Reasoning & Decision making

Reasoning & Decision Reasoning & Decision makingmaking

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ReasoningReasoning

Information

Conclusion

Reasoning - deductiveReasoning - deductive

Information

Conclusion

Premise 1

Premise 2

…….

Premise n

Conclusion

Valid deductions = if premises true, then conclusion true

A deduction can be valid even if premises are false

Only form matters, not content

Reasoning - inductiveReasoning - inductive

Information

Conclusion

Inductive reasoning goes beyond the data

Conclusions never follow definitely from observations

Deduction - SyllogismsDeduction - Syllogisms

Categorical syllogisms- Deductions involving All, No, Some

All A are B All students are smart peopleAll B are C All smart people are richTherefore, all A are C Therefore, all students are rich

Conditional syllogisms - Deductions involving If…Then

If p then q If you talk at the movies you go to prison p You talk at the movies Therefore q You go to prison

Categorical SyllogismsCategorical Syllogisms

Valid and invalid categorical syllogisms

Valid Invalid

1 Some A are B 1 All A are B2 All B are C 2 Some B are CCon Therefore some A are C Con Therefore, some A are C

Some cats are lazy All cats are lazy All who are lazy are dogs Some who are lazy are dogsTherefore some cats are dogs Therefore some cats are dogs

Valid, despite false premise


What kind of errors do people make?- Belief bias

- If conclusion true, then syllogism valid

No A are BSome C are BTherefore some A are not CInvalid

A BNo babies are evil No heroin is healthySome dogs are evil Some chemicals are healthyTherefore some babies are not dogs Therefore some heroin is not chemicals

People judge A as valid more often than B, more believable conclusion


Conditional SyllogismsConditional SyllogismsPremises Conclusion Valid Performance

If p then qp q Yes 97 %

If p then qNot q Not p Yes 60%

If p then qq p No 40%

If p then qNot p Not q No 40%

Conditional SyllogismsConditional Syllogisms

Why do people make errors in conditional reasoning?

- One reason is lack of falsification strategies

- which is affected by the format of the problem

To see this, we will look at the Wason four-card problem

Wason four-card problemWason four-card problem

AA PP 66 33

Indicate the minimum number of cards you Indicate the minimum number of cards you have to turn to test the rule:have to turn to test the rule:

If there is a vowel on one side, If there is a vowel on one side, then there is an even number on the then there is an even number on the other side.other side.

Potential falsifiers

Wason four-card problemWason four-card problem

AA PP 66 33

If there is a vowel on one side, If there is a vowel on one side, then there is an even number on the then there is an even number on the other side.other side.

89%89% 16%

62%

16% 62% 2

5% 2

5%

Beer problemBeer problem

BeerBeer

SodaSoda

27 27

yearsyears

15 15 yearsyears

If a person is drinking beer, If a person is drinking beer, then he/she must be at least 19 years then he/she must be at least 19 years old.old.

Results – beer vs. abstract Results – beer vs. abstract (Griggs & Cox, 1982)(Griggs & Cox, 1982)

BeerBeerSodaSoda

27 27

yearsyears

15 15

yearsyears

AAPP

66 33

TheoriesTheories

Why is the beer task easier?Why is the beer task easier?

Pragmatic reasoning schema (permissions) Pragmatic reasoning schema (permissions)

- people are familiar with checking permissions- people are familiar with checking permissions

Cheating detection - Social exchange theory Cheating detection - Social exchange theory

- In order to monitor social exchange, people have - In order to monitor social exchange, people have developed cheating detection mechanisms that do developed cheating detection mechanisms that do

not not presuppose familaritypresuppose familarity

Permissions Permissions (Cheng & Holyoak, 1985)(Cheng & Holyoak, 1985)

EnterEnter

TransientTransient

CholeraCholera

TyphoisTyphois

HepatitisHepatitis

TyphoidTyphoid

HepatitisHepatitis

If one side says ”Enter”, If one side says ”Enter”, then the other says ”Cholera”then the other says ”Cholera”

A - Tropical diseases

B - Inoculations to ensure protection against disease

ResultsResults

Checking for inoculations indirectly emphasizes to check for permission to enter the country.

This ”permission” group performs much better.

Cheating Cheating (Cosmides & Tooby, 1992)(Cosmides & Tooby, 1992)

Found high performance in conditions that Found high performance in conditions that were unfamiliar to the participants and were unfamiliar to the participants and involved cheating.involved cheating.

Non-cheating situations reduced performance.Non-cheating situations reduced performance.

