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# Cog5 lecppt chapter11

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• Green is accurate reasoning. Red is inaccurate reasoning.
Feedback: We are more likely to read about motor-vehicle deaths or see them on the evening news and thus judge them as being more likely.
Feedback: Illusory covariations would have us detect a relationship that is not there and hence lead to prejudice.
Feedback: We make a lot of judgment errors when thinking about covariation. Hence, we are not good at it.
Feedback: Illusory correlations are pervasive even when people have vast experience in a domain.
Feedback: Heuristics are fast and efficient; reason-based choices are slower.
Feedback: People used heuristics to make judgments even when given information that clearly showed they were wrong.
Feedback: The matching strategy refers to wording.
• ### Cog5 lecppt chapter11

1. 1. © 2010 by W. W. Norton & Co., Inc. Judgment and Reasoning Chapter 11 Lecture Outline
2. 2. Chapter 12: Judgment and Reasoning  Lecture Outline  Judgment Heuristics  Anchoring  Detecting Covariation  Assessing the Damage  Confirmation and Disconfirmation  Logic  Decision Making
3. 3. Judgment Heuristics  Induction （歸納） is a pattern of reasoning in which one seeks to draw general claims from specific bits of evidence  Based on what you know about Allen, what is likely to cheer him up today?  Based on what you know about cars, what is the best kind to buy?
4. 4. Judgment Heuristics  Heuristic （捷思）  Reasonably efficient and accurate  Gain efficiency lose accuracy  Judgment heuristics include  Attribute substitution  Availability heuristic  Representativeness heuristic
5. 5. Judgment Heuristics  Attribute substitution is a strategy used when we do not have easy access to a desired piece of information  Instead, we base our decision on readily available information (a proxy or index) that we believe is correlated with the desired information
6. 6. Judgment Heuristics  Ease of reading = author intelligence
7. 7. Judgment Heuristics  Availability heuristic  Specific case of attribute substitution  Ease with which examples come to mind is an index of frequency or likelihood  This class is easy—I know four people who got A’s.
8. 8. Judgment Heuristics  For instance, consider  In the English language, are there more words that start with the letter “R” or with the letter “R” in the third position?  Who washes the dishes more often, you or your roommates?  Are more deaths caused by crimes or by diseases?
9. 9. Judgment Heuristics  The availability heuristic  More words that begin with “R”  Reality  More words with “R” in the third position,  But words that begin with “R” are easier to bring to mind
10. 10. Judgment Heuristics  The availability heuristic may lead us to believe that we always do the housework ourselves
11. 11. Judgment Heuristics  The availability heuristic may lead us to think that more deaths are caused by crimes or accidents than by disease  In reality, far more deaths are caused by disease
12. 12. Judgment Heuristics  Availability heuristic  Group of students asked to recall past episodes in which they had been assertive (Schwarz et al., 1991)  One group gave 6 examples, and another, 12 examples  Which group then judged themselves to be more assertive in general?
13. 13. Judgment Heuristics  Those that gave 6 examples judged themselves as more assertive  Easier to come up with 6 examples
14. 14. Judgment Heuristics  The representativeness heuristic is another example of attribute substitution Member Prototype Category resembles resembles
15. 15. Judgment Heuristics  For instance, consider  Do you assume anything about someone if you discover that he or she is a lawyer or an engineer?  If a coin toss results in “heads” six times in a row, what are the odds of getting “tails” the seventh time?  If you hear an anecdote about a marathon runner who has smoked for decades and is perfectly healthy, does this mean that smoking is safe?
16. 16. Judgment Heuristics  The representativeness heuristic  All lawyers or all engineers are homogeneous (a stereotype)  We assume that each individual member of a category has the traits we associate with the category overall.
17. 17. Judgment Heuristics  The representativeness heuristic  The seventh coin toss is more likely to be tails (the gambler’s fallacy), but the odds are still 50-50
18. 18. Judgment Heuristics  The representativeness heuristic  Smoking must be okay for your health based on one example (anecdotal evidence or “man who” stories)  This is an example of reasoning from one instance to the population.
