Reasoning

Question 1

What is deductive reasoning?

Answer 1

• Starting with some sort of premises, then you deduce a conclusion
• Determining the conclusions that must follow given that certain statements are true
• Premise 1: All planets are made of cheese
• Premise 2: Earth is a planet
• Conclusion: Earth is made of cheese

Question 2

-If it is raining, then Fred’s hair gets wet.
-It is raining.
-Fred’s hair gets wet.
HOW MANY PEOPLE (%) AGREED THIS WAS A VALID INFERENCE?

Answer 2

-98% agreed this was a valid inference (Marcus & Rips, 1979)

Question 3

-If it is raining, then Fred’s hair gets wet.
-Fred’s hair does not get wet.
-It is not raining.
HOW MANY PEOPLE (%) AGREED THIS WAS A VALID INFERENCE?

Answer 3

• 52% agreed this was a valid inference (Marcus & Rips, 1979)
• Need to go off what the first premise says

Question 4

-If it is raining, then Fred’s hair gets wet.
-Fred’s hair gets wet.
-It is raining.
HOW MANY PEOPLE (%) AGREED THIS WAS A VALID INFERENCE?

Answer 4

-33% agreed this was a valid inference (Marcus & Rips, 1979)

Question 5

-If it is raining, then Fred’s hair gets wet.
-It is not raining.
-Fred’s hair does not get wet.
HOW MANY PEOPLE (%) AGREED THIS WAS A VALID INFEFENCE?

Answer 5

-21% agreed this was a valid inference (Marcus & Rips, 1979)

Question 6

Why do people make mistakes?

Answer 6

• People can reason logically, but often fail to understand formal, logical tasks (e.g. Braine, 1978). E.g. not tasks they’re used to
• People do not reason logically (e.g. Woodworth & Sells, 1935)
• We should not expect people to reason in line with formal logic (e.g. Oaksford & Chater, 1994). Argued that it is not the right type of test, not evolved to think this way

Question 7

What are the Theories of deductive reasoning?

Answer 7

• Abstract-rule theories
• Mental models
• Dual systems approach
• Probabilistic approach

Question 8

What is the Abstract rule theory?

Answer 8

-Braine (1978)
-People reason logically but make mistakes:
– if they misunderstand the task
– if the required reasoning places too many demands on working memory
-Limited capacity to make sense of the task, can’t store and process

Question 9

What can improve reasoning performance? (Abstract rule theory)

Answer 9

• Performance can be improved by presenting additional clarifying sentences (to reduce comprehension errors, e.g. Braine et al., 1984)
• However, such additional information can also impair performance on some tasks (e.g. Byrne, 1989)

Question 10

What is the Mental model theory?

Answer 10

• Johnson-Laird (e.g. 1999)
• Everyday comprehension processes (mental models) are used on reasoning problems
• People create mental models to represent premises
• Reasoning involves examination of mental model and/or attempts to create alternative models

Question 11

What is principle of truth?

Answer 11

• Conclusions are drawn based on the initial model. People then try to falsify that conclusion by constructing alternative models
• The creation of alternative models is very demanding on working memory.
• THEREFORE “individuals … tend to construct mental models to represent explicitly only what is true…” (principle of truth) Johnson-Laird (1999)

Question 12

What did Newstead et al (1999) look into?

Answer 12

• Mental models theory predicts that people will consider more conclusions in problems where they must create more mental models
• Gave tasks permitting one or several mental models
• No difference in number of conclusions considered

Question 13

What is the Dual systems approach?

Answer 13

-Reviewed by Evans (2003)
-Reasoning involves two systems
-Fast, automatic, based on prior knowledge, belief and heuristics (rules of fun, e.g. shortcuts)
– Slow, deliberate, abstract, based on logic

Question 14

What did -Oaksford and Chater (e.g. 2001) find about probabilistic reasoning?

Answer 14

-People use ‘probabilistic reasoning’ rather than logic to solve deductive reasoning tasks

Question 15

What are Thematic materials?

