Is there Some Format in Which CPT Violations are Attenuated? Michael H. Birnbaum Decision Research Center California State University, Fullerton

2 Stochastic Dominance If A stochastically dominates B, the probability of choosing B over A should not be signicantly greater than 1/2.

3 Analysis of Stochastic Dominance Transitivity: A  B and B  C  A  C Coalescing: GS = (x, p; x, q; z, r) ~ G = (x, p + q; z, r) Consequence Monotonicity:

4 RAM/TAX  Violations of Stochastic Dominance

5 Which gamble would you prefer to play? Gamble AGamble B 90 reds to win $96 05 blues to win $14 05 whites to win $12 85 reds to win $96 05 blues to win $90 10 whites to win $12 70% of undergrads choose B

6 Which of these gambles would you prefer to play? Gamble CGamble D 85 reds to win $96 05 greens to win $96 05 blues to win $14 05 whites to win $12 85 reds to win $96 05 greens to win $90 05 blues to win $12 05 whites to win $12 90% choose C over D

7 Violations of Stochastic Dominance Refute CPT/RDU, predicted by RAM/TAX Both RAM and TAX models predicted this violation of stochastic dominance before the experiment, using parameters fit to previous data.

8 Questions Is there some format in which CPT can be saved? We seek a format in which people satisfy stochastic dominance, show no event- splitting effects (violations of coalescing), and satisfy lower and upper cumulative independence.

9 Birnbaum & Navarrete (1998) $12 $14 $96$12 $90 $96 70% violations with 4 tests; n = 100. Similar results were obtained by Birnbaum, Patton, & Lott (1999) who used the same format with 5 new tests; n = 110.

10 I:.05 to win $12 J:.10 to win $12.05 to win $14.05 to win $90.90 to win $96.85 to win $96 Birnbaum & Martin (2003): 74% This study had a financial incentive; 6% of participants would win the prize of one of their chosen gambles. There were 74% violations, and 68% violated on this choice AND satisfied it in the split form.

11 Web Format (1999): 67%

12 Reversed Order: 63% 5. Which do you choose?  I:.90 probability to win $96.05 probability to win $14.05 probability to win $12 OR  J:.85 probability to win $96.05 probability to win $90.10 probability to win $12

13 Pie Charts: 65%, 66%

14 Tickets Format: 71%  I: 90 tickets to win $96 05 tickets to win $14 05 tickets to win $12 OR  J: 85 tickets to win $96 05 tickets to win $90 10 tickets to win $12

15 List Format: 61%, 64% I: $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96 $14 $12 OR J: $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96 $90 $12, $12

16 Semi-Split List: 56%* I: $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96 $14 $12 OR J: $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96, $96 $90 $12, $12

17 Marbles: 70%, 76%. Framing: not significant 5. Which do you choose?  I: 90 red marbles to win $96 05 blue marbles to win $14 05 white marbles to win $12 OR  J: 85 red marbles to win $96 05 blue marbles to win $90 10 white marbles to win $12

18 Decumulative Probability Format: 80% Violations 5. Which do you choose?  I:.90 probability to win $96 or more.95 probability to win $14 or more 1.00 probability to win $12 or more OR  J:.85 probability to win $96 or more.90 probability to win $90 or more 1.00 probability to win $12 or more (This had a significantly higher rate of violation)

19 New Formats not published as of

20 Unaligned Table: Coalesced

21 Unaligned Table: Split

22 Aligned Table: Coalesced

23 Aligned Table: Split Form

24 Violations of SD: from Web: Spring, 2004 New Tickets Format 84% 04% Unaligned Table 81% 12% Aligned Table 72% 08% Violations of SD in coalesced and split forms--Choices 5 and 11. (No. Participants: between-Ss: 141, 141, 151)

25 Summary: 23 Studies of SD, 8653 participants Huge effects of splitting vs. coalescing of branches- 70% vs 10% Small effects of education, gender Very Small effects of probability format, displays Miniscule effects of event framing (framed vs unframed)

26 Summary No format has yet been found that leads to data compatible with CPT. Many of the formats that have been used by others have been tested, and violations of SD have been found with all. Similar results with tests of UCI, LCI, and coalescing

27 Next Program: Testing Models of SD violation Are people just following some heuristic such as averaging the consequences and not attending to probability? Tests between TAX and RAM. It will turn out that TAX beats RAM and that both beat the heuristic.

28 For More Information: Download recent papers from this site. Follow links to “brief vita” and then to “in press” for recent papers.