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  1. 1. The Neural Representation of Decision- Making under Uncertainty Scott Huettel Psychology & Neuroscience Duke University
  2. 2. “…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)
  3. 3. “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
  4. 4. 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?
  5. 5. “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.” - Garner (1962). Uncertainty and Structure as Psychological Concepts, p. 3. Wendell “Tex” Garner
  6. 6. LPFC Huettel, Mack, & McCarthy (2002) Nature Neuroscience -0.025% 0.000% 0.025% 0.050% 0.075% 0.100% 0 4 8 12 16 7 6 5 4 3 2 1 BOLDSignalChange Sequence Length Lateral PFC LPFC
  7. 7. McCoy & Platt (2005) Nat Neuro Ubiquitous Risk Signals Preuschoff et al. (2007) J Neurosci Insula Huettel et al. (2005) J Neurosci Parietal Cortex Prefrontal Cortex Posterior Cingulate
  8. 8. From Glimcher & Rustichini (2004) Science.
  9. 9. Risky - Certain Ambiguous - CertainRisky - Risky Ambiguous - Risky Trial Types Trial Structure Decision (RT) Expectation (4.5-6s) Outcome (2s) Huettel et al. (2006) Neuron Risk vs. Ambiguity
  10. 10. pPAR LPFC aINS LPFC Signalchange(%) 0.12 BOLDParameters(a.u.) 20 AC AR RC RR AC AR RC RR 0.2 0.16 Time since trial onset (s) aINSpPAR AC AR RC RR Trial Type 20 20 L
  11. 11. Risk: Expected Utility Ambiguity: α – MaxMin Expected Utility Ambiguity Preferring Risk Preferring Ambiguity Averse Risk Preferring Ambiguity Preferring Risk Averse Ambiguity Averse Risk Averse Subjects (n=13)
  12. 12. Ambiguity Preference (AC+AR)–(RC+RR) Ambiguity preference (1-α) Risk preference (β) (RC+RR)-(AC+AR) Risk Preference LPFCaINSpPAR More (1)(0) Less More (3)(0) Less α - Ambiguity β - Risk Correlationwith EconomicPreference 0.0 0.2 0.4 0.6 0.8 1.0 pIFS pPAR Resampling Analysis LPFC Ambiguity… in Lateral Prefrontal Cortex?
  13. 13. Hsu et al. (2005) Science Ambiguity… in Orbitofrontal Cortex?
  14. 14. 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
  15. 15. Interim Take-Home Message Concepts from decision science are unlikely to reflect unitary psychological constructs nor single neural modules
  16. 16. Conditioning of Risk and Ambiguity Bach et al. (2009) J Neurosci Here, ambiguity reflects the expected revelation of information; i.e., a potentially known unknown.
  17. 17. Stimuli involving ambiguity evoked greater activation in dlPFC and PPC than those involving risk or ignorance. Bach et al. (2009) J Neurosci
  18. 18. pIFS Huettel & Misiurek (2004) In a task similar to an implicit Wisconsin Card Sorting Task (i.e., learning rules without immediate feedback)… …stimuli that eliminate potential rules evokes activation in lateral PFC (the posterior inferior frontal sulcus)… …proportional to the # eliminated rules.
  19. 19. 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
  20. 20. Kringelbach (2005) Nat. Rev. Neurosci Hsu et al. (2005) Science Punishm ent/ Aversion Plassmann et al. (2007) J. Neurosci. Reward/ Value
  21. 21. LPFC Huettel et al. (2006) Neuron Hsu et al. (2005) Science • Ambiguity effects in orbital PFC – Tasks (3): Gambles, knowledge, opponent – Activation preceded decision (slow) – Aversion led to increased activation – Subject sample: very ambiguity averse • Ambiguity effects in lateral PFC – Task (1): Gambles – Activation coincident with decision (fast) – Aversion led to decreased activation – Subject sample: ambiguity neutral Emotional aversion signal: pushes behavior away from ambiguous/risky options? Cognitive signal: supports creation of decision scenario under ambiguity?
  22. 22. 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. “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 Wendell “Tex” Garner
  23. 23. Acknowledgments Support • NIMH, NINDS, NIA • Duke Institute for Brain Sciences 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 Collaborators on these Projects • Gregory McCarthy • Michael Platt