Cognitive Processes PSY 334

1. Cognitive ProcessesPSY 334 Chapter 10 – Reasoning & Decision-Making August 19, 2003

2. Incubation Effects • Some kinds of problems tend to benefit from interruption (incubation). • 55% without break, 64% 1 hr, 85% 4 hr. • Delay may disrupt set effects. • Problems depending on a set of steps or procedures do not benefit from interruption. • Subjects forget their plan and must review what was previously done.

3. Insight • There is no magical “aha” moment where everything falls into place, even though it feels that way. • People let go of poor ways of solving the problem during incubation. • Subjects do not know when they are close to a solution, so it seems like insight – but they were working all along.

4. Research on Logic • Logic – a subdiscipline of philosophy and mathematics that formally specifies what it means for an argument to be correct. • Human deviations from logic were thought to be malfunctions of the mind. • Recent comparisons of human thinking show that logic is not an appropriate prescriptive norm.

5. Two Kinds of Reasoning • Reasoning – the process of inferring new knowledge from what we already know. • Deductive reasoning – conclusions follow with certainty from their premises. • Reasoning from the general to the specific. • Inductive reasoning – conclusions are probable rather than certain. • Reasoning from the specific to the general. • Probabilistic – based on likelihoods.

6. Conditionals • If-then statements. • Antecedent – the “if” part. • Consequent – the “then” part. • Rules of inferences using conditionals: • Modus ponens -- If A then B, A, conclude B • Modus tollens – If A then B, not-B, conclude not-A • Notation: negation, implication, therefore.

7. Logical Fallacies • Denial of the antecedent: • If P then Q, not-P, conclude not-Q • If P then Q, not-P, conclude Q • Affirmation of the consequent: • If P then Q, Q, conclude P • If P then Q, Q, conclude not-P • Subjects seem to interpret the conditional as a biconditional – if means “if and only if”

8. How People Reason • People may be reasoning in terms of conditional probabilities. • Conditional probabilities can be found that correspond to acceptance rates for fallacies. • Wason selection task – can be explained in terms of probabilities. • Also explained by a permission schema

9. Quantifiers • Categorical syllogism – analyzes propositions with quantifiers “all,” “no,” and “some.” • Fallacies: • Some A’s are B’s • Some B’s are C’s • Conclude: Some A’s are C’s • Substitute women for A, lawyers for B, men for C to see what is wrong.

10. Atmosphere Hypothesis • People commit fallacies because they tend to accept conclusions with the same quantifiers as the premises. • No A’s are B’s • All B’s are C’s • Conclude No A’s are C’s. • The logical terms (some, all, no, not) create an atmosphere that predisposes acceptance of the same terms.

11. Two Forms • People tend to accept a positive conclusion to positive premises, negative conclusion to negative premises. • Mixed premises lead to negative conclusions. • People tend to accept universal conclusions from universal premises (all, no), particular conclusions from particular premises (some, some not).

12. Limitations • Atmosphere hypothesis describes what people do, but doesn’t explain why. • People violate predictions of the atmosphere hypothesis. • More likely to accept a syllogism if it contains a chain leading from A to C. • People should accept a syllogism with two negative premises, but correctly reject it.

13. Process Explanations • People construct a mental model to think concretely about the situation. • Correct conclusions depend upon choosing the correct mental model. • Errors occur because people overlook possible explanations of the premises: • All the squares are striped • Some striped objects have bold borders. • Some of the squares have bold borders.