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The Somatic Marker Hypothesis:
Human Emotions in Decision-Making
Presented by Lin Xiao
Brain and Creativity Institute
University of Southern California
Most of us are taught from early on that :-logical, rational calculation forms the basis of sound decisions.-Emotion has no IQ.-Emotion can only cloud the mind and interfere with good judgment.
But what if we were wrong?!What if sound, rational decision making in fact depends on prior accurate emotional processing?
I will make the case that:
Decision-making is a process critically dependent on neural systems important for the processing of emotions.
Conscious knowledge alone is not sufficient for making advantageous decisions.
Emotion is not always beneficial to decision-making; sometimes it can be disruptive.
A Brief History
Phineas Gage was a dynamite worker, and survived an
explosion that blasted an iron-tamping bar through the front
of his head.
Before the accident, Phineas Gage was a man of normal intelligence, responsible, sociable, and popular among peers and friends.
He survived this accident with normal intelligence, memory, speech, sensation, and movement. However, his behavior changed completely:
He became irresponsible and untrustworthy.Impatient of restraint or advice when it conflicted with his desires.
A Brief History
A Brief History
Patients with Ventral Medial/Orbital
Prefrontal Cortex damaged
Before brain damage: Normal intelligence. After the damage: Normal intelligence.
But
Difficulties making good decisions in real-life. Their choices are no longer advantageous, and are remarkably different from the kinds of choices they are known to make in the pre-morbid period:
Their decisions and actions often lead to losses of diverse order, including:-losses in financial status-bankruptcies.-losses in social standing-involvement with unscrupulous people.-Break-up of family and distancing from friends.
Patients with Ventral Medial/Orbital
Prefrontal Cortex damaged
This particular class of patients presented a puzzling defect: difficult to explain their disturbances in terms of defects in knowledge, general intellectual compromise, language comprehension or expression, or in memory or attention.
However, their ability to express emotion and to experience feelings in appropriate social situations becomes compromised.
Along with normal intellect, these patients show: 1. Abnormalities in emotion and feeling. 2. Severe impairments in judgment and decision-making in real-life.
Patients with Ventral Medial/Orbital
Prefrontal Cortex damaged
Especially this latter observation was what led Antonio R. Damasio to propose what has become an influential neural theory of decision-making, the Somatic Marker Hypothesis (SMH).
The central feature of this theory is that emotion-related signals (somatic markers) assist cognitive processes in implementing decisions.
A further aspect of this theory is that these somatic markers can be non-conscious: they can bias behavior even when a person is not really aware of them.
Somatic Marker Hypothesis (SMH)
Definitions:
EMOTION as a collection of physiological changes in body and brain
states triggered in response to an event:
Some changes are non-perceptible to an external observer, e.g., heart
rate, skin conductance, endocrine release.
Some changes are perceptible to an external observer (e.g. skin
color, body posture, facial expression).
The signals generated by these changes towards the brain itself produce
changes perceptible to the individual and are ultimately perceived as a
FEELING .
Emotion= What an outside observer can see, or at least can measure.
Feeling= What the individual senses or subjectively reports.
Somatic Marker Hypothesis (SMH)
Testing the Somatic Marker Model:
-The Iowa Gambling Task (IGT) paradigm for
measuring decision-making.
Iowa Gambling Task (IGT)
Iowa Gambling Task (IGT)
Iowa Gambling Task (IGT)
DD
Gain per Card
$100
$1250
-$250
$100
$1250
-$250
$ 50
$250
+$250
$ 50
$250
+$250
AA BB CC
“Bad” Decks “Good” Decks
Loss per 10 Cards
Net per 10 Cards
5 sec
Onset of Card Selection
ANTICIPATORY SCR
(Before Choice)
REWARD/ PUNISHMENT SCR
(After Choice)
(a)
(b)
The Iowa Gambling Task (IGT)
Skin Conductance Response (SCR)
Bechara A, 1994
0 second 10 second 20 second
Card SelectionCard Selection Card Selection
R/P R/P R/PAnticipatory Anticipatory
Do these somatic (emotional) signals have to
be conscious?
No!
1. Somatic signals may bias decisions covertly.
2. Conscious knowledge alone is not sufficient
for making advantageous decisions.
Number of
Choices
From Decks
Anticipatory
SCR Level
Sequence of Card Selection
Controls
Did not Reach
Conceptual
Period
VMPC
Did Reach
Conceptual
Period
Bad Decks
Good Decks
Bad Decks
Good Decks
Knowledge Level
(a)
(b)
(c)
A Diagrammatic Summary of the Results of Bechara et al. (1997) Study
(d)
(e)
Anticipatory SCRs represent unconscious biases
that are linked to prior experiences with reward
and punishment.
Deprived of these biases, conscious knowledge of
what is right and what is wrong may become
available. However, by itself, this conscious
knowledge is not sufficient to ensure an
advantageous behavior.
Therefore, frontal patients may be fully aware of
what is right and what is wrong, but they fail to
act accordingly:
These patients can say “the right thing”, but they
do “the wrong thing”.
Modulating Factors
1.Time: information conveying immediacy (e.g.
getting a heart disease tomorrow) exerts a
stronger influence on decisions than information
conveying delayed/future outcomes (e.g. getting
a heart disease 20 years from now).
2.Probability: people prefer a sure gain over a
probabilistic one, or they avoid a sure loss and
prefer a probabilistic one instead.
3.Tangibility: people have an easier time
spending money on credit cards as opposed to
spending real money.
