Deduction
• biases and content effects
• bias = whenever there is a systematic deviation in performance from the normative approach
Belief Bias
• make conclusions based on personal beliefs about the world (you are supposed to use logical rules to draw conclusions)
• Selma Hayek looks best sporting the “uni-brow” that she had in “Frida”
• Ben Affleck and Jennifer Lopez will have a longlasting marriage
Validity of the silly statement
• sometimes being logical, means providing reasons for your conclusions
• Women look their best when sporting a “unibrow”
• The actress that played “Frida” sported a unibrow
• Selma Hayek is the actress that played “Frida”
• Selma Hayek looked best sporting the “unibrow” that she had in “Frida”
Laboratory evidence
• Believable conclusions = are consistent with your personal beliefs
• Unbelievable conclusions = are inconsistent with your personal beliefs (e.g., unibrow statement)
• also, valid and invalid conclusions
• believable/valid, believable/invalid, unbelievable/valid, unbelievable/invalid
Results
• Evans, Newstead, & Byrne (1993)• % of conclusions accepted as valid
• Valid Invalid• Believable 86% 66%• Unbelievable 62% 13%
• conclusion: the believability of a statement has a strong influence on people’s critical thinking (i.e., belief-bias effect)
content effects
• def.: whenever the “content” (i.e., the specific words) influences your critical thinking performance
• normative approach content is irrelevant and should not influence your performance
Wason selection task
• Manchester Leeds Train Car
• (imagine that these are four cards, each having a city on one side and a mode of transportation on the other)
• “Every time I go to Manchester I travel by train”
• answer: turn over Manchester and Car
results in laboratory
• Wason & Shapiro (1971)
• showed that students did a good job with this version of the task compared to an abstract version
• conclusion adding realistic words (content) to an abstract problem improved performance (thus, it’s a content effect)
guaranteed solution to the selection task (algorithm)
• D B 3 5 7• If a card has a D on one side, then it has a
3 on the other side.• answer: D, 5, 7
• p not p q not q not q• If p, then q• answer: p, not q
Test 1 Study Guide
• normative approach, descriptive approach• logic, def. of rational• logic vs. real-life• syllogisms, deduction, parts of the
syllogism, validity of conclusion, algorithm, Euler’s circles
• conditional reasoning problems, conditional, content of a problem vs. logical structure
Test 1 (cont.)
• logical rules related to conditional reasoning, affirming the antecedent, etc. (including modus ponens, modus tollens)
• Wason selection task, abstract vs. realistic content of a problem
• logical operators, if…then, and, or, not; two types of “or” (exclusive, inclusive)
• disjunctive reasoning; deontic content or deontic reasoning
Test 1 (cont.)
• bias, belief-bias, personal beliefs vs. logic, content effects
Top Related