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This analysis by Bryan C. Russell delves into human decision-making through a probabilistic framework, focusing on the selection task. The study explores rules, hypotheses, assumptions, card probabilities, and model behaviors, examining how humans compare and decide based on information values. The rarity assumption is validated, showcasing the utility-based model for thematic selection tasks. Discussion points ponder using such a framework for rationality and if the selection task adequately represents rational thought.
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Rational analysis of the selection task Bryan C. Russell 9.012
Wason selection task • Rule: if there is an A on one side, then there is a 2 on the other side K 2 7 A
Another view of the task • Let rule be “if p then q” • Four types of cards • (p,q), (not-p,q), (p,not-q), (not-p,not-q) • Two hypotheses • MD: p,q are dependent (rule is true) • MI: p,q are independent (rule is false)
Assumptions • We can assign probabilities to the cards • Should reflect natural statistics of “if p then q” statements in nature • P(p | MD) = P(p | MI) = a • P(q | not-p,MD) = P(q | not-p,MI) = b
Card probabilities • Task: Select card that maximally reduces hypothesis uncertainty
Another experiment… • Suppose you observe: • TTHTHHTHHHHTHHTHTHHT
Another experiment… • Suppose you observe: • TTHTHHTHHHHTHHTHTHHT • HTHHTTHTHHTTTTTTTTTH
Another experiment… • Suppose you observe: • TTHTHHTHHHHTHHTHTHHT • HTHHTTHTHHTTTTTTTTTH
Application to selection task a = Pr(p)
Application to selection task a = Pr(p)
Observations • If Pr(q) is low, then choosing p card is informative • If Pr(p) and Pr(q) is low, then choosing q card is informative • If Pr(p) is high, then choosing not-q card is informative • not-p card is not informative (results in zero information) • P(MI) only scales information values
Rarity assumption • For selection task, in humans Pr(p) and Pr(q) are low • Expected information over region R • choose p: 0.76 • choose q: 0.20 • choose not-q: 0.09 • choose not-p: 0
Analysis • Both humans and model accounts for the following information relationship: • choose p > choose q > choose not-q > choose not-p
Discussion questions • Why use a probabilistic framework for rationality? • Is the selection task representative of accounting for rational thought? Is it exhaustive?