Answer 15

• Perhaps people are better at reasoning when the material is meaningful?
• BUT correct answer does not necessarily imply correct reasoning
• Memory cuing hypothesis (Griggs & Cox, 1982)
• Good memory, not meaning you are good at reasoning

Question 16

What is Social contract theory?

Answer 16

• We have strategies for detecting cheats who receive benefits without incurring the appropriate costs.
• We should be particularly good at versions of the Wason task that involve social contracts.
• Cosmides & Tooby (1989)

Question 17

What did Gigerennzer and Hug (1992) find about pensions?

Answer 17

• ‘If an employee gets a pension (P) then s/he has worked for 10 years (Q)’
• Who is violating the rule?
• Pension P
• No Pension not-P
• Worked 10 years Q
• Worked 8 years not-Q
• Imagine you are the employer OR imagine you are the employee

Question 18

Problems for social contract theory

Answer 18

• Some facilitatory contexts do not involve costs and benefits that are socially exchanged – BUT these have not always replicated
• Only applies to ‘deontic versions of the Wason task (‘if you do X you must do Y’) and not to ‘indicative’ versions (‘if there is a P then there is a Q’)

Question 19

What did Oaksford and Chater (1994) find about selection tasks?

Answer 19

• Selection task is not deductive, but a matter of ‘optimal data selection’
• Confirming instances may be useful, as well as counterexamples
• What matters is the expected reduction in uncertainty concerning whether rule is true or false. According to this measure: P > Q > not-Q > not-P
• Meta analysis of over 30 experiments using different versions of the selection task
• 89% choose A P
• 62% choose 4 Q
• 25% choose 7 NOT Q
• 16% choose D NOT P

Question 20

Deductive reasoning: summary

Answer 20

-People make characteristic errors in deductive reasoning
-These are attributed to:
– Failure to understand the task
– Lack of logical approach
– Tendency towards probabilistic approach in line with real-life reasoning

Question 21

What is Inductive reasoning?

Answer 21

• Going beyond the information provided to draw generalised conclusions – Hypothesis testing
• Note that conclusions may not always be true

Question 22

What were the results of the Wason 2-4-6 task?

Answer 22

• Only 21% correct with first statement of rule (but over 70% correct in the end)
• Tendency to attempt to confirm (rather than disconfirm) original hypothesis
• 1960

Question 23

What did Tweney et al (1980) find when looking at performance?

Answer 23

-Performance does not improve when specifically instructed to use a disconfirmatory approach

Question 24

What did Mynatt et al (1977) look at when Firing particles?

Answer 24

• Select direction in which to fire particle across the screen
• Then choose one of a pair of possible screens on which to test hypothesis (by firing additional particles)
• Confirmation, disconfirmation & control groups

Question 25

What did Mynatt et al (1977) find?

Answer 25

• Percentages of people choosing ‘confirm’ screen:
• Confirm group: 71%
• Disconfirm group: 70%
• Control: 71%
• People consistently chose screens that would allow them to confirm their hypotheses
• But 91% of participants changed to a correct hypothesis when given disconfirmatory evidence

Question 26

What did Mitroff (1974) find when looking at NASA scientists?

Answer 26

• Majority of NASA scientists (N = 40) interviewed were highly committed to confirming their own theoretical positions
• They argued that without it, many good, new, but undeveloped ideas would die as a result of premature falsification
• The scientists who held such views were rated as especially prominent and successful by their peers

Question 27

Are we rational?

Answer 27

• What’s the norm?
• Do we expect people to reason in line with formal logic?
• Or might we decide that reasoning is ‘rational’ if it is optimally adapted to the environment (e.g. ‘adaptive rationality’ proposed by Anderson, 1990)

Question 28

Summary

Answer 28

• People often make ‘errors’ in deductive and inductive reasoning
• This may be because laboratory tasks are often highly contrived and hard to relate to real-life situations
• Often the way people behave makes sense for real-life reasoning