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Rational analysis of the selection task

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Rational analysis of the selection task. Oaksford and Chater (1994) ... Pretend you are a bouncer at the R&D pub... Actor/inquirer. A guy walks into a bar... – PowerPoint PPT presentation

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Title: Rational analysis of the selection task


1
Rational analysis of the selection task
  • Oaksford and Chater (1994)
  • Presented by
  • Bryan C. Russell

2
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
3
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)

4
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

5
Card probabilities
6
Card probabilities
  • Task Select card that maximally reduces
    hypothesis uncertainty

7
Entropy/uncertainty
8
Entropy/uncertainty
9
Entropy/uncertainty
10
Another experiment
  • Suppose you observe
  • TTHTHHTHHHHTHHTHTHHT

11
Another experiment
  • Suppose you observe
  • TTHTHHTHHHHTHHTHTHHT
  • HTHHTTHTHHTTTTTTTTTH

12
Another experiment
  • Suppose you observe
  • TTHTHHTHHHHTHHTHTHHT
  • HTHHTTHTHHTTTTTTTTTH

13
Mutual information
14
Application to selection task
a Pr(p)
15
Application to selection task
a Pr(p)
16
Model behavior
17
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

18
Model behavior
R
19
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

20
How do humans compare?
21
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22
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23
Analysis
  • Both humans and model accounts for the following
    information relationship
  • choose p gt choose q gt choose not-q gt choose not-p

24
Thematic selection task
  • If a person is drinking beer, then they must be
    over 20 years old

drinking sprite
25 years old
16 years old
drinking beer
25
Thematic selection task
  • If a person is over 20 years old, then they may
    drink a beer

drinking sprite
25 years old
16 years old
drinking beer
26
Rule types
  • Obligations if action (p), then must condition
    (q)
  • Permissions if condition (p), then may action (q)

27
Subject perspective for permission rule
  • Enforcer
  • Pretend you are a bouncer at the RD pub
  • Actor/inquirer
  • A guy walks into a bar

28
Utility-based model
  • Focus on rule-use, not rule-testing
  • Associate cost with turning over a card

29
Utility-based model
30
Performance of utility-based model
31
Comparison with humans
32
Andersons (1990) steps for rationality
  • Specify precisely the goals of the cognitive
    system
  • Develop a formal model of the environment to
    which the system is adapted
  • Make minimal assumptions about computational
    limitations

33
Andersons (1990) steps for rationality
  • Derive the optimal behavior function given the
    previous steps
  • Examine the empirical evidence to see whether the
    predictions of the behavioral function are
    confirmed
  • Rinse, lather, repeat, and refine the theory

34
Discussion questions
  • Why use a probabilistic framework for
    rationality?
  • Is the rarity assumption valid?
  • Is the selection task representative of
    accounting for rational thought? Is it
    exhaustive?
  • How does one learn the utility costs?
  • How does one learn Pr(p) and Pr(q)?
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