plonsky_2025_predicting
This paper introduces BEAST-GB, a hybrid model that combines the BEAST behavioural theory of risky choice with gradient-boosting machine learning, and shows it outperforms neural networks and dozens of existing models at predicting human decisions under risk and uncertainty, while also refining the underlying theory. The raw human data the paper releases are two datasets. exp0 (N = 240) is Experiment 2 of the CPC18 prediction competition run by the authors, i.e. the 60 held-out competition tasks (GameID 211–270): each participant faced one cohort (Set 8 or 9) of 30 tasks in random order and chose 25 times per task between two described lotteries, Option A and Option B (multi-outcome lotteries, ambiguity of Option B, and correlated payoffs are part of the task space), with no feedback in trials 1–5 and full feedback (obtained and forgone payoff) from trial 6; the 25 trials are pooled into 5 blocks of 5 for analysis. exp1 (N = 236) is the extensive-form-game data the paper's Supplementary Information re-analyses ("Additional datasets: Extensive form games"): the two choice prediction competitions of Ert, Erev & Roth (2011), 240 one-shot two-player games in four sets of 60 (estimation and prediction set of each competition), each played by 118 Player-1 participants (Stop/Continue, "Out"/"In" in the paper) and 118 Player-2 participants (Left/Right) under the strategy method. Note that CPC18's own second track (predicting individual decision makers) is not this data. Choices13k, HAB22, and the context-generalization analyses re-analyze previously published datasets and are excluded here. The response is a binary choice between prospects/game outcomes, and the study's central aim is predicting and generalizing human choice under risk.
Responses
180,000
18,000 held out
CORE effects
2 / 2
CORE test NLL (avg)
0.322
rank 1 of 7 models
Best model
CORE
test NLL (avg) 0.322
Likelihood of human responses
| model | PNLL | test NLL (avg) | test responses | train NLL (avg) | train responses |
|---|---|---|---|---|---|
| CORE best | 5,791.8 | 0.3218 | 18,000 | 0.3237 | 162,000 |
| CORE (no prediction errors) | 5,880.4 | 0.3267 | 18,000 | 0.3283 | 162,000 |
| CORE (no phonemes) | 5,825.2 | 0.3236 | 18,000 | 0.3213 | 162,000 |
| CORE (no forgetting) | 6,005.9 | 0.3337 | 18,000 | 0.3391 | 162,000 |
| CORE (no hierarchy) | 6,389.6 | 0.3550 | 18,000 | 0.3716 | 162,000 |
| Transformer | 6,264.1 | 0.3480 | 18,000 | 0.3602 | 162,000 |
| Centaur | 5,924.7 | 0.3291 | 18,000 | – | – |
Experiments
| exp | task class | participants | responses | conditions | simulated | effects |
|---|---|---|---|---|---|---|
| exp0 | RepeatedLotteryChoice | 240 | 180,000 | 1 | yes | expected_value_sensitivity, advantage_option_overchosen |
Behavioral effects
| effect | experiment | paper | CORE | CORE (no prediction errors) | CORE (no phonemes) | CORE (no forgetting) | CORE (no hierarchy) |
|---|---|---|---|---|---|---|---|
expected_value_sensitivity | exp0 | +0.330 | ✓ yes +0.339 | ✓ yes +0.323 | ✓ yes +0.325 | ✓ yes +0.228 | ✓ yes +0.053 |
P(choose option B) increases with the expected-value advantage of B over A, EV_B - EV_A; positive correlation, p<.05. | |||||||
advantage_option_overchosen | exp0 | +0.600 | ✓ yes +0.603 | ✓ yes +0.594 | ✓ yes +0.607 | ✓ yes +0.558 | ✗ no +0.433 |
among trials where EV_B > EV_A, option B is chosen significantly more than 50% of the time (proportion test), p<.05. | |||||||
Transcript
You will play a series of games. In each game you choose repeatedly between two lotteries, Option A and Option B, for 25 trials. For the first 5 trials of each game you get no feedback; from the 6th trial on, after each choice you see both the payoff you received and the payoff you would have received from the other option. In some games the probabilities of Option B's outcomes are not shown. On each trial, press A to choose Option A or B to choose Option B. Game (presentation 1): Option A pays 3. Option B pays 74 with probability 0.2, otherwise -20. