Cognitive Processes PSY 334

1. Cognitive ProcessesPSY 334 Chapter 10 – Reasoning & Decision-Making May 28, 2003

2. Set Effects • Set effect – when previous experience biases a subject toward a particular operator. • Can prevent finding the solution to a new problem. • Luchins water jug problem. • Addition solution: 2A + C • Subtraction solution: B – A – 2C • New addition problems solved quicker and subtraction problems solved more slowly.

3. Einstellung Effect • Mechanization of thought – a set effect in which subjects get used to using a particular solution strategy. • After using B – 2C – A, subjects cannot find the easier solution A – C to problem 8. • 64% of whole setup group failed 8 & 79% used less efficient solution to 9 & 10. • 1 % of controls used B-2C-A & 95% solved question 8;

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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”

10. 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

11. 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.

12. 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. • Universal premises go with universal conclusions, particular with particular. • Does not fully explain behavior.

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.