A short intertemporal choice survey was submitted to 110 workers, mostly from the United States (51%) and India (42%) (40% female; mean age = 33). After discarding incomplete responses and those completed under 50 seconds, the usable sample size was n = 94.
Workers were tasked with the “French dinner problem” described in Loewenstein and Prelec (LP; 1993), which tests violations of independence in the context of intertemporal choice.
LP | AMT | ||||||
1. Which would you prefer if both were free? | n = 95 | n = 94 | |||||
A. Dinner at a fancy French restaurant | 86% | 64% | |||||
B. Dinner at a local Greek restaurant | 14% | 36% | |||||
For those who prefer French: | |||||||
2. Which would you prefer? | n = 82 | n = 60 | |||||
C. Dinner at the French restaurant on Friday in 1 month | 80% | 65% | |||||
D. Dinner at the French restaurant on Friday in 2 months | 20% | 35% | |||||
3. Which would you prefer? | n = 82 | n = 60 | |||||
E. Dinner at the French restaurant on Friday in | 43% | 78% | |||||
1 month and dinner at the Greek restaurant | |||||||
on Friday in 2 months | |||||||
F. Dinner at the Greek restaurant on Friday in | 57% | 22% | |||||
1 month and dinner at the French restaurant on | |||||||
Friday in 2 months |
Results from LP (1993; left column) and our study (right column) are posted in the table above. Among those who prefer a French dinner, our results show a relatively stronger preference for delayed consumption with the single-outcome event (i.e., Question 2). While LP finds a preference for sequential improvement in Question 3, our workers maintain a positive discount rate and do not opt for the sequential improvement.
We also included the intertemporal choice survey used in Kirby and Marakovic (KM; 1996) to test the independence of delay-discounting rate and monetary reward size. Workers were asked to choose between the following hypothetical pairings, ranked in increasing order by hyperbolic discounting parameter values (i.e. those values at which immediate and delayed rewards are equalized):
Choice Trials and Their Associated Discounting Parameter Values | ||||
Order | Choice Trial | Hyperbolic | %Ss (KM) | %Ss (AMT) |
4 | $34 tonight or $35 in 43 days | 0.0007 | 12 | 7 |
15 | $53 tonight or $55 in 55 days | 0.0007 | 12 | 17 |
7 | $83 tonight or $85 in 35 days | 0.0007 | 12 | 15 |
20 | $27 tonight or $30 in 35 days | 0.0032 | 17 | 18 |
9 | $48 tonight or $55 in 45 days | 0.0032 | 34 | 32 |
12 | $65 tonight or $75 in 50 days | 0.0031 | 44 | 28 |
8 | $21 tonight or $30 in 75 days | 0.0057 | 36 | 37 |
16 | $47 tonight or $60 in 50 days | 0.0055 | 57 | 49 |
14 | $30 tonight or $35 in 20 days | 0.0083 | 44 | 36 |
10 | $40 tonight or $65 in 70 days | 0.0089 | 67 | 49 |
3 | $67 tonight or $85 in 35 days | 0.0077 | 70 | 54 |
18 | $50 tonight or $80 in 70 days | 0.0086 | 74 | 54 |
11 | $25 tonight or $35 in 25 days | 0.016 | 68 | 53 |
2 | $40 tonight or $55 in 25 days | 0.015 | 71 | 52 |
19 | $45 tonight or $70 in 35 days | 0.0159 | 90 | 73 |
21 | $16 tonight or $30 in 35 days | 0.025 | 86 | 66 |
6 | $32 tonight or $55 in 20 days | 0.0359 | 94 | 77 |
17 | $40 tonight or $70 in 20 days | 0.0375 | 97 | 85 |
5 | $15 tonight or $35 in 10 days | 0.1333 | 99 | 86 |
13 | $24 tonight or $55 in 10 days | 0.1292 | 99 | 87 |
1 | $30 tonight or $85 in 14 days | 0.131 | 99 | N/A |
The last two columns show the percentage of subjects choosing the delayed reward on each trial. Our results show a relatively steeper discount function than KM, with an estimated median hyperbolic parameter value of 0.012 compared with 0.007 in KM. The 0.012 value indicates the median worker switched from choosing the immediate outcome to the delayed outcome between the 12th and 13th trial ranked in the table above.
References
Loewenstein, G., Prelec, D. (1993). Preferences for Sequences of Outcomes. Psychological Review 100(1), 91-108.
Kirby, K., Marakovic, N. (1996). Delay-discounting probabilistic rewards: Rates decrease as amounts increase. Psychonomic Bulletin & Review 3(1), 100-104.
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