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press B. You receive 74; you would have received 3. Trial 6: You press A. You receive 3; you would have received -20. Trial 7: You press A. You receive 3; you would have received 74. Trial 8: You press B. You receive -20; you would have received 3. Trial 9: You press B. You receive 74; you would have received 3. Trial 10: You press A. You receive 3; you would have received 74. Trial 11: You press A. You receive 3; you would have received -20. Trial 12: You press B. You receive -20; you would have received 3. Trial 13: You press B. You receive -20; you would have received 3. Trial 14: You press B. You receive -20; you would have received 3. Trial 15: You press A. You receive 3; you would have received -20. Trial 16: You press A. You receive 3; you would have received -20. Trial 17: You press A. You receive 3; you would have received -20. Trial 18: You press A. You receive 3; you would have received -20. Trial 19: You press A. You receive 3; you would have received 74. Trial 20: You press B. You receive -20; you would have received 3. Trial 21: You press B. You receive -20; you would have received 3. Trial 22: You press B. You receive -20; you would have received 3. Trial 23: You press B. You receive -20; you would have received 3. Trial 24: You press A. You receive 3; you would have received -20. Game (presentation 2): Option A pays 3. Option B pays 68 with probability 0.01, otherwise -1. Trial 0: You press B. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 3; you would have received -1. Trial 6: You press A. You receive 3; you would have received -1. Trial 7: You press A. You receive 3; you would have received -1. Trial 8: You press A. You receive 3; you would have received -1. Trial 9: You press A. You receive 3; you would have received -1. Trial 10: You press A. You receive 3; you would have received -1. Trial 11: You press A. You receive 3; you would have received -1. Trial 12: You press A. You receive 3; you would have received -1. Trial 13: You press A. You receive 3; you would have received -1. Trial 14: You press A. You receive 3; you would have received -1. Trial 15: You press A. You receive 3; you would have received -1. Trial 16: You press A. You receive 3; you would have received -1. Trial 17: You press B. You receive -1; you would have received 3. Trial 18: You press A. You receive 3; you would have received -1. Trial 19: You press A. You receive 3; you would have received -1. Trial 20: You press A. You receive 3; you would have received -1. Trial 21: You press A. You receive 3; you would have received -1. Trial 22: You press A. You receive 3; you would have received -1. Trial 23: You press A. You receive 3; you would have received -1. Trial 24: You press A. You receive 3; you would have received -1. Game (presentation 3): Option A pays 19. Option B pays 59 with probability 0.005, 57 with probability 0.005, otherwise 16. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 19; you would have received 16. Trial 6: You press A. You receive 19; you would have received 16. Trial 7: You press A. You receive 19; you would have received 16. Trial 8: You press A. You receive 19; you would have received 16. Trial 9: You press A. You receive 19; you would have received 16. Trial 10: You press A. You receive 19; you would have received 16. Trial 11: You press A. You receive 19; you would have received 16. Trial 12: You press A. You receive 19; you would have received 16. Trial 13: You press A. You receive 19; you would have received 16. Trial 14: You press A. You receive 19; you would have received 16. Trial 15: You press A. You receive 19; you would have received 16. Trial 16: You press A. You receive 19; you would have received 16. Trial 17: You press A. You receive 19; you would have received 16. Trial 18: You press A. You receive 19; you would have received 16. Trial 19: You press A. You receive 19; you would have received 16. Trial 20: You press A. You receive 19; you would have received 16. Trial 21: You press A. You receive 19; you would have received 16. Trial 22: You press A. You receive 19; you would have received 16. Trial 23: You press A. You receive 19; you would have received 16. Trial 24: You press A. You receive 19; you would have received 16. Game (presentation 4): Option A pays 12. Option B pays 83 with probability 0.2, otherwise -13. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive -13; you would have received 12. Trial 6: You press B. You receive -13; you would have received 12. Trial 7: You press B. You receive -13; you would have received 12. Trial 8: You press A. You receive 12; you would have received -13. Trial 9: You press A. You receive 12; you would have received -13. Trial 10: You press B. You receive -13; you would have received 12. Trial 11: You press A. You receive 12; you would have received -13. Trial 12: You press A. You receive 12; you would have received -13. Trial 13: You press A. You receive 12; you would have received -13. Trial 14: You press B. You receive -13; you would have received 12. Trial 15: You press A. You receive 12; you would have received -13. Trial 16: You press A. You receive 12; you would have received -13. Trial 17: You press A. You receive 12; you would have received -13. Trial 18: You press A. You receive 12; you would have received 83. Trial 19: You press A. You receive 12; you would have received 83. Trial 20: You press A. You receive 12; you would have received -13. Trial 21: You press A. You receive 12; you would have received -13. Trial 22: You press A. You receive 12; you would have received 83. Trial 23: You press A. You receive 12; you would have received -13. Trial 24: You press A. You receive 12; you would have received -13. Game (presentation 5): Option A pays -8. Option B pays -5 with probability 0.3, -7 with probability 0.15, -11 with probability 0.075, -19 with probability 0.075, otherwise -19. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive -8; you would have received -19. Trial 6: You press A. You receive -8; you would have received -5. Trial 7: You press A. You receive -8; you would have received -19. Trial 8: You press A. You receive -8; you would have received -19. Trial 9: You press A. You receive -8; you would have received -5. Trial 10: You press A. You receive -8; you would have received -5. Trial 11: You press A. You receive -8; you would have received -19. Trial 12: You press B. You receive -19; you would have received -8. Trial 13: You press A. You receive -8; you would have received -19. Trial 14: You press A. You receive -8; you would have received -11. Trial 15: You press A. You receive -8; you would have received -19. Trial 16: You press A. You receive -8; you would have received -5. Trial 17: You press A. You receive -8; you would have received -7. Trial 18: You press A. You receive -8; you would have received -5. Trial 19: You press A. You receive -8; you would have received -19. Trial 20: You press A. You receive -8; you would have received -19. Trial 21: You press A. You receive -8; you would have received -19. Trial 22: You press A. You receive -8; you would have received -5. Trial 23: You press A. You receive -8; you would have received -7. Trial 24: You press A. You receive -8; you would have received -19. Game (presentation 6): Option A pays 173 with probability 0.00078125, 109 with probability 0.00078125, 77 with probability 0.0015625, 61 with probability 0.003125, 53 with probability 0.00625, 49 with probability 0.0125, 47 with probability 0.025, otherwise -12. Option B pays -9. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive -12; you would have received -9. Trial 6: You press A. You receive -12; you would have received -9. Trial 7: You press A. You receive -12; you would have received -9. Trial 8: You press A. You receive -12; you would have received -9. Trial 9: You press A. You receive -12; you would have received -9. Trial 10: You press A. You receive -12; you would have received -9. Trial 11: You press A. You receive -12; you would have received -9. Trial 12: You press A. You receive -12; you would have received -9. Trial 13: You press B. You receive -9; you would have received -12. Trial 14: You press A. You receive -12; you would have received -9. Trial 15: You press A. You receive -12; you would have received -9. Trial 16: You press A. You receive -12; you would have received -9. Trial 17: You press B. You receive -9; you would have received -12. Trial 18: You press B. You receive -9; you would have received -12. Trial 19: You press B. You receive -9; you would have received -12. Trial 20: You press B. You receive -9; you would have received -12. Trial 21: You press A. You receive -12; you would have received -9. Trial 22: You press B. You receive -9; you would have received -12. Trial 23: You press B. You receive -9; you would have received -12. Trial 24: You press B. You receive -9; you would have received -12. Game (presentation 7): Option A pays 21 with probability 0.3, 19 with probability 0.3, otherwise 10. Option B pays 75 or -49; the probabilities are not shown. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 10; you would have received -49. Trial 6: You press A. You receive 10; you would have received -49. Trial 7: You press A. You receive 19; you would have received 75. Trial 8: You press A. You receive 10; you would have received 75. Trial 9: You press A. You receive 10; you would have received 75. Trial 10: You press A. You receive 10; you would have received -49. Trial 11: You press A. You receive 19; you would have received 75. Trial 12: You press A. You receive 10; you would have received -49. Trial 13: You press A. You receive 10; you would have received 75. Trial 14: You press A. You receive 10; you would have received 75. Trial 15: You press A. You receive 21; you would have received -49. Trial 16: You press A. You receive 10; you would have received -49. Trial 17: You press A. You receive 10; you would have received -49. Trial 18: You press A. You receive 19; you would have received -49. Trial 19: You press A. You receive 21; you would have received 75. Trial 20: You press A. You receive 19; you would have received -49. Trial 21: You press A. You receive 10; you would have received -49. Trial 22: You press A. You receive 19; you would have received -49. Trial 23: You press A. You receive 21; you would have received 75. Trial 24: You press A. You receive 21; you would have received 75. Game (presentation 8): Option A pays 1. Option B pays 27 or 1; the probabilities are not shown. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 1; you would have received 1. Trial 6: You press B. You receive 1; you would have received 1. Trial 7: You press B. You receive 1; you would have received 1. Trial 8: You press B. You receive 1; you would have received 1. Trial 9: You press B. You receive 1; you would have received 1. Trial 10: You press B. You receive 1; you would have received 1. Trial 11: You press B. You receive 1; you would have received 1. Trial 12: You press B. You receive 1; you would have received 1. Trial 13: You press B. You receive 1; you would have received 1. Trial 14: You press B. You receive 1; you would have received 1. Trial 15: You press B. You receive 1; you would have received 1. Trial 16: You press B. You receive 1; you would have received 1. Trial 17: You press B. You receive 1; you would have received 1. Trial 18: You press B. You receive 1; you would have received 1. Trial 19: You press B. You receive 1; you would have received 1. Trial 20: You press B. You receive 1; you would have received 1. Trial 21: You press B. You receive 1; you would have received 1. Trial 22: You press B. You receive 1; you would have received 1. Trial 23: You press B. You receive 1; you would have received 1. Trial 24: You press B. You receive 1; you would have received 1. Game (presentation 9): Option A pays 24 with probability 0.75, otherwise 20. Option B pays 17 with probability 0.95, otherwise 7. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 24; you would have received 17. Trial 6: You press A. You receive 20; you would have received 17. Trial 7: You press A. You receive 24; you would have received 17. Trial 8: You press A. You receive 20; you would have received 17. Trial 9: You press A. You receive 20; you would have received 17. Trial 10: You press A. You receive 24; you would have received 17. Trial 11: You press A. You receive 20; you would have received 7. Trial 12: You press A. You receive 24; you would have received 17. Trial 13: You press A. You receive 24; you would have received 17. Trial 14: You press A. You receive 20; you would have received 17. Trial 15: You press A. You receive 24; you would have received 17. Trial 16: You press A. You receive 20; you would have received 17. Trial 17: You press A. You receive 24; you would have received 17. Trial 18: You press A. You receive 20; you would have received 17. Trial 19: You press A. You receive 24; you would have received 17. Trial 20: You press A. You receive 24; you would have received 17. Trial 21: You press A. You receive 24; you would have received 17. Trial 22: You press A. You receive 24; you would have received 17. Trial 23: You press A. You receive 24; you would have received 17. Trial 24: You press A. You receive 24; you would have received 17. Game (presentation 10): Option A pays 19. Option B pays 26 or -19; the probabilities are not shown. