Presentation on theme: "Psychology of decision making"— Presentation transcript:
1 Psychology of decision making Classical theories, Nov 5, 2011
2 Dollar auction Shubick 1971 1. The dollar bill will be sold to the highest bidder.2. The second highest bidder must also pay his or her bid, but receives nothing.3. Students may not collude during the auction.4. The minimum increment for a new bid is $1
3 Bernoulli and expected utility In the presence of risky outcomes, a decision maker could use the expected value criterion as a rule of choice: higher expected value investments are simply the preferred ones.For example, suppose there is a gamble in which the probability of getting a $100 payment is 1 in 80 and the alternative, and far more likely, outcome, is getting nothing. Then the expected value of this gamble is $1.25. Given the choice between this gamble and a guaranteed payment of $1, by this simple expected value theory people would choose the $100-or-nothing gamble.However, under expected utility theory, some people would be risk averse enough to prefer the sure thing, even though it has a lower expected value, while other less risk averse people would still choose the riskier, higher-mean gamble.
4 Indifference curvesIndifference curves for marginal rate of substitution for two products X and YGoods X and Y are perfect substitutesIndifference curves for perfect comple-ments X and Y
5 Why is Bernoulli’s concept wrong? Consider two people got info from brokers today:A is told her first bonus will be CZK out of maximum CZKB is told her first bonus will be CZK, which is CZK more than was expectedWho is happier today?Who is better off overall?Bernoulli’s concept focuses on long-term outcomes, but we work based on changes
6 About authors Daniel Kahneman With Amos Tversky and others, Kahneman established a cognitive basis for common human errors using heuristics and biases (Kahneman & Tversky, 1973; Kahneman, Slovic & Tversky, 1982; Tversky & Kahneman, ), and developed Prospect theory (Kahneman & Tversky, 1979).He was awarded the 2002 Nobel Memorial Prize in Economics for his work in Prospect theory. Currently, he is professor emeritus of psychology and public affairs at Princeton University's Woodrow Wilson School. Kahneman is a founding partner of The Greatest Good, a business and philanthropy consulting company.
7 About authors Amos Tversky cognitive and mathematical psychologist, a pioneer of cognitive science, a longtime collaborator of Daniel Kahneman, and a key figure in the discovery of systematic human cognitive bias and handling of risk. Much of his early work concerned the foundations of measurement.He was co-author of a three-volume treatise, Foundations of Measurement (recently reprinted). His early work with Kahneman focused on the psychology of prediction and probability judgment. Amos Tversky and Daniel Kahneman worked together to develop prospect theory, which aims to explain irrational human economic choices and is considered one of the seminal works of behavioral economics.
8 Where prospect theory stems from attempting to account for systematic features of human decision-making neither explained nor predicted by the Expected utility theoryfocused mainly on adapting the main parts of the previous model and expanding the model to accompany the systematic deviances of human decision-making observed in research
9 Inadequacy of the classical model Certainty effectAllais noted in 1953, people tend to overweight gambles with certain results over gambles with less certain results. On the other hand they overweight higher gains in improbable gambles over more probable but smaller gains (Kahneman and Tversky, 1979). It seems therefore, that through this effect reversibility of preferences is distorted.Reflection effectKahneman and Tversky (1979) point out, that while loss aversion may account for possible gains, in the domain of possible losses the expected utility curve mirrors its positive part resulting in risk seeking.Probabilistic insurance effectPurchase of insurance often serves as evidence for loss aversion and hence concavity of the utility function, but as Kahneman and Tversky (1979) show, people prefer insurance policies with limited coverage and zero or low deductibles over higher coverage policies with higher deductibles, clearly disobeying the concavity of loss-averse utility function. Moreover, Kahneman and Tversky (1979) suggest that people dislike probabilistic insurance (an insurance policy involving a small probability that the consumer will not be reimbursed) and demand more than a 20% reduction in the premium to compensate for a 1% default risk, again violating the concavity of expected utility function (Kahneman and Tversky, 1979; Wakker, Thaler and Tversky, 1997).Isolation effectDifferent choices are considered differently depending on, which sets of gambles are considered, while people tend to evaluate choices based on their distinguishing attributes (Kahneman and Tversky, 1979).
10 What is prospect theory Analogy with perception – similarly to perception, some information must be computed and cannot be directly derived from perceptionsThis computation influences our judgmentsChanges, not final states drive our judgmentsOur judgments depend on differences and changes to current stateAverage, not sums that drive our judgmentsOur judgments depend on the most representative state and not the sum of all states
11 Changes NOT states Judgments depends on changes and states Gamble 1: 50% chance to win 300 CZK50% chance to loose 200 CZKGamble 2:50% chance to own WEALTH CZK50% chance to own WEALTH CZKHow much do you need to accept the gamblePossible win is at least twice the loss
12 Value function Not expected utility but value of the gamble Loss aversion in domain of gains vs. domain of losses (2:1)Results in status quo bias
15 Heuristics and biasesIntuition, just like perception, deceives us in a systematic and consistent wayStatus quo biasAnchoring biasRepresentativeness heuristicAvailability heuristicIsolation effectRecognition heuristicSunk cost fallacyEtc.Dinnerware experiment for anchoringLinda a bank teller and feministCONTEXT!
17 Design of choice – anchoring 16%0%84%68%Dinnerware32%Zdroj: Dan Ariely: Jak drahé je zdarma, s (Predictably irrational)
18 Design of choice - representativeness There are 2 packs each containing 100 balls.One has 60 red and 40 white ballsThe other 40 red and 60 white ballsWhat is the probability you took from the urn with more red balls if you:pulled 3 red and 0 white balls?pulled 7 red and 3 white balls?How many words ending with –ing do you expect in text of 2000 words?How many words ending with –n- as the one before last letter do you expect in text of 2000 words?