Permission schema or cheating detection?Permission schema or cheating detection?

- support for both accounts- support for both accounts

InductionInduction

Observation:Everytime I have met John he is rude. And Steve says the same thing about John.

Conclusion:John is a rude person.

Observation:Only humans seem to use language.

Conclusion:Humans have specially developed language mechanisms that other species do not have.

Strength of inductionStrength of induction

Representativeness Studying aeroplanes does not tell you much about

eagles.

Frequency A replicated experiment is better than an unreplicated.

Quality An astronomical story is more coherent than an astrological.

HeuristicsHeuristics

Some errors in inductive reasoning may be due to heuristics (even though the heuristics themselves may often be useful)

Heuristics - ”Rules of thumb”, ”shortcuts”- Can be adaptive, can lead to error- Computationally attractive

- Availability heuristic- Representativeness heuristic- Commitment heuristic

Availability heuristicAvailability heuristic

Which is a more likely cause of death?

or

Tornado Asthma

Asthma is 20 times more likely to kill. About 40% chose tornado.

Tornados make the news.

Representativeness heuristicRepresentativeness heuristic

How likely is it that X belongs to the class Y.

How similar is X to the prototype of Y.

People tend to neglect base rates and focus on characteristics.

Representativeness heuristicRepresentativeness heuristicConjunction fallacy

Linda

- 31 years, single, outspoken, bright

- philosophy, concerned with justice

- antinuclear demonstrations

Which is more probable?

A - Linda is a bank teller

B - Linda is bank teller and active in feminist movement

Many people chose B, because that fits with the feminist stereotype (or did?).

But, the probability of two events together cannot be higher than the probability of either.

Commitment heuristic Commitment heuristic (Lagnado & Shanks, 2003)(Lagnado & Shanks, 2003)

- More people read tabloids than broadsheets.

- The Reporter is the most popular newspaper.

- More progressives than liberals read the Reporter.

- More Liberals than Progressives read the others.

- Overall, 50% of readers are Liberals and 50% progressives.

Commitment heuristicCommitment heuristic- More people read tabloids than broadsheets.

- The Reporters is the most popular newspaper.




A reader is drawn randomly from the population.

How likely is it that the person is a Liberal?

People answer 50% (correct).







What newspaper would you guess the person reads?

Many people guess the Reporter (reasonable).

Now, what party does the person vote for?

People now judge the person with 80% certainty (instead of 50) to be a progressive!







What type of newspaper would you guess the person reads?

Many people guess Tabloid (reasonable).

Now, what party does the person vote for?

People now judge the person with 38% certainty (instead of 50) to be a progressive!

Commitment heuristicCommitment heuristicSo what?

- The amazing thing is that people change their estimates purely on the basis of no information.

- They just guess what type of paper, or what specific paper, the person reads. The person is drawn randomly.

- They then commit to the truth of this category and assign estimates of political voting thereafter.

- The estimates change (up or down) depending on category specificity (specific paper or type of paper) because the category structure is non-aligned.

Non-aligned categories

Brazil is the most likely country to win the World Cup.

At the same time, it is more likely that a European country will win than a South American country.

Commitment heuristicCommitment heuristicLagnado and Shanks (2003) study demonstrates that

simply asking about a category makes people use the information associated with that category, at that level.

It is an extreme form of base rate neglect, because the subjects are not given any misleading information. They are just asked a question without feedback.

Confirmation biasConfirmation bias

An additional source of induction errors is confirmation bias

- tendency to notice information that supports one´s beliefs.

Testing rules (Wason, 1960)

What rule do I have in mind with these 3 numbers?

2 4 6

Write down three numbers and I will say whether they follow the rule. Tell me when your are certain you have discovered the rule.

Most subjects tried numbers that followed their own hypothesis.

They key to discovering the rule is to generate numbers that would falsify one´s hypothesis.

Judgment and decision makingJudgment and decision making

Utility approach

- people are rational

- maximize expected utility

Problems- people do not always act rationally

- people have limited computational resources

- utility is ambiguous

- people focus on different aspects dependning on context

Focusing illusionFocusing illusion A -How happy are you?

B -How many dates did you have last month?

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

A then B B then A

Corr

ela

tion b

etw

een a

nsw

ers

Framing Framing (Tversky & Kahneman, 1981)(Tversky & Kahneman, 1981)

A disease is about to burst out. If nothing is done, 600 people will die. There are two programs for dealing with the situation. The estimates of the outcomes are as follows:

Program A

- 200 people will be saved.

