Cognitive Processes PSY 334 Chapter 10 Reasoning DecisionMaking

Cognitive Processes PSY 334 Chapter 10 – Reasoning & Decision-Making August 19, 2003

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

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

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

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

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

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

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

Quantifiers o Categorical syllogism – analyzes propositions with quantifiers “all, ” “no, ” and “some. ” o Fallacies: n n 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.

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

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

Limitations o Atmosphere hypothesis describes what people do, but doesn’t explain why. o People violate predictions of the atmosphere hypothesis. n n 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.

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