19 Design of choice - availability Are there more words starting with R or with R on the third position in a word?Availability depends on how easy it is to recall an instance of certain kindTake air transport safetyTake probability of getting fined for fast drivingWords ing
20 Design of choice – isolation effect Redelmeister and Shafir (1995)Doctors were given a case, result was to send the patient to hip replacementThen half: reviewed the case and found you did not try Ibuprofen yetOther half: reviewed the case and found you did not try Ibuprofen and PiroxicamAriely (2009)Lindt for 15 cents or Hersheys for 1 cent: 73% to 27%Lindt for 14 cents or Hersheys for FREE: 31% to 69%
21 Design of choice – sunk cost fallacy Scenario 2: You didn't buy a ticket ahead of time. As you get to the theater you realize that $10 has fallen out of your pocket and is lost. Luckily, you still have enough to buy a ticket. Do you do so?Scenario 1: You bought a $10 non-refundable ticket to a show. (And note that you definitely would not have done so if the show cost $20.) As you get to the theater you realize you lost your ticket. Luckily, they have more available, still at $10. Do you buy another ticket?
22 Sunk cost fallacy with time? MonetaryTimeSource: Nina Bakošová: Diplomová práce – Making Exit DecisionsAlex Boese: Elephants on acid and other bizarre experiments
23 Design of choice – recognition heuristic Which city has a larger population?(a) Detroit (b) MilwaukeeGigerenzer and Goldstein (1996)90% German but only 60% American students got it rightThere is limited knowledge at all times (we cannot know all)Therefore we leverage algorithms that can help, such as Take the best - assumes a subjective rank order of cues according to their validities
24 Gerd GigerenzerGerman psychologist who has studied the use of bounded rationality and heuristics in decision making, especially in medicine. A critic of the work of Daniel Kahneman and Amos Tversky, he argues that heuristics should not lead us to conceive of human thinking as riddled with irrational cognitive biases, but rather to conceive rationality as an adaptive tool that is not identical to the rules of formal logic or the probability calculus.Gigerenzer is currently director at Max Planck Institute for Human Development and former Professor of Psychology at the University of Chicago and John M. Olin Distinguished Visiting Professor, School of Law at the University of Virginia.
25 Fast and frugal heuristics The algorithm is hardly a standard statistical tool for inductive inference: It does not use all available information, it is non- compensatory and nonlinear, and variants of it can violate transitivity.Herbert Simon proposed looking for models of bounded rationality instead of classical rationality.Simon (1956, 1982) argued that information-processing systems typically need to Satisfice rather than optimize. Satisficing, a blend of sufficing and satisfying, is a word of Scottish origin, which Simon uses to characterize algorithms that successfully deal with conditions of limited time, knowledge, or computational capacities.Gigerenzer proposes that such algorithms have ECOLOGICAL VALIDITY - it works fast and reliably enough given resources!
26 Convex or concave?1.) light comes from above (in relation to retinal coordinates), and2.) there is only one source of light.
27 I think, therefore I errWhy Can’t Players Predict Where a Fly Ball Lands?How does a baseball player catch a fly ball? It seems that the brain, at an unconscious level, somehow computes the trajectory of the ball. In The Selfish Gene, biologist Richard Dawkins writes:When a man throws a ball high in the air and catches it again, he behaves as if he had solved a set of differential equations in predicting the trajectory of the ball. He may neither know nor care what a differential equation is, but this does not affect his skill with the ball. At some subconscious level, something functionally equivalent to themathematical calculation is going on (1989: 96).Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student she was deeply concerned with issues of discrimination and social justice, and also participated in antinucleardemonstrations.Which of two alternatives is more probable:Linda is a bank teller,Linda is a bank teller and is active in the feminist movement?The majority of undergraduates (85 percent) chose the second alternative. Tversky and Kahneman argued that this is an error of judgment the “conjunction fallacy,” because it violates logic.Consider the following version of the Linda problem, Here the polysemy of the word probable is eliminated by using the phrase how many:There are 100 persons who fit the description above (that is, Linda’s). How many of them are:Bank tellers?Bank tellers and active in the feminist movement?This change is sufficient to make the apparently stable cognitive illusion largely disappear.Q: Are there more flowers or more primulas?Child: Primulas, but they all are flowers.Q: (Question repeated).Child: OK, more flowers. But why do you ask?Q: Is Linda more likely a bank teller or a bank tellerand active in the feminist movement?Child: If she is in philosophy, she would not be a bankteller. Therefore, it must be bank teller and activein the feminist movement.Q: Why?Child: Because it is both. One cannot understand thesequestions.Child: Because they make no sense.Let me summarize my argument. The use of logic and probability theory as a content-blind norm for good reasoning is widespread in recent experimental psychology.gaze heuristic, which works in situations where a ball is already high up in the air: Fixate on the ball, start running, and adjust your running speed so that the angle of gaze remains constant.
28 ReferencesBaron J. Thinking and deciding. 2nd ed. Cambridge, United Kingdom: Cambridge University Press, 1994.Gladwell, M. Blink: the power of thinking without thinking. London: Allan Lane, p.Gigerenzer, G.: I think, therefore I err. Social Research, 2005.Kahneman, D. Nobelprize.org [online] [cit ]. Prize Lecture.Ariely, D. Are we in control of our own decisions? [online] [cit ].