19. 19. Judgment Heuristics  Representativeness heuristic  Watched “prison guard” discussing his job (Hamill et al., 1980)  One variable of the study was whether the guard was compassionate or contemptuous. Another variable was whether the participants were told the guard was representative of all guards.  What did participants later conclude about prison guards in general?
20. 20. Judgment Heuristics Compassionate Contemptuous Representative Compassionate Contemptuous Not Representative Compassionate Contemptuous Judgments were based on characteristics independent of whether participants were told the guard was representative or not
21. 21. Detecting Covariation  Covariation  Relationship between two variables  Negative or positive and can vary in strength.  Does college education lead to a higher paying job?  Do you feel better when you have a good breakfast?
22. 22. Detecting Covariation  An illusory covariation  A perceived pattern such that one variable predicts another  A study of Rorschach inkblots found that even when fictitious patients and fictitious responses were randomly paired, people believed they had found patterns.  Other studies have found that clinicians believed that homosexuals and heterosexuals interpreted these images differently even though the data did not show this.
23. 23. Detecting Covariation  Confirmation bias  More responsive to evidence that confirms one’s beliefs  Similar to overregularization by schemata  Essentially we ignore disconfirming data
24. 24. Detecting Covariation  Big dogs are vicious  Notice examples that fit this pattern more readily (biased attention)  Will recall examples that fit the pattern more readily (biased memory)
25. 25. Detecting Covariation  Another reason that estimates of covariation can be inaccurate is a neglect of base-rate information.  Base-rate information—information about the likelihood of an event  Diagnostic information—does an individual case belong to a category?
26. 26. Detecting Covariation  Consider this example  Testing a new drug, in hopes that it will cure hepatitis  Does taking the drug covary with a better medical outcome?
27. 27. Detecting Covariation  Results  70% of the patients taking the drug do recover from the illness  Uninterpretable  If it turns out that the overall recovery rate is 70%, then our new drug is having no effect whatsoever.
28. 28. Detecting Covariation  Interpretation  We need to know the base rate  How many are cured with no treatment  How many more are cured with treatment
29. 29. Detecting Covariation  Kahneman and Tversky (1973)  Base-rate information: 70 lawyers and 30 engineers  Diagnostic information (engineering): “likes carpentry, sailing, math puzzles; dislikes politics”
30. 30. Detecting Covariation  The base-rate with no diagnostic information = base rate  The base rate is not neglected!  Base-rate and diagnostic information = diagnostic information.  The base rate is neglected!
31. 31. Detecting Covariation Is Tom an engineer? Does Tom resemble an engineer? Representativeness heuristicWhat percentage are engineers? Attend to base rate Base-rate neglect
32. 32. Assessing the Damage  Imagine your friend has a system for playing the lottery  What if she tells you it only worked the last time she played or  She tells you it worked the last ten times she played  Which do you believe?  Data set size and drawing conclusions about a new category: One time might be lucky; ten times is likely to be true.
33. 33. Assessing the Damage  Dual-process models  System 1 refers to thinking that is fast, automatic, and uses heuristics  System 2 refers to thinking that is slower, effortful, and more likely to be correct
34. 34. Assessing the Damage  Whether System 1 or System 2 is used depends on the context of the decision  How much time is available for the decision?  How much attention and working memory are available?  And how the problem is presented  What format are the data in?  Are statistical concepts primed?
35. 35. Assessing the Damage  Emphasizing chance cues statistical reasoning  A story about a restaurant assessment based on a single meal chosen by one person  Informed assessment?  Now imagine that the person dropped his or her pencil on the menu to pick that meal  Informed assessment?
36. 36. Assessing the Damage  Background knowledge increases the likelihood that participants will pay attention to base rates  For instance, when predicting whether a particular student will pass an exam, participants do pay attention to the base-rate information that only 30% of students pass the exam
37. 37. Assessing the Damage 37
38. 38. Assessing the Damage  Training can influence the likelihood of reasoning with System 2  For instance, participants can be trained that large samples of data are more reliable than small samples  Taking a statistics class also improves reasoning when sample size is important
39. 39. Confirmation and Disconfirmation  Deduction start with general premises and ask what follows  If you believe that red wine gives you headaches, what follows from this?  If relationships based on physical attraction never last, what follows from this?
