Decision-making is usually a secondary topic in psychology, relegated to the last chapters of textbooks. Most of the time these chapters acknowledge the failure of the “homo economicus” model and propose to understand human irrationality as the product of heuristic and biases, which may be rational under certain environmental conditions. Psychology pictures decision-making as a deliberative task, studied by multiple-choice tests using the traditional paper and pen method. Psychological research on decision-making assumes that the subjects’ competence in probabilistic reasoning – as revealed by these tests – is a good description of their decision-making capacities. This conception takes for granted (1) that the process of reasoning about action is identical to the process of decision-making and (2) that psychology documents either human failures to comply with rational-choice standards or how mental mechanisms are ecologically rational. In this talk, I argue that decision neuroscience (“neuroeconomics”) may suggest another approach for the study and the nature of decision-making. Research in this field show that information processing in decision is affective, embodied and prosocial: Evolutionary older neural structures, such as the limbic system or dopaminergic neurons, are highly involved in subjective risk and certainty assessment; somatosensory information is integrated in prefrontal areas and helps evaluating choices; In games where players may adopt fair or unfair attitudes, the first ones tend to be more frequent and the second ones elicit emotionally negative reaction. Moreover, I suggest (against bounded rationality) that these mechanisms achieve near-optimality in social decision-making and (against ecological rationality) that this optimality is not fitness-enhancing. Consequently, I argue that the study of decision-making should be construed as an investigation into “natural rationality” (the mechanisms by which cognitive agents make decisions) and that decision-making should be a central concern for psychology.

1. Natural Rationality:
Beyond Bounded and Ecological Rationality
Benoit Hardy-Vallée Department of Philosophy
University of Toronto
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2. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
‘standard conception’ of
decision-making
problems
descriptive
conceptual
normative
vs.
‘natural rationality’
problems
descriptive
conceptual
normative
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3. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Reasoning and decision making are high-level cognitive skills
- (Johnson-Laird & Shafir, 1993, p. 1)
Decisions . . . are often reached by focusing on reasons that
justify the selection of one option over another
- (Shafir et al., 1993, p. 34)
special edition of Cognition on decision-making (volume 49, issues 1-2, Pages 1-187
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4. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Paper and pen method
Symmetry between reasoning about action
and deciding
Folk-psychological
'Sense-Model-Plan-Act' picture
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5. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Robotics:
distributed architectures
coordination of multiple modules
Psychology:
sensorimotor simulation
affective processing
confabulation
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6. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
(…) a widely used text of graduate- level readings in
cognitive psychology, (Sternberg & Wagner, 1999) devotes
the ninth of eleven chapters to quot;Reasoning, Judgment, and
Decision Making,quot; (...) A leading undergraduate cognitive
psychology text (Goldstein, 2005) placed quot;Reasoning and
Decision Makingquot; the last of twelve chapters. (...) in a
leading behavioral psychology text (Mazur, 2002), choice is
covered in the last of fourteen chapters, and is limited to a
review of the literature on choice between concurrent
reinforcement schedules and the capacity to defer
gratification
(Gintis, 2007, pp. 1-2)
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7. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Psychology
categorization, inference, perception, emotion, personality make no
sense without DM capacity
Biology
decisions increase fitness
natural selection preserves good decision-makers
“Genes are the primary policy-makers; brains are the
executives”. (Dawkins)
“brains are ineluctably structured to make, on balance,
fitness-enhancing decisions in the face of the various
constellations of sensory inputs their bearers commonly
experience” (Gintis, 2007, p. 3)
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8. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Simplified account of Rationality
P1: If humans are rational, they comply with Rational-Choice Theory
P2: Humans do not comply with Rational-Choice Theory
C: Humans are not rational
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9. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Problems with P1 P1: If humans are rational, they comply with Rational-Choice Theory
RCT can be demanding
There is no one unique rational solutions in
repeated games
P2: Humans do not comply with Rational-Choice Theory
Problems with P2
they fail to make linguistic inferences
they reach market equilibriums in
experimental games
when we take non monetary good into account,
subject's behavior make sense
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10. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Ultimatum
Game
Proposer
Responder
$9/$1 $8/$2.... ... ...$1/$9
Accept/reject
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11. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Ultimatum Game
‘unfair’ offers trigger moral disgust and cognitive conflict
Sanfey, A. G., Rilling, J. K., Aronson, J. A., Nystrom, L. E., & Cohen, J. D. (2003).The neural basis of economic decision-making in the Ultimatum Game. Science, 300(5626), 1755-1758.
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12. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Risk vs. ambiguity
greater activation in response to risk than in response to ambiguity.
reward
computation
greater activation in response to ambiguity than in response to risk.
fear/vigileance “Affective forecasting”
Hsu, M., Bhatt, M., Adolphs, R., Tranel, D., & Camerer, C. F. (2005). Neural systems responding to degrees of uncertainty in human decision-making.
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Science, 310(5754), 1680-1683.

13. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Problems with conclusion C: Humans are not rational
if we are not, who is ?
why behavioral ecology is predictive
when classical economics is not?
A completely irrational species would have
been eliminated by natural selection
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14. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Bounded Rationality
‘cognitive illusions’
deviations
“deviations of actual behavior from the normative
model are too widespread to be ignored, too
systematic to be dismissed as random error, and too
fundamental to be accommodated by relaxing the
normative system. (…) the normative and the
descriptive cannot be reconciled”
(Tversky & Kahneman, 1986, p. s272)
Ecological Rationality
fitness maximization
optimality in Environment of
Evolutionary Adaptation (EEA)
“Ultimately, ecological rationality depends on
decision making that furthers an organism's
adaptive goals in the physical or social
environment”
(Gigerenzer & Todd, 1999, p. 364)
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15. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Descriptive
Conceptual
Normative
Natural Rationality
The descriptive and normative studies of neuro-
behavioral mechanisms of decision-making
- between optimism and pessimism
- no presupposition of fitness or cognitive illusions
- not based on folkpsychology
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16. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Descriptive
Conceptual
Normative
[Regret forecasting]
Counterfactual
Utility
[regrets]
[Affective forecasting]
[Regret /rejoicing]
Predicted
Utility
Remembered
Experienced
Utility
Utility
[prediction error]
Decision [Hedonic affect]
Utility
[Valuation]
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17. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Descriptive
Conceptual
Normative
Language
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18. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Descriptive
Conceptual
Normative
DM should be “the central organizing
principle of psychology” (Gintis, 2007, p. 1).
DM should not be studied like a separate
topic (e.g. perception), an occasional activity
(e.g. chess-playing) or a high-level
competence (e.g. logical inference)
Psychology should be the science of the mechanisms (normal and abnormal),
development, individual and cultural variations, and neural implementation of
decision-making in humans and animals.
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19. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
Descriptive
Conceptual
Normative
2 ways to evaluate mechanisms
Internal: coherence between decision,
predicted, rembered, counterfactual utility
External: efficiency and effectiveness of neural
mechanisms
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20. Introduction Standard Descritptive Conceptual Normative Natural Rationality Conclusion
“creatures inveterately wrong in their inductions have
a pathetic but praiseworthy tendency to die out
before reproducing their kind”
- (Quine, 1969, p. 126)
disputable for inductions, much less for decisions
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21. Thanks !
ben.hardy.vallee@utoronto.ca
Homepage
http://decisis.net
Natural Rationality Blog:
http://naturalrationality.blogspot.com
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