensory
acquisition
Susskind et al., Nature Neuroscience, 11, 843-850 (2008)
Presented by: Kara Hawkins
Overview of Susskind’s Story

Everybody talks about the behavioural & neural
bases of emotional expression recognition


Ekman, Izard, Adolphs, Gallese
But what about the production of emotional
expression?
 Why
do our facial expressions look the way they do?
 Darwin (origin of facial expressions)



Principle of form
Principle of function
Provide evidence for Darwin’s view that facial
expressions look the way that they do because
their form serves a function that is beneficial to
the survival of the organism
Paul Ekman


Social communication
Cultural invariance in the
recognition of facial
expressions
Ekman, P. & Friesen, W. J. Pers. Soc. Psychol., 17 124-129 (1971)
Carroll E. Izard


Innate & universal facial
expressions
Developmental & crosscultural research
Izard, C.E. Psychol. Bull., 115, 288-299 (1994)
Ralph Adolphs

Demonstrated the
existence of
dedicated neural
substrates for the
recognition of emotion
from facial
expressions
Adolphs, R. Behav. Cogn. Neurosci. Rev. 1, 21-62 (2002)
Adolphs,R. Behav. Cogn. Neurosci. Rev. 1, 21-62 (2002)
Ralph Adolphs


Demonstrated the
existence of
dedicated neural
substrates for the
recognition of emotion
from facial
expressions
Suggested a common
circuitry for perceiving
& generating facial
expressions
Adolphs, R. Behav. Cogn. Neurosci. Rev. 1, 21-62 (2002)
Vittorio Gallese
Suggested that emotion
recognition is
“accomplished through
Gallese & Adolphs have begunmirroring
to consider
some
of theto
motor
actions
mechanisms involved in the production
of facial
infer the mental
states of
expressions, however they have
not addressed the
others”
question of why particular facial
muscleemotional
actions are
 Shared
associated with specific emotional
states result from
experiences
simulated action and thus
emotional resonance
(empathy) in the observer

Gallese, V. Philos. Trans. R. Soc. B. Biol. Sci., 362, 659-669 (2007)
Why do we look the way we do in
certain situations?
Whalen P.J. & Kleck R.E. Nat. Neurosci., 11, 739-740 (2008)
Charles Darwin

This sort of question was
first seriously asked by
Darwin (The Expression of
the Emotions in Man and
Animals, 1872/1998)

Facial expressions
originated for the purpose
of modifying
preparedness for
perception & action (i.e.
augmenting or
diminishing exposure to
environmental stimuli)
Joshua Susskind (et al.)



Sought evidence for two
of Darwin’s principles
1) Principle of form:
Emotions with opposite
functions are opposites in
facial action
2) Principle of function:
Facial expressions
originate in action
patterns serving adaptive
information processing
1) Principle of form
Used a computer-graphics based model of
facial appearance to examine the action
tendencies underlying and opposing fear
expressions
 Specifically interested in the physical
appearance of the facial expression of fear

Face Stimuli

8 face exemplars for each of the 6 basic emotions were
used to train the appearance model
Computer model



Represents each face as a vector in a
multidimensional space, coding variations is
shape & surface reflectance
Expression prototypes for fear & disgust were
created by averaging the vector representations
of all exemplars from these two categories
Faces were then synthesized at successive
intervals along “expression trajectories” (from
the prototypical expression to the
antiprototypical expression, i.e. an expression
containing opposing shape & surface reflectance
features)
Prototypical fear
Prototypical disgust


Antiprototypical fear
Antiprototypical disgust
Fear antiprototypes were most similar in structure to
disgust (r = 0.69)
Disgust antiprototypes were most similar to fear (r = 0.69)
and surprise (r = 0.70)
Subjective ratings
Fear antiprototype was rated maximally as
disgust
 Disgust antiprototype was rated maximally
as fear

Vector flow fields

Derived from the surface deformations that
occur as the face moves from:
In
sum, according
animation
Antifear
to fear to this computer
Antidisgust
tomodel,
disgust
the physical appearance (form) of fear, an emotion
associated with sensory vigilance, opposes the
physical appearance of disgust, an emotion associated
with sensory rejection.
Spreading longitudinal action
Contracting longitudinal action
2) Principle of function



Does this opposition in the physical appearance
of facial expressions of fear & disgust reflect
evolutionarily adaptive action tendencies?
If so, these expressions should retain some
residue of this function
Several studies were conducted to measure
differences in sensory regulation when the face
is posed to simulate the expression of fear and
when it is posed to simulate the expression of
disgust
Visual-field estimation experiment
Fear
135°
45°
• Also demonstrated that participants could detect
Neutral
baseline
objects at farther eccentricities in the upper visual
field during the fear condition
315°demonstrate
Vertical eye-sizethat fear
• Together,
225° these results
expressions enhance andrelative
disgust expression reduce
to neutral
the overall size of the visual field & stimulusDisgust
detection in the upper visual field.
Size of upper-visual field
relative to neutral
Eye movement experiment
Reliably faster than
neutral expressions
Both average & peak velocities
increased from disgust to fear
According to these results, expressions of fear
enhance and expressions of disgust decrease the
velocity of horizontal saccadic eye movements during
target localization.
Pronounced slowing
relative to neutral expressions
Nasal inspiration experiment
Increased mean air-flow
velocity over time
Increased inspiration volume
Since changes in air intake can be explained by a
variety of factors & may not necessarily reflect
structural changes in sensory capacity, the authors
decided to expand upon these findings by taking a look
at changes in the internal anatomy of the nasal
passages.
Decreased mean air-flow
velocity over time
Decreased inspiration volume
MRI of nasal passage: case study
Fearful axial slice
Disgust
Closed
Disgusted axial slice
Neutral
Fear
Dilated
MRI of nasal passage: case study
These results indicate that fearful facial expressions
facilitate nasal passage dilation, while disgusted facial
expressions result in sealing off these nasal passages,
which normally remain open. These changes in nasal
anatomy may be responsible for the changes in nasal
inspiration revealed in the previous experiment
Volume of air cavity in ventral
portion of nasal passages
Average overall air cavity
volume
Summary of support for Darwin’s
principles
Fear & disgust were shown to be near
opposites in form, supported by opposing
action patterns
 A parallel opposition in function between
fear & disgust was reveled by evidence for
enhanced visual-field size, saccadic
velocity, & nasal inspiration capacity in
fear & the direct inverse in disgust

What do these results mean?



The authors suggest that human facial
expressions likely originated in an innate
functional capacity to alter sensory processing &
sensory exposure (i.e. egocentric function)
But they are maintained & have been further
shaped based on social pressures (i.e.
empathetic function)
In other words, the functional & signal
(communication) value of facial expressions
have probably co-evolved such that the
functional importance for the sender is coupled
with communicative importance for the receiver
Non-human primates


Idea supported by
observing facial
expressions in nonhuman primates
These expressions
serve as innate
protective reflexes,
but like human
expressions they
have become
important for social
communication
Andrew, R.J. Science, 142, 1034-1041 (1963); Whalen P.J. & Kleck R.E. Nat. Neurosci., 11, 739-740 (2008)
Take home message
Facial expressions may have originally
evolved based on their adaptive role in
preparing the organism for perception &
action
 It is likely, however, that the form &
function of facial expressions in the
present day reflect selection pressures
from both biological & social sources

Thank You!