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 19; you would have received 26. Trial 6: You press A. You receive 19; you would have received 26. Trial 7: You press A. You receive 19; you would have received 26. Trial 8: You press B. You receive 26; you would have received 19. Trial 9: You press B. You receive 26; you would have received 19. Trial 10: You press B. You receive 26; you would have received 19. Trial 11: You press B. You receive 26; you would have received 19. Trial 12: You press B. You receive 26; you would have received 19. Trial 13: You press B. You receive 26; you would have received 19. Trial 14: You press B. You receive 26; you would have received 19. Trial 15: You press B. You receive 26; you would have received 19. Trial 16: You press B. You receive 26; you would have received 19. Trial 17: You press B. You receive 26; you would have received 19. Trial 18: You press B. You receive 26; you would have received 19. Trial 19: You press B. You receive 26; you would have received 19. Trial 20: You press B. You receive 26; you would have received 19. Trial 21: You press B. You receive 26; you would have received 19. Trial 22: You press B. You receive -19; you would have received 19. Trial 23: You press B. You receive 26; you would have received 19. Trial 24: You press B. You receive 26; you would have received 19. Game (presentation 11): Option A pays 23. Option B pays 242 with probability 0.1, otherwise 2. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 23; you would have received 2. Trial 6: You press A. You receive 23; you would have received 2. Trial 7: You press A. You receive 23; you would have received 242. Trial 8: You press A. You receive 23; you would have received 2. Trial 9: You press A. You receive 23; you would have received 2. Trial 10: You press A. You receive 23; you would have received 2. Trial 11: You press A. You receive 23; you would have received 2. Trial 12: You press A. You receive 23; you would have received 2. Trial 13: You press A. You receive 23; you would have received 2. Trial 14: You press A. You receive 23; you would have received 2. Trial 15: You press A. You receive 23; you would have received 242. Trial 16: You press A. You receive 23; you would have received 2. Trial 17: You press A. You receive 23; you would have received 2. Trial 18: You press A. You receive 23; you would have received 2. Trial 19: You press B. You receive 2; you would have received 23. Trial 20: You press B. You receive 2; you would have received 23. Trial 21: You press B. You receive 2; you would have received 23. Trial 22: You press B. You receive 2; you would have received 23. Trial 23: You press B. You receive 2; you would have received 23. Trial 24: You press B. You receive 2; you would have received 23. Game (presentation 12): Option A pays 38 with probability 0.05, 36 with probability 0.025, 32 with probability 0.0125, 24 with probability 0.00625, 8 with probability 0.00625, otherwise 30. Option B pays one of 39, 38, 37, 36, 35, 34, 33, 32, 31, -1; the probabilities are not shown. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 30; you would have received 34. Trial 6: You press A. You receive 30; you would have received 34. Trial 7: You press A. You receive 30; you would have received 36. Trial 8: You press B. You receive 37; you would have received 30. Trial 9: You press B. You receive -1; you would have received 30. Trial 10: You press B. You receive 34; you would have received 30. Trial 11: You press B. You receive 35; you would have received 30. Trial 12: You press B. You receive 37; you would have received 30. Trial 13: You press B. You receive 34; you would have received 30. Trial 14: You press B. You receive 35; you would have received 30. Trial 15: You press B. You receive 34; you would have received 30. Trial 16: You press B. You receive 37; you would have received 30. Trial 17: You press B. You receive 32; you would have received 30. Trial 18: You press B. You receive 37; you would have received 30. Trial 19: You press B. You receive 34; you would have received 30. Trial 20: You press B. You receive 35; you would have received 30. Trial 21: You press B. You receive 37; you would have received 38. Trial 22: You press B. You receive -1; you would have received 30. Trial 23: You press B. You receive 32; you would have received 30. Trial 24: You press B. You receive 36; you would have received 30. Game (presentation 13): Option A pays 35 with probability 0.000195313, 34 with probability 0.0015625, 33 with probability 0.00546875, 32 with probability 0.0109375, 31 with probability 0.0136719, 30 with probability 0.0109375, 29 with probability 0.00546875, 28 with probability 0.0015625, 27 with probability 0.000195313, otherwise 2. Option B pays 28 or 14; the probabilities are not shown. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 14; you would have received 2. Trial 6: You press B. You receive 14; you would have received 2. Trial 7: You press B. You receive 14; you would have received 32. Trial 8: You press B. You receive 14; you would have received 2. Trial 9: You press B. You receive 14; you would have received 2. Trial 10: You press B. You receive 28; you would have received 2. Trial 11: You press B. You receive 14; you would have received 2. Trial 12: You press B. You receive 14; you would have received 2. Trial 13: You press B. You receive 28; you would have received 2. Trial 14: You press B. You receive 14; you would have received 2. Trial 15: You press B. You receive 14; you would have received 2. Trial 16: You press B. You receive 14; you would have received 2. Trial 17: You press B. You receive 14; you would have received 2. Trial 18: You press B. You receive 14; you would have received 2. Trial 19: You press B. You receive 14; you would have received 2. Trial 20: You press B. You receive 14; you would have received 2. Trial 21: You press B. You receive 14; you would have received 2. Trial 22: You press B. You receive 14; you would have received 2. Trial 23: You press B. You receive 14; you would have received 2. Trial 24: You press B. You receive 14; you would have received 2. Game (presentation 14): Option A pays -8. Option B pays 47 or -17; the probabilities are not shown. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 47; you would have received -8. Trial 6: You press B. You receive -17; you would have received -8. Trial 7: You press B. You receive 47; you would have received -8. Trial 8: You press B. You receive -17; you would have received -8. Trial 9: You press B. You receive -17; you would have received -8. Trial 10: You press B. You receive 47; you would have received -8. Trial 11: You press B. You receive -17; you would have received -8. Trial 12: You press B. You receive 47; you would have received -8. Trial 13: You press A. You receive -8; you would have received -17. Trial 14: You press B. You receive 47; you would have received -8. Trial 15: You press A. You receive -8; you would have received -17. Trial 16: You press B. You receive -17; you would have received -8. Trial 17: You press B. You receive -17; you would have received -8. Trial 18: You press B. You receive -17; you would have received -8. Trial 19: You press B. You receive -17; you would have received -8. Trial 20: You press B. You receive -17; you would have received -8. Trial 21: You press B. You receive -17; you would have received -8. Trial 22: You press A. You receive -8; you would have received -17. Trial 23: You press B. You receive -17; you would have received -8. Trial 24: You press A. You receive -8; you would have received 47. Game (presentation 15): Option A pays -9. Option B pays -2 with probability 0.00386719, -3 with probability 0.0309375, -4 with probability 0.108281, -5 with probability 0.216562, -6 with probability 0.270703, -7 with probability 0.216562, -8 with probability 0.108281, -9 with probability 0.0309375, -10 with probability 0.00386719, otherwise -36. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive -9; you would have received -9. Trial 6: You press B. You receive -5; you would have received -9. Trial 7: You press B. You receive -7; you would have received -9. Trial 8: You press B. You receive -5; you would have received -9. Trial 9: You press B. You receive -5; you would have received -9. Trial 10: You press B. You receive -7; you would have received -9. Trial 11: You press B. You receive -6; you would have received -9. Trial 12: You press B. You receive -6; you would have received -9. Trial 13: You press B. You receive -5; you would have received -9. Trial 14: You press B. You receive -8; you would have received -9. Trial 15: You press B. You receive -9; you would have received -9. Trial 16: You press B. You receive -6; you would have received -9. Trial 17: You press B. You receive -4; you would have received -9. Trial 18: You press B. You receive -5; you would have received -9. Trial 19: You press