Inductive reasoning

What is inductive reasoning

Forming generalisations (that aren’t certain) from examples or samples

What is hypothesis testing

Confirmation or dis confirmation of hypothesis

What is deductive reasoning

Reasoning to a conclusion from a set of statements where the conclusions follows the assumption that the statement is true

Hypothesis testing strategies

• Confirmation, search for evidence which verifies the hypothesis

• Falsification, search for evidence which disconfirms the hypothesis

Describe Wason’s 2-4-6 task (1960)

• Most participants show confirmation bias

• Only 21% correct with the first triple

• Asks participants to identify the rule and hypothesis for 2-4-6 to test the hypothesis on other numbers

• 28% never discovered the rule

What is confirmation bias

The tendency to interpret new evidence as confirmation of one’s existing beliefs or theories

Generation vs testing, 2-4-6 task

• People try to preserve information in the original triple (Cherubini et al 2005)

• In group 1 participants are given examples 2-4-6 and 16-18-20

• 30% success rate

• Group 2, participants given examples 6-8-10 and 9-14-15 (numbers aren’t going up in twos)

• 70% success rate

• Proves people will stick to the original sequence due to the role of prior knowledge

Klayman and Ha, 1987

• Claimed that the way in which the way Wason talked about falsification and the 2,4,6 task wasn’t appropriate and calling it ‘confirmation bias’ sounds negative

• Concluded that a positive test strategy is not always inappropriate and should be called this as opposed to confirmation bias

• Positive test strategy can also lead to conclusive falsification if the circumstances are right

Examples of hypothesis testing outside a lab

• Hypothesis, insomnia is caused by caffeine

• The positive test strategy is to remove the caffeine and see if it solves the insomnia

• Positive testing Is not irrational but an economical and diagnostic strategy of information search in many circumstances

Why do we use abstract tasks to investigate reasoning

• Control by removing extraneous variables and background knowledge

• All participants have exactly the same information

• Easier to manipulate aspects of the task

How can we enhance performance on the 2,4,6 task

• (Cowley and Byrne, 2005)

• Had two versions of the task, her version and Wason’s version and she told participants that Wason’s hypothesis is numbers ascending in twos or even numbers

• When participants were asked to test other people’s hypothesis, 62% abandoned the other person’s hypothesis (Wason’s) compared to 25% who abandoned their own

What is a positive test strategy

The tendency to ask questions in which a yes answer would tend to confirm the hypothesis being tested.