1. Loss Aversion and the Endowment Effect

2. Our choices and our satisfaction are driven by the comparisons we make
Nearby additional
Alternative
Future
Past
Expected
Current
Multiple Alternative
Relevant Observed

3. Behavioral Economics Concepts
Loss Aversion; Endowment Effect; Status Quo Bias
Availability Effects
Endogenous Determination of Time Preference
Nearby additional
Alternative
Future
Past
Expected
Current
Hedonic Adaptation
Placebo Effect; Stereotypes
Multiple Alternative
Anchoring; Paradox of Choice
Peer Effects; Relative Standing
Relevant Observed

4. Reading
Predictably Irrational by Dan Ariely, Chapter 7: The High Price of Ownership

5. Two behavioral economics principles
1. The endowment effect
“Ownership creates satisfaction”
2. Loss aversion
“People are more motivated by avoiding a loss than acquiring a similar gain”
Kahneman and Tversky’s “Prospect Theory” describes how people evaluate gains and losses; it includes concepts such as status quo bias, loss aversion, and the endowment effect

6. The endowment effect People value a thing more once it becomes theirs
Ownership increases utility
Term originated by Richard Thaler (U. of Chicago)
Thaler, R. (University of Chicago), 1980, Toward a positive theory of consumer choice. Journal of Economic Behavior and Organization, March,

7. Students who did not get a mug reported the price they would be willing to pay to get one.
Students in every other seat were given university mugs. Then reported how much they would be willing to sell the mug for.
What happened?
The students with mugs priced them higher.
The students with no mugs priced them higher.
Both sets of students priced them about the same

8. Students with no mugs were willing to buy them, on average, for
$2.25
Students with the mugs were willing to sell them, on average, for
$4.50
Kahneman, D. (UC Berkley), Knetsch, J. (Simon Fraser U), Thaler, R. (Cornell), 1990, Experimental tests of the endowment effect and the Coase theorem. Journal of Political Economy, 98(6),

9. Class A
At the beginning, students given a coffee mug. At the end, given option to trade for a bar of Swiss chocolate.
Class B
Students given a chocolate bar. At the end, given option to trade for a coffee mug.
Class C
At the beginning, offered a choice between a chocolate bar or coffee mug. ? ? ?

10. Which class was most likely to choose the coffee mug?
Class A
At the beginning, students given a coffee mug. At the end, given option to trade for a bar of Swiss chocolate.
Class B
Students given a chocolate bar. At the end, given option to trade for a coffee mug.
Class C
At the beginning, offered a choice between a chocolate bar or coffee mug. ? ? ?
Which class was most likely to choose the coffee mug?

11. 89% 10% 59% ? ? ? Class A Class B Class C chose coffee mug
J. Knetsch (Simon Fraser U.), 1989, The endowment effect and evidence of nonreversible indifference curves. American Economic Review, 79,

12. When initially given peanut butter When initially given popsicle
33 chimpanzees given frozen-juice popsicle or tube of peanut butter (both familiar items) and then an opportunity to trade. ? ?
When initially given peanut butter
89%
Chose peanut butter
When initially given popsicle
42%
Chose peanut butter
Brosnan, S. (Emory), et al (Texas, Vanderbilt), 2007, Endowment effects in chimpanzees. Current Biology, 17,

13. Endowment effect in basketball tickets?
Dr. Dan Ariely, Duke University
Carmon, Ziv and Dan Ariely (2000), “Focusing on the Forgone: How Value Can Appear So Different to Buyers and Sellers,” Journal of Consumer Research, 27 (December), 360–70.

14. Duke basketball tickets experiment
At Duke, home-game basketball tickets are distributed by lottery
Ariely gets a list of the winners and losers
Calls the losers and asks how much they’d pay for a ticket ($170 on average)
Calls the winners and asks at what price they’d sell ($2,400)
This is evidence of the endowment effect

15. The endowment effect in art
Dr. Dan Gilbert, Harvard University
8:25-13:57

16. “pick your favorite, … you won’t be able to change your mind.” Group 2
Students in a non-credit photography class at Harvard picked two photos to develop then chose one to keep.
Group 1
“pick your favorite, … you won’t be able to change your mind.”
Group 2
If you change your mind within four days, you can swap it. I’ll call at the end to double-check.
Gilbert, D. (Harvard) & Ebert, J. (MIT), 2002, Decisions and revisions: The affective forecasting of changeable outcomes. Journal of Personality and Social Psychology, 82,

