Judgment under Uncertainty: Heuristics and Biases

Transcription

1 Judgment under Uncertainty: Heuristics and Biases Tversky, A., & Kahneman, D. (1974). Science, 185: Ching-Fan Sheu Sheu (NCKU) Heuristics & Biases 1 / 33

2 A. Tversky & D. Kahneman Sheu (NCKU) Heuristics & Biases 2 / 33

3 Summary People rely on heuristics to make judgments under uncertainty. Biases can occur with these heuristics. Cognitive illusions are like perceptual illusions. Three basic heuristics: 1 Representativeness 2 Availability 3 Anchoring and adjustment Sheu (NCKU) Heuristics & Biases 3 / 33

4 A couple of things about learning I forget what I hear; I remember what I see; I know what I do. Use it or lose it. Sheu (NCKU) Heuristics & Biases 4 / 33

5 Introduction Judgment Decision making Risk Uncertainty Sheu (NCKU) Heuristics & Biases 5 / 33

6 Historical background von Neumann, J., & Morgenstern (1944). Theory of games and economic behavior. Sheu (NCKU) Heuristics & Biases 6 / 33

7 Historical background Edwards, W. (1954). The Theory of Decision Making. Psychological Bulletin, 51, Peterson, C.R., & Beach, L.R. (1967). Man as Intuitive Statistician, Psychological Bulletin, 68(1), Simon, H.A. (1969). The Sciences of the Artificial. MIT Press. Sheu (NCKU) Heuristics & Biases 7 / 33

8 Bounded Rationality The human being striving for rationality and restricted within the limits of his knowledge has developed some working procedures that partially overcome these difficulties. These procedures consist in assuming that he can isolate from the rest of the world a closed system containing a limited number of variables and a limited range of consequences. Sheu (NCKU) Heuristics & Biases 8 / 33

9 Perceptual illusions Sheu (NCKU) Heuristics & Biases 9 / 33

10 Perceptual illusions Sheu (NCKU) Heuristics & Biases 10 / 33

11 Perceptual illusions Sheu (NCKU) Heuristics & Biases 11 / 33

12 Wason Selection Task (Wason, 1966) Each of these cards has a letter on one side and a number on the other. Which two cards should you turn over to allow you to decide if the following statement is true: If there is a D on one side, there is a 5 on the other? Sheu (NCKU) Heuristics & Biases 12 / 33

13 Mental short-cut Satisficing describes the decision maker taking the short cut of defining a set of aspirations and then settling on some (usually the first) alternative that meets the minimum requirements. Sheu (NCKU) Heuristics & Biases 13 / 33

14 Representativeness A B Pr{A} Pr{B} People judge probabilities based on how much something resembles another thing. Biases: Base rate neglect Insensitivity to sample size Misconceptions of chance Insensitivity to predictability The illusion of validity Regression fallacy Sheu (NCKU) Heuristics & Biases 14 / 33

15 Availability People judge the probability of an event by the ease with which occurrences can be brought to mind. Biases due to how easy the instances can be retrieved the effectiveness of search set easy or hard to imagine illusory correlation Sheu (NCKU) Heuristics & Biases 15 / 33

16 Anchoring and adjustment People make a final estimate by starting from a first guess and then adjust. Biases due to initial estimates insufficient adjustment Sheu (NCKU) Heuristics & Biases 16 / 33

17 Mark Stone was a graduate student at a state university in the Midwest. He was extremely bright, had good grades and excellent test scores, and had been in a number of graduate programs before, but never seemed to make much progress toward completing his doctorate. This year an applicant to the same graduate program had excellent grades and test scores, had previous graduate school background, was rejected by the admission committee because he looked too much like Mark Stone. Sheu (NCKU) Heuristics & Biases 17 / 33

18 A Geography Quiz Which of the following cities is to the north of the others? Keelung, Taipei, Tamsui, Hualien. Sheu (NCKU) Heuristics & Biases 18 / 33

19 In early October of 2001, a couple argued about the outcome of that year s World Series. Jane: The series would be decided in seven games with the Yankees losing the final game. Dave: The Yanks would lose the first two games on the road, won the next three games at home, and then lost the series by losing the last two games on the road again. Whose scenario was more believable before the series began? Sheu (NCKU) Heuristics & Biases 19 / 33

20 Lake Wobegon Effect In a survey of faculty at the University of Nebraska, 68% rated themselves in the top 25% for teaching ability (Cross, 1977). In a similar survey, 87% of MBA students at Stanford University rated their academic performance as above the median (Zuckerman, et al, 2001). Sheu (NCKU) Heuristics & Biases 20 / 33