-
Reflective
Orbitofrontal /Ventromedial
System
Timeimmediate delayed
Frequencyhigh low
Magnitudehigh low
Relationconcrete abstract
Triggering somatic states
Strong Weak
+-
-+
+-
Summation:
Strong dominates Weak
Feedback:
Net Positive or Negative
Somatic State
Impulsive
Amygdala System
+-
Information conveying immediacy (near future), high probability
(certainty), or tangibility engages more posterior VMPC, whereas
information conveying delay (distant future), low probability, or
abstractness engages more anterior VMPC cortices (Bechara, 2005).
-
Reflective
Orbitofrontal /Ventromedial
System
Timeimmediate delayed
Frequencyhigh low
Magnitudehigh low
Relationconcrete abstract
Triggering somatic states
Strong Weak
+-
-+
+-
Summation:
Strong dominates Weak
Feedback:
Net Positive or Negative
Somatic State
Impulsive
Amygdala System
+-
The more posterior areas of the VMPC (e.g. Brodmann area 25)
are directly connected to brain structures involved in triggering or
representing somatic states, while access of more anterior areas is
poly-synaptic and indirect.
It follows that coupling of information to representations of somatic states via posterior VMPC is associated with relatively fast, effortless, and strong somatic signals, while the signaling via more anterior VMPC is relatively slow, effortful, and weak.
-
Reflective
Orbitofrontal /Ventromedial
System
Timeimmediate delayed
Frequencyhigh low
Magnitudehigh low
Relationconcrete abstract
Triggering somatic states
Strong Weak
+-
-+
+-
Summation:
Strong dominates Weak
Feedback:
Net Positive or Negative
Somatic State
Impulsive
Amygdala System
+-
The nearer, more certain or more tangible events possess stronger emotions/affects, and things that are far more distant in the future, far less probable, and far more abstract trigger much weaker responses.
-
Reflective
Orbitofrontal /Ventromedial
System
Timeimmediate delayed
Frequencyhigh low
Magnitudehigh low
Relationconcrete abstract
Triggering somatic states
Strong Weak
+-
-+
+-
Summation:
Strong dominates Weak
Feedback:
Net Positive or Negative
Somatic State
Impulsive
Amygdala System
+-
1.Time: information conveying immediacy (e.g.
getting a heart disease tomorrow) exerts a
stronger influence on decisions than information
conveying delayed outcomes (e.g. getting a heart
disease 20 years from now).
2.Probability: people prefer a sure gain over a
probabilistic one, or they avoid a sure loss and
prefer a probabilistic one instead.
3.Tangibility: people have an easier time
spending money on credit cards as opposed to
spending real money.
The Neuroanatomy of “Emotions” and “Feelings”
The Iowa Gambling Task in fMRI Images
From Li X, et al., (Submitted)
Is Emotion Always Beneficial to Decision-Making?
No!
Emotion can be disruptive to decision-making.
Risky Decision-making Task
Each participant was endowed with $20 of play money, which they
were told to treat as real because they would cash the amount they
were left with at the end of the study.
Participants were told that they would be making several rounds of
investment decisions, and that, in each round, they had to make a
decision between two options: invest $1 or not invest.
If the decision were not to invest, the task would advance to the
next round.
If the decision were to invest, they would hand over a dollar bill
to the experimenter.
The experimenter would then toss a coin in plain view of the subject.
If the outcome of the toss was heads (50% chance), they would
lose the $1 that was invested;
if the outcome of the toss was tails (50% chance), $2.50 would
be added to the participant’s account. The task would then
advance to the next round.
The task consisted of 20 rounds of investment
decisions.
The investment task was designed so that it
would behoove participants to invest in all
the 20 rounds because the expected value on
each round is higher if one invests ($1.25)
than if one does not ($1).
Risky Decision-making Task
Shiv B, 2005
Emotional reactions to the outcomes on preceding rounds affected decisions on subsequent rounds for normal participants and control patients, but not for target patients
Shiv B, 2005
Emotions play a major role in the interaction between environmental conditions and human decision processes, with neural systems carrying emotional signals providing valuable implicit or explicit knowledge for making fast and often advantageous decisions. But sometimes, these emotional signals interfere with rational decisions.
Thus it is not a simple issue of emotions are good or bad. It is a matter of discovering the circumstances in which emotions can be useful or disruptive, and using the reasoned coupling of circumstances and emotions as a guide to human decisions.
Knowledge
Cognition
Decisions
Actions
Affect
Emotion
Feelings
The process of decision-making is not just logical and computational but also emotional.
- -+++Immediacy Delay
DA
5-HT
ACDLPC
VMPC
A
Insula
Hyp
Striatum
Reflective
Impulsive
a. b. c.
During the process of weighing somatic responses, the immediate and future prospects of an option may trigger numerous somatic responses that conflict with each other. The end result is that an overall positive or negative somatic state emerges.
- -+++Immediacy Delay
DA
5-HT
ACDLPC
VMPC
A
Insula
Hyp
Striatum
Reflective
Impulsive
a. b. c.
Mechanisms that determine the nature of this overall somatic state (i.e., being positive or negative) are consistent with the principles of natural selection, i.e., survival of the fittest (Bechara & Damasio, 2005).
In other words, numerous and often conflicting somatic states may be triggered at the same time, but stronger ones gain selective advantage over weaker ones
- -+++Immediacy Delay
DA
5-HT
ACDLPC
VMPC
A
Insula
Hyp
Striatum
Reflective
Impulsive
a. b. c.
The final decision is determined by the relative strengths of the pain/pleasure signals triggered by immediate and future prospects.
- -+++Immediacy Delay
DA
5-HT
ACDLPC
VMPC
A
Insula
Hyp
Striatum
Reflective
Impulsive
a. b. c.
