The Neural Representation of DecisionMaking under Uncertainty
Scott Huettel
Psychology & Neuroscience
Duke University
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Scott Huettel, Duke University
“…there are known knowns; there are things we
know we know.
We also know there are known unknowns; that is to
say we know there are some things we do not know.
But there are also unknown unknowns -- the ones
we don't know we don't know.”
- Rumsfeld (2003, in press)
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Scott Huettel, Duke University
“To preserve the distinction… between the measurable uncertainty and
an unmeasurable one we may use the term ‘risk’ to designate the
former and the term ‘uncertainty’ for the latter. …
It is this [type of] uncertainty which has been neglected in economic
theory, and which we propose to put in its rightful place.”
F. H. Knight (1921)
Risk, Uncertainty, & Profit
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Scott Huettel, Duke University
Outline of the Talk
• Uncertainty defined
• Case study: Ambiguity
– Contributions of lateral prefrontal, parietal cortex?
– Contributions of orbitofrontal cortex, amygdala?
• Discussion: What should neuroscience seek?
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Scott Huettel, Duke University
“Information occurs only if there
exists some a priori uncertainty, and
the amount of information is
determined by the amount of the
uncertainty – or, more exactly, it is
determined by the amount by which
the uncertainty has been reduced.”
Wendell “Tex” Garner
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- Garner (1962). Uncertainty and Structure
as Psychological Concepts, p. 3.
Scott Huettel, Duke University
@ Decision Neuroscience
Scott Huettel, Duke University
Lateral PFC
Sequence
Length
LPFC
BOLD Signal Change
0.100%
7
6
5
4
3
2
1
0.075%
0.050%
0.025%
0.000%
0
4
8
12
16
-0.025%
LPFC
Huettel, Mack, & McCarthy (2002) Nature Neuroscience
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Scott Huettel, Duke University
Ubiquitous Risk Signals
Insula
Posterior Cingulate
Preuschoff et al. (2007) J Neurosci
Parietal Cortex
McCoy & Platt (2005) Nat Neuro
Prefrontal Cortex
Huettel et al. (2005) J Neurosci
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Scott Huettel, Duke University
From Glimcher & Rustichini (2004) Science.
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Scott Huettel, Duke University
Risk vs. Ambiguity
Trial Types
Risky - Certain
Risky - Risky
Ambiguous - Certain
Ambiguous - Risky
Trial Structure
Decision (RT)
Expectation
(4.5-6s)
Outcome (2s)
Huettel et al. (2006) Neuron
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Scott Huettel, Duke University
L
20
BOLD Parameters (a.u.)
aINS
Signal change (%)
LPFC
LPFC
0.12
AC
AR
RC
RR
AC
AR
RC
RR
AC
AR
RC
RR
pPAR
aINS
0.16
20
pPAR
0.2
Time since trial onset (s)
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20
Trial Type
Scott Huettel, Duke University
Risk: Expected Utility
Ambiguity: α – MaxMin Expected Utility
Ambiguity Averse
Risk Averse
Ambiguity Averse
Risk Preferring
Ambiguity Preferring
Risk Averse
Ambiguity Preferring
Risk Preferring
Subjects
(n=13)
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Scott Huettel, Duke University
Ambiguity… in Lateral Prefrontal Cortex?
(0) Less
More (3)
Correlation with
Economic Preference
More (1)
(RC + RR) - (AC + AR)
(AC + AR) – (RC + RR)
(0) Less
Risk Preference
aINS
LPFC
Ambiguity Preference
1.0
α - Ambiguity
0.8
0.6
0.4
0.2
0.0
LPFC
pIFS
pPAR
β - Risk
pPAR
Resampling Analysis
Ambiguity preference (1-α)
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Risk preference (β)
Scott Huettel, Duke University
Ambiguity… in Orbitofrontal Cortex?
Hsu et al. (2005) Science
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Scott Huettel, Duke University
Evidence from Cognitive Neuroscience
• Lateral prefrontal cortex
– Important for establishing rules for behavior
– Implicated in reasoning, response selection
• Orbitofrontal cortex
– Important for learning about (aversive) stimuli
– Implicated in inhibition of behavior
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Scott Huettel, Duke University
Interim Take-Home Message
Concepts from decision science are unlikely
to reflect unitary psychological constructs
nor single neural modules
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Scott Huettel, Duke University
Conditioning of Risk and Ambiguity
Here, ambiguity reflects the expected
revelation of information;
i.e., a potentially known unknown.
Bach et al. (2009) J Neurosci
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Scott Huettel, Duke University
Stimuli involving ambiguity
evoked greater activation in
dlPFC and PPC than those
involving risk or ignorance.
Bach et al. (2009) J Neurosci
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Scott Huettel, Duke University
In a task similar to an implicit Wisconsin
Card Sorting Task (i.e., learning rules
without immediate feedback)…
pIFS
…stimuli that eliminate potential rules
evokes activation in lateral PFC
(the posterior inferior frontal sulcus)…
…proportional to the # eliminated rules.
Huettel & Misiurek (2004)
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Scott Huettel, Duke University
Ventral PFC Damage Increases Risk Seeking
Clark et al. (2008) Brain
Cf. Goel et al. (2007) Cerebral Cortex, who argue for potential laterality
effects in reasoning: RH impairs under incomplete information
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Scott Huettel, Duke University
Reward /
Value
Kringelbach (2005) Nat. Rev. Neurosci
Hsu et al. (2005) Science
Plassmann et al. (2007) J. Neurosci.
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Scott Huettel, Duke University
• Ambiguity effects in orbital PFC
– Tasks (3): Gambles, knowledge, opponent
Emotional aversion
signal:preceded
pushes behavior
– Activation
decision (slow)
away from–ambiguous/risky
options?activation
Aversion led to increased
– Subject sample: very ambiguity averse
Hsu et al. (2005) Science
• Ambiguity effects in lateral PFC
– Task (1): Gambles
Cognitive signal:
supports creation
of decision
– Activation
coincident
with decision (fast)
scenario
under ambiguity?
– Aversion
led to decreased activation
– Subject sample: ambiguity neutral
LPFC
Huettel et al. (2006) Neuron
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Scott Huettel, Duke University
A Lesson from Psychology… for Neuroeconomics?
“A concept that is synonymous with a single
operation is nothing more than a
restatement of an experimental result. But
a concept that arises as a consequence of
converging operations has a reality that is
independent of any single experimental
observation.
Wendell “Tex” Garner
“But before we can get convergence, we must
introduce variation in our experimental
procedures. … Stabilizing on a few
techniques… [is] utterly self-defeating…
because it completely drops the critical part
from critical realism.”
The Processing of Information and Structure p. 187
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Scott Huettel, Duke University
Acknowledgments
Collaborators on these Projects
• Gregory McCarthy
• Michael Platt
Laboratory Members
• McKell Carter
• Chris Coutlee
• John Clithero
• Debra Henninger
• O. Mullette-Gillman
• Brandi Newell
• Allison Scott
• David Smith
• Adrienne Taren
• Vinod Venkatraman
• Richard Yaxley
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neuroeconomics.duke.edu
Support
• NIMH, NINDS, NIA
• Duke Institute for Brain Sciences
Scott Huettel, Duke University