40. 40. Confirmation and Disconfirmation  Rooster wants to prove his crowing causes the sun to rise  Confirming evidence: every day the rooster crows, and the sun rises  Disconfirming evidence: one day he must not crow and see what happens
41. 41. Confirmation and Disconfirmation  Confirmation bias—more responsive to evidence that confirms one’s beliefs and less responsive to evidence that challenges one’s beliefs
42. 42. Confirmation and Disconfirmation  In a classic demonstration of confirmation bias, Wason (1966) presented sequences like “2-4-6”  Several minutes to figure out rule (ascending numbers two apart)  They only sought confirming evidence  Did not seek disconfirming evidence  A few did discover the rule  Sought disconfirming evidence
43. 43. Confirmation and Disconfirmation  Selective Memory.  Gamblers betting on a football game  Wins are confirming evidence  Losses are remembered as near-wins
44. 44. Confirmation and Disconfirmation  Belief perseverance is a tendency to continue endorsing a belief even when evidence has completely undermined it
45. 45. Confirmation and Disconfirmation  Assigned to good or bad groups  Told about assignment Bad judgers Good judgers Ability to judge whether authentic Bad Good Self-ratings of social sensitivity Low High
46. 46. Logic  Categorical syllogisms logical arguments containing two premises and a conclusion  Syllogisms （三段論 ） can be valid or invalid
47. 47. Logic  Is this syllogism valid?  All P are M.  All S are M.  Therefore, all S are P.  In concrete terms:  All plumbers 水電工 are mortal 凡人 .  All sadists 虐待狂 are mortal.  Therefore, all sadists are plumbers.
48. 48. Logic  The errors people make on syllogisms tend to fall into predictable categories  One pattern is belief bias—if the syllogism’s conclusion is something people already believe to be true, they are more likely to judge the conclusion as following from the premises
49. 49. Logic  Low-level matching strategy between the words in the premises and those in the conclusions (the atmosphere effect)  Some A are not X.  Some B are not X.  Therefore, some A are not B. (invalid)
50. 50. Logic  A conditional statement  If X, then Y.  If antecedent, then consequent
51. 51. Logic  modus ponens, affirming the antecedent  If P is true, then Q is true.  P is true.  Therefore, Q must be true.  Easiest form of logic
52. 52. Logic  modus tollens, denying the consequent  If P is true, then Q is true.  Q is false.  Therefore, P must be false.  More difficult
53. 53. Logic  Two common errors are affirming the consequent  If P is true, then Q is true.  Q is true.  Therefore, P must be true. (invalid)  And denying the antecedent  If P is true, then Q is true.  P is false.  Therefore, Q must be false. (invalid)
54. 54. Logic  If P is true, then Q is true. P true P no true Q true Modus ponens Illogical Q not true Illogical Denial of the consequent
55. 55. Logic  If P is true, then Q is true. Conditional statement Type of reasoning P true, Q true Modus ponens P not true, Q not true Denial of the antecedent Q true, P true Affirmation of the consequent Q not true, P not true Modus tollens
56. 56. Logic
57. 57. Logic  For both syllogisms and conditional statements, errors are more likely when  Negatives are involved  The terms are abstract (e.g., letters) and not concrete
58. 58. Logic  Wason’s four-card task  “If a card has a vowel on one side, then it must have an even number on the other side”  Which cards must be turned over to test this rule?
59. 59. Logic 4% of people
60. 60. Logic A more concrete example “If a person is drinking beer, then the person must be over 19 years of age.”
61. 61. Logic 73% of participants
62. 62. Logic  Why are some versions of the four-card problem difficult and others easy?  Evolutionary psychologists suggest people can “detect cheaters” who are not following rules of social interaction
63. 63. Logic  Alternatively, a pragmatic reasoning schema may help explain the ease  These schemas involve “permission” or “cause and effect” relations
64. 64. Logic  Problem: “If a form says ‘entering’ on one side, then the other side must include ‘cholera.’”
65. 65. Logic  Permission schema  “If a passenger wishes to enter the country, he or she must first receive a cholera inoculation.”
66. 66. Logic  Necessary condition  “If Jacob passed his driver’s test, then it’s legal for him to drive.”  Sufficient condition  “If Solomon is eligible for jury duty, then he is over 21.”