21 Gambler s Fallacy Sheu (NCKU) Heuristics & Biases 21 / 33

22 The Illusion of Control (Langer, & Roth, 1975) Which way would you wage more money on a bet of a dice throw? You roll the dice or your opponent rolls the dice? You and a friend of yours bought a couple of lottery tickets. The machine picked the numbers of both of you. Would you exchange your ticket with your friend? Sheu (NCKU) Heuristics & Biases 22 / 33

23 In fall 1986 Columbia Records executives were very optimistic about sales of the Bruce Springsteen five-record boxed set priced at $40. Springsteen s last album, Born in the U.S.A., sold 13 million copies. A Columbia spokesmen says: We can imagine [the new album] selling just as well. Never underestimate the popularity of Springsteen. The boxed set did sell very well. But after Christmas of that year, the same boxed set could be bought for $10 because Columbia overproduced about one million boxes too many. Sheu (NCKU) Heuristics & Biases 23 / 33

24 My next-door neighbor at Tainan is a professor at NCKU. He likes to read poetry, is rather shy, and is small in stature. Is he is more likely to be a professor of engineering or of psychology? Sheu (NCKU) Heuristics & Biases 24 / 33

25 A psychoanalyst writes, In all those drug addicts I have seen or whose treatment I have supervised, the mother and father appear psychically removed from their children, from which the psychoanalyst concludes that a drug user is a person who when a child was deeply lonely and isolated. Sheu (NCKU) Heuristics & Biases 25 / 33

26 Seek, and ye shall find Sheu (NCKU) Heuristics & Biases 26 / 33

27 966 P.C. Austin et al. / Journal of Clinical Epidemiology 59 (2006) 964e969 Born under a bad sign (Austin, et al., 2006) Table 1 Diagnoses for which residents with given astrological sign had a higher probability of hospitalization compared to residents born under the remaining astrological signs combined: results from derivation cohort Astrological sign ICD-9 code Diagnosis P-value Relative risk Aries 733 Other disorders of bone and cartilage Intestinal infections due to other organisms Taurus 820 Fracture of neck of femur Diverticula of intestine Gemini 998 Other complications of procedures, NEC Alcohol dependence syndrome Cancer 560 Intestinal obstruction without mention of hernia Other and unspecified anemias Leo 578 Gastrointestinal hemorrhage V58 Encounter for other and unspecified procedure and aftercare Virgo 823 Fracture of tibia and fibula Excessive vomiting in pregnancy Libra 808 Fracture of pelvis Subarachnoid hemorrhage Scorpio 566 Abscess of anal and rectal region Lymphoid leukemia Sagittarius 784 Symptoms involving head and neck Fracture of humerus Capricorn 799 Other ill-defined and unknown causes or morbidity and mortality Abortion Aquarius 413 Angina pectoris Other bacterial pneumonia Pisces 428 Heart failure Other acute and subacute forms of ischemic heart disease Abbreviation: NEC = not elsewhere classified. compared to other residents of Ontario, with a relative risk number of potential associations. We began the study with of 1.15 (P ). Similarly, residents born under the no prespecified hypotheses. Rather, we searched sequen- Sheu (NCKU) Heuristics & Biases 27 / 33

28 A path is a line that connects an x in the top row of a structure to an x in the bottom row by passing through one and only one x in each row. In which of the two structures are there more path? Sheu (NCKU) Heuristics & Biases 28 / 33

29 Human Geography - Quiz 1 As of January 1, 2011, France had a population of 65,821,885. Estimate the size of population in South Africa. Sheu (NCKU) Heuristics & Biases 29 / 33

30 Human Geography - Quiz 2 As of May 2010, Indonesia had a population of 237,556,363. Estimate the size of population in South Africa. Sheu (NCKU) Heuristics & Biases 30 / 33

31 Hindsight Every great scientific truth goes through three stages. Fist people say it conflicts with the Bible. Next, they say it has been discovered before. Lastly, they say they have always believed it. Louis Agassiz, Sheu (NCKU) Heuristics & Biases 31 / 33

32 Wason Selection Task Revisited (Cosmides & Toby, 1992) Each of these cards has a description on one side and another on the other. Which two cards should you turn over to allow you to decide if the following statement is true: If a person is drinking beer, then that person must be 18 years of age? Sheu (NCKU) Heuristics & Biases 32 / 33

33 Concluding remark Whenever there is a simple error that most laymen fall for, there is always a slightly more sophisticated version of the same problem that experts fall for. Amos Tversky, Sheu (NCKU) Heuristics & Biases 33 / 33