Program B

- 1/3 probability that 600 people are saved, 2/3 probability that noboby will be saved.

72% chose A

FramingFraming

A disease is about to burst out. If nothing is done, 600 people will die. There are two programs for dealing with the situation. The estimates of the outcomes are as follows:

Program C

- 400 people will be killed.

Program D

- 1/3 probability that nobody will die, 2/3 probability that 600 people will die.

78% chose D

FramingFraming

The results are remarkable, since

Program A = Program C (same expected utility)

Program B = Program D (same expected utility)

Decision justificationDecision justification

Offer to buy a vacation package at low price.

Options:

- buy - don´t buy - pay 5 dollar fee to postpone decision 2 days

Pass group

- You just passed an exam

Fail group

- You just failed an exam

Indeterminate group

- You will find out about exam results in 2 days

0

10

20

30

40

50

60

70

Pass Fail Indeterminate

Pe

rce

nta

ge

of

pa

rtic

ipa

nts

Buy

Don´t buy

Wait

- Many chose ”wait” in the indeterminate group.

- But the pass and fail groups indicate that outcome doesn´t matter.

- People want some justification, before they make the decision that they will make anyway, no matter what the outcome is.

Reasoning, deciding, & the brainReasoning, deciding, & the brain

Prefrontal cortex (PFC)

- sensory information

- memory retrieval

- working memory

- planning

- coordination

- anticipation

- inhibition

- relational integration

- emotion/response integration



Perseveration

- task switching difficulty

PFC damage reduces performance in

- card sorting tasks, which require switching strategies

- tasks that require connecting different parts

- problem solving tasks generally

- Problem solving activates PFC in normal participants

- More complex problems activate larger areas of PFC.



Relational integration (Waltz et al., 1999)

Task 1

Easy: A is smaller than B, B is smaller than C

Hard: A is smaller than B, C is smaller than A

Task 2

Easy Medium Hard



Relational integration (Waltz et al., 1999)

Emotional decisions and the brainEmotional decisions and the brainPrefrontal cortex (PFC)

IOWA gambling task and somatic markers

- four decks of cards

- associated with different outcomes and probabilities

- participants chose cards from any deck for 100 trials

- for each choice they win money, or win and lose money

A B C D

Win every trial: 100 100 50 50Net result every 10 trials: -250 -250 +250 +250Status: BAD BAD GOOD GOOD

VMPFC patients go for the bad decks Control patients show higher SCR (high consistent wins, but higher variable losses also). response to the bad decks (A B)

Control patients learn to go for the good decks VMPFC patients do not. (lower consistent wins, but lower variable losses also).

Emotional decisions and the brainEmotional decisions and the brainPrefrontal cortex (PFC)

IOWA gambling task and somatic markers

- PFC is thought to integrate somatic markers, emotion-based bodily signals generated from the body, with different

response options

- PFC damage reduces task performance and somatic markers associated with different choices

A B C D

Win every trial: 100 100 50 50Net result every 10 trials: -250 -250 +250 +250Status: BAD BAD GOOD GOOD

Emotional decisions and the brainEmotional decisions and the brainUltimatum game

Partner: sometimes human, sometimes computer

Offers: 5/5, 7/3, 8/2, 9/1

Turn the offer down, and you get nothing

Emotional decisions and the brainEmotional decisions and the brainUltimatum game (Sanfey et al., 2003)

People sometimes reject the offer, when the offers are ”unfair”.

They do this to a larger extent if the partner is human.


Activation difference: [Human unfair] – [Human fair]


Anterior Insula

- Negative emotion, pain, distress, hunger, etc

Anterior Cingulate Cortex

- Cognitive conflict, error detection

Dorsolateral Prefrontal Cortex

- Goal maintenance, executive control


Activation for unfair offers

Emotional decisions and the brainEmotional decisions and the brainUltimatum game (Wout et al., 2006)

Skin conductance

Synthetic HappinessSynthetic Happiness

► Syntetisk lyckaSyntetisk lycka Är den lika verklig? Är den lika verklig?

Händelse i ert livHändelse i ert liv► Som har ökat lycka markantSom har ökat lycka markant► Minskat lyckat markantMinskat lyckat markant► Hur vet ni det? Hur vet ni det? ► Händelser som skulle öka/minska lyckar markant? Händelser som skulle öka/minska lyckar markant?

► Hur tolkar ni det han säger? Hur tolkar ni det han säger?

Date post:	02-Jan-2016
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Reasoning & Decision making

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