67. 67. Logic  Summary of logic  People commonly rely on reasoning strategies that are different from the principles of formal logic  Some of these principles are simple, such as the “matching strategy”  Others are more sophisticated, such as a “permission schema,” but may only be triggered under the right circumstances
68. 68. Decision Making  UtilityTheory  Expected value = (probability of a particular outcome) x (utility of the outcome)
69. 69. Decision Making  Many of our decisions follow the principle of utility maximization, or choosing the option with the greatest expected value
70. 70. Decision Making  However, many decisions do not follow this principle  For instance, consider the following problem, as framed either in terms of lives saved or lives lost
71. 71. Decision Making
72. 72. Decision Making  Framing changes the choices  Program A if the problem is “positively framed” in terms of lives saved  Program B if the problem is “negatively framed” in terms of lives lost  Identical utility
73. 73. Decision Making
74. 74. Decision Making Risk-seeking Risk-averse
75. 75. Decision Making To which parent would you award full child custody?
76. 76. Decision Making To which parent would you deny full child custody?
77. 77. Decision Making  An alternative view is known as reason- based choice, the idea that people make a decision only when they detect what they believe to be a persuasive reason for making that choice
78. 78. Decision Making
79. 79. Decision Making  Reason-based choice  Scenario A—there is only one choice (the Sony)  Scenario B—there are two choices
80. 80. Decision Making 80 Number of choices increases the sure choice
81. 81. Decision Making  The orbitofrontal cortex is essential for evaluation of somatic markers  Patients with damage will make risky decisions
82. 82. Decision Making  Emotions play a role in decision making, through what might be called affective heuristics  For instance, decisions that involve assessing risk may depend on the feeling of dread of an undesirable outcome, or anticipating the feeling of regret for having made the wrong choice  Note that the latter involves predictions about our future emotions, which are not necessarily accurate
83. 83. Decision Making People overestimate their future feelings 83
84. 84. Decision Making  Decision making and happiness  Unable to forecast our future feelings  Would be better off having others make our choices  We end up “stumbling on happiness”  We end up stressed by the “paradox of choice”
85. 85. Chapter 11 Questions
86. 86. 1. The fact that people report motor-vehicle deaths as more common than diabetes and homicides as more common than stomach cancer reflects which of the heuristics? a) simulation heuristic b) anchoring heuristic c) availability heuristic d) representativeness heuristic
87. 87. 2. Which of the following is TRUE of covariation? a) A negative covariation indicates that there is no relationship between two variables. b) People tend to underestimate covariation when they have theories about the relationship between two variables. c) Covariations are “all-or-none” and cannot vary in strength. d) Illusory covariations sometimes generate prejudice toward groups of people.
88. 88. 3. Which of the following is FALSE regarding confirmation bias? a) It works to bring our recollections into line with our expectations. b) It makes people more alert and responsive to evidence that confirms their beliefs than to challenging evidence. c) Its effects are usually offset by our general ability to think about covariation. d) It makes us unlikely to seek counterexamples.
89. 89. 4. Poor diagnostic reasoning and illusory correlations have been documented in all of the following cases EXCEPT a) individuals with considerable experience in the domain being judged. b) participants who have been offered cash bonuses for accurate performance. c) individuals for whom the stakes are very high (e.g., doctors and financial advisors). d) All of the above individuals demonstrate these errors.
90. 90. 5. According to the dual-process model of reasoning, one mode of thought is ___, while the other mode of thought is ___. a) association driven; speedy b) automatic; effortful c) slower; effortful d) automatic; effortless
91. 91. 6. In the study in which people were asked to judge their social sensitivity after being given false- positive or negative feedback (but then debriefed), participants were clearly influenced by a) views they had of themselves before the experiment. b) the feedback they had been given, even though they knew it was false. c) the feedback they had been given, but only if they had forgotten the debriefing that undermined this feedback. d) a memory search done after debriefing to help them disconfirm the false feedback.
92. 92. 7. In the context of a syllogism, what is a matching strategy? a) If the two premises match each other, the conclusion is accepted. b) If the conclusion matches the premises in wording and structure, it is accepted. c) Statements with the same structure are all seen as identical. d) People accept syllogisms when the conclusions match their beliefs.