17. Both before and two days after their choice, participants were asked how much they liked their photograph from 1 (not at all) to 9 (very much)
Group 1
Change in satisfaction with picture
+1.3
Group 2
Change in satisfaction with picture
-1.8
Gilbert, D. (Harvard) & Ebert, J. (MIT), 2002, Decisions and revisions: The affective forecasting of changeable outcomes. Journal of Personality and Social Psychology, 82,

18. “The ratio of fructose to cellulose is an objective and unchanging property of apples, of course, but the experience of sweetness is a subjective property that increases when an apple becomes my apple”
Gilbert, D. (Harvard) & Ebert, J. (MIT), 2002, Decisions and revisions: The affective forecasting of changeable outcomes. Journal of Personality and Social Psychology, 82,

19. Students ranked 6 art posters
Students ranked 6 art posters. Next, allowed to take home either 3rd or 4th ranked poster. 15 minutes later, they rated their chosen poster again.
Group A: “if … any time in the next month, you can just let me know and we will exchange it for you.”
Creative commons licensed
Group B: Final choice, no exchanges.
Gilbert, D. (Harvard) & Ebert, J. (MIT), 2002, Decisions and revisions: The affective forecasting of changeable outcomes. Journal of Personality and Social Psychology, 82,

20. Change in ranking of the art poster before and after they chose to take it home.
-.07
+.71
Group A: “if … any time in the next month, you can just let me know and we will exchange it for you.”
Group B: Final choice, no exchanges.
Gilbert, D. (Harvard) & Ebert, J. (MIT), 2002, Decisions and revisions: The affective forecasting of changeable outcomes. Journal of Personality and Social Psychology, 82,

21. When allowed to pick their type of choice (changeable or unchangeable), people preferred:
66.3%
33.7%
Group A: “if … any time in the next month, you can just let me know and we will exchange it for you.”
Group B: Final choice, no exchanges.
Gilbert, D. (Harvard) & Ebert, J. (MIT), 2002, Decisions and revisions: The affective forecasting of changeable outcomes. Journal of Personality and Social Psychology, 82,

22. When asked which type of choice the typical student would prefer, they believed:
84.3%
15.7%
Group A: “if … any time in the next month, you can just let me know and we will exchange it for you.”
Group B: Final choice, no exchanges.
Gilbert, D. (Harvard) & Ebert, J. (MIT), 2002, Decisions and revisions: The affective forecasting of changeable outcomes. Journal of Personality and Social Psychology, 82,

23. Endowment effect and marketing
Money-back guarantees are offered by businesses because it reduces people’s resistance to trying a product
Once someone tries the product, the endowment effect may seal the deal

24. The IKEA effect
One’s sense of ownership of something increases when one invests more of one’s resources in it

25. Virtual ownership
We may feel as though we already own something if we can vividly imagine taking possession of it and living with it
This virtual ownership leads to a purchase and to actual ownership
Successful advertisements are good at enabling us to vividly imagine life with a product

26. Endowment effect and ideas
Once we accept an idea it is very difficult for us to let it go
This is how ideological rigidity sets in
We find it hard to take evidence seriously when it threatens an idea we feel is ours
We only consider evidence when it supports an idea we already believe

27. Diversification Bias Endowment Effect v.
“Our studies show that people prefer to have the opportunity to change their outcomes, …”
“but that, in fact, these opportunities inhibit the psychological processes that would otherwise have helped them manufacture satisfaction.”
Gilbert, D. (Harvard) & Ebert, J. (MIT), 2002, Decisions and revisions: The affective forecasting of changeable outcomes. Journal of Personality and Social Psychology, 82,

28. Dr. Dan Gilbert, Harvard University
Summary
14:19-19:05

29. - +
Loss Aversion

30. People are more motivated to avoid a loss than to acquire a similar gain.

31. Loss aversion and endowment effect
Once I own something, not having it becomes more painful, because it is a loss. If I don’t yet own it, then acquiring it is less important, because it is a gain.

32. Loss aversion and framing
If the same choice is framed as a loss, rather than as a gain, different decisions will be made.

33. Imagine that the US is preparing for the outbreak of an unusual disease, which is expected to kill 600 people. Choose a program to address the problem.
A: 200 people will be saved
B: 1/3 chance that 600 people will be saved. 2/3 chance that no people will be saved.

