Thinking: Reasoning Reasoning: manipulating internal representations to arrive at new knowledge or to draw new conclusions. Syllogistic reasoning: based on ‘accepted’ premises upon which conclusions are drawn. Task it to decide if conclusions are valid or not Valid conclusion: must be only conclusion possible based on relationships described in premises. Must be necessitated by premises, not just possible based on premises

Syllogistic reasoning Premise: statement assumed to be true for sake of argument, not necessarily empirically true Premise: All boys are athletes Premise also usually expresses a relationship between certain concepts, so boys are related to athletes in that all boys are a member of the category athletes.

Syllogistic reasoning Conclusion: to be valid must be necessitated by the premises. Must be only possible conclusion drawn base on relationships expressed in premises. Conclusion: a valid conclusion cannot just be reasonable or plausible based on premises, it must be necessary.

Venn or Euler diagrams for solving syllogisms Valid conclusion: all doctors are greedy

Syllogistic reasoning P1: All boys are athletes P2: All athletes are muscular C: All boys are muscular Valid: Use Venn Diagrams to determine.

Syllogistic reasoning P1: All boys are athletes P2: All muscular people are athletes C: All boys are muscular people Valid? See website for more reasoning problems

©John Wiley & Sons, Inc Huffman: Psychology in Action (8e) Conditional reasoning If: antecedent condition Then: consequent When the antecedent condition is met, the consequent will occur (no question about it!) Observation – what condition is actually present Conclusion: (valid or not valid)

©John Wiley & Sons, Inc Huffman: Psychology in Action (8e) Conditional reasoning If she has red hair Then she buys new shoes Observation: she has red hair (affirming antecedent) Conclusion: she buys new shoes (valid?)

©John Wiley & Sons, Inc Huffman: Psychology in Action (8e) If she has red hair Then she buys new shoes Observation: she has not red hair (denying the antecedent) Conclusion: she buys not new shoes (valid?)

©John Wiley & Sons, Inc Huffman: Psychology in Action (8e) If she has red hair Then she buys new shoes Observation: she buys new shoes (affirming the consequent) Conclusion: she has red hair (valid?)

©John Wiley & Sons, Inc Huffman: Psychology in Action (8e) If she has red hair Then she buys new shoes Observation: she buys not new shoes (denying the consequent) Conclusion: she has not red hair (valid) More problems on my website

Conditional Reasoning: Summary

©John Wiley & Sons, Inc Huffman: Psychology in Action (8e) Wason Selection Task Rule: if there is vowel on one side then there is an even number on the other side of the card

©John Wiley & Sons, Inc Huffman: Psychology in Action (8e) Abstract reasoning vs. Social contracts reasoning

Decision Making Physical differences vs. Symbolic differences Physical differences: JND or difference threshold – minimum physical difference necessary for detection Distance effect: the farther the comparison departs from the JND the faster or easier the discrimination Symbolic distance effect: decisions are faster, easier as symbols depart farther from each other. Rts for judging greater value decrease as difference between numbers increases for all age subjects

Decision Making Semantic congruity effect: faster decisions when decisions “make sense” with relevant semantics dimensions involved Faster response time for congruent on left and slowed response times for both conditions above.

Decision Making Plausible reasoning and distortions of geographic knowledge (ex: which is farther west San Diego, CA or Reno, NV?)

Algorithms and Heuristics Algorithm: step by step procedure guaranteed to provide a solution. Usually only applicable to very narrow, well-defined problems Ex: mathematical formulas, recipes Heuristics: less certain, but more generally applicable problem-solving methods Ex: football: control line of scrimmage, avoid turnovers; chess: control center of board; life: get an education, stay out of jail.

Types of Heuristics

Anchoring bias

Base rate bias Prof Smith has dark hair, black-rimmed glasses and reads poetry. 100% of Philosophers look this way, only 1% of Engineers do. Is it more likely that Smith is an philosopher or engineer?

Naïve Physics Misunderstanding of motion Mental models drawn from experience sometimes don’t correspond to the reality of the physical world.