34. Imagine that the US is preparing for the outbreak of an unusual disease, which is expected to kill 600 people. Choose a program to address the problem.
72%
A: 200 people will be saved
B: 1/3 chance that 600 people will be saved. 2/3 chance that no people will be saved.
28%
Tversky, A. & Kahneman, D., 1981, The framing of decisions and the psychology of choice. Science, 211,

35. Imagine that the US is preparing for the outbreak of an unusual disease which is expected to kill 600 people. Choose a program to address the problem.
A: 400 people will die.
B: 1/3 chance that nobody will die. 2/3 chance that 600 people will die.

36. Imagine that the US is preparing for the outbreak of an unusual disease which is expected to kill 600 people. Choose a program to address the problem.
A: 400 people will die.
B: 1/3 chance that nobody will die. 2/3 chance that 600 people will die.
22%
78%
Tversky, A. & Kahneman, D., 1981, The framing of decisions and the psychology of choice. Science, 211,

37. Only the framing changed
600 people expected to die… 1/3 chance that nobody will die. 2/3 chance that 600 people will die.
600 people expected to die…
1/3 chance that 600 people will be saved. 2/3 chance that no people will be saved. =
78%
28%
So, this should be taught as a lesson in the interaction of loss aversion and framing? ≠
We will take great risks to avoid a loss. Reframing the same option as a loss changes the choices.
Tversky, A. & Kahneman, D., 1981, The framing of decisions and the psychology of choice. Science, 211,

38. 87% 84% 16% 13% We are less likely to risk to get an extra gain
Choose
A sure gain of $240
25% chance to gain $1000, and 75% chance to gain nothing
We are less likely to risk to get an extra gain
We are more likely to risk to avoid a loss
84%
16%
Choose
A sure loss of $750
75% chance to lose $1000, and 25% chance to lose nothing
13%
87%
Tversky, A. & Kahneman, D., 1981, The framing of decisions and the psychology of choice. Science, 211,

39. Framing a gamble as a loss or a gain
start – 5:54

40. When an investor sells a losing stock, she is committing to the loss.
Does loss aversion cause investors to hold losing stocks longer than winning stocks?

41. Study: Tracking 10,000 brokerage accounts from including 162,948 trades. In any one year… What share of losing stocks were sold? What share of gaining stocks were sold?

42. Study: Tracking 10,000 brokerage accounts from including 162,948 trades. In any one year… What share of losing stocks were sold? What share of gaining stocks were sold?
Note the strong opposing tax incentives
9.8%
14.8%
Odean, T. (UC-Davis), 1998, Are investors reluctant to realize their losses? Journal of Finance, 53,

43. Would investors have been better off to hold the winners and sell the losers?
Average 252-day gain after winners sold
Average 252-day gain after other stocks sold, but losing stocks held

44. Average 252-day gain after winners sold
Would investors have been better off to hold the winners and sell the losers?
Average 252-day gain after winners sold
Average 252-day gain after other stocks sold, but losing stocks held
+2.35% (better than market)
-1.06% (worse than market)
Odean, T. (UC-Davis), 1998, Are investors reluctant to realize their losses? Journal of Finance, 53,

45. Why losses hurt more
Is there a conflict between the core “elephant” side of the brain and the rational pre-frontal cortex “rider”. Why?
3:06-end

46. Using prospect theory to pursue your goals
Make it a habit (status quo bias)
Own it (endowment effect)
Fear its loss (loss aversion)
Wait a minute! What is prospect theory? Has it been discussed in the previous lectures?

47. 1. Make it a habit (Goal pursuit becomes the status quo)
“Creating a good habit requires much conscious effort, but once the groove has been produced the acts which make up a habitual pattern are not consciously willed.”
H. Keane (Australian National University), 2000, Setting yourself free: Techniques of recovery. Health, 4,

48. 2. Own it
Ownership creates satisfaction (endowment effect). By completely identifying yourself with a future goal, you become more attached to it
I claim my future

49. 3. Fear its loss
By “owning” a future goal, immediate temptations which put that future at risk can be framed as a potential loss.

50. Application question
Suppose you are advising a friend who wants to become a surgeon. What practical suggestions can you give to help her “own” her identity as a future surgeon?