B. You receive -7; you would have received -9. Trial 20: You press B. You receive -8; you would have received -9. Trial 21: You press B. You receive -6; you would have received -9. Trial 22: You press B. You receive -6; you would have received -9. Trial 23: You press B. You receive -5; you would have received -9. Trial 24: You press B. You receive -6; you would have received -9. Game (presentation 16): Option A pays 0. Option B pays 10 with probability 0.00078125, 9 with probability 0.0046875, 8 with probability 0.0117188, 7 with probability 0.015625, 6 with probability 0.0117188, 5 with probability 0.0046875, 4 with probability 0.00078125, otherwise -2. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 0; you would have received -2. Trial 6: You press A. You receive 0; you would have received -2. Trial 7: You press A. You receive 0; you would have received -2. Trial 8: You press A. You receive 0; you would have received -2. Trial 9: You press A. You receive 0; you would have received -2. Trial 10: You press A. You receive 0; you would have received -2. Trial 11: You press A. You receive 0; you would have received -2. Trial 12: You press A. You receive 0; you would have received -2. Trial 13: You press A. You receive 0; you would have received -2. Trial 14: You press A. You receive 0; you would have received -2. Trial 15: You press A. You receive 0; you would have received -2. Trial 16: You press A. You receive 0; you would have received -2. Trial 17: You press A. You receive 0; you would have received -2. Trial 18: You press A. You receive 0; you would have received -2. Trial 19: You press A. You receive 0; you would have received -2. Trial 20: You press A. You receive 0; you would have received -2. Trial 21: You press A. You receive 0; you would have received -2. Trial 22: You press A. You receive 0; you would have received -2. Trial 23: You press A. You receive 0; you would have received -2. Trial 24: You press A. You receive 0; you would have received -2. Game (presentation 17): Option A pays -2 with probability 0.00390625, -3 with probability 0.03125, -4 with probability 0.109375, -5 with probability 0.21875, -6 with probability 0.273438, -7 with probability 0.21875, -8 with probability 0.109375, -9 with probability 0.03125, -10 with probability 0.00390625. Option B pays 95 with probability 0.1, 93 with probability 0.05, 89 with probability 0.05, otherwise -35. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive -7; you would have received 93. Trial 6: You press B. You receive -35; you would have received -9. Trial 7: You press B. You receive -35; you would have received -8. Trial 8: You press A. You receive -5; you would have received 95. Trial 9: You press A. You receive -3; you would have received -35. Trial 10: You press A. You receive -6; you would have received -35. Trial 11: You press A. You receive -7; you would have received -35. Trial 12: You press A. You receive -4; you would have received 93. Trial 13: You press A. You receive -7; you would have received -35. Trial 14: You press A. You receive -4; you would have received 95. Trial 15: You press A. You receive -6; you would have received -35. Trial 16: You press A. You receive -6; you would have received -35. Trial 17: You press A. You receive -7; you would have received -35. Trial 18: You press B. You receive 93; you would have received -5. Trial 19: You press A. You receive -6; you would have received -35. Trial 20: You press A. You receive -6; you would have received -35. Trial 21: You press A. You receive -4; you would have received 95. Trial 22: You press A. You receive -6; you would have received -35. Trial 23: You press A. You receive -4; you would have received -35. Trial 24: You press A. You receive -6; you would have received -35. Game (presentation 18): Option A pays 56 with probability 0.5, otherwise 0. Option B pays 41 with probability 0.6, otherwise 5. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 41; you would have received 56. Trial 6: You press B. You receive 5; you would have received 56. Trial 7: You press B. You receive 5; you would have received 56. Trial 8: You press B. You receive 41; you would have received 0. Trial 9: You press B. You receive 41; you would have received 0. Trial 10: You press A. You receive 0; you would have received 41. Trial 11: You press A. You receive 0; you would have received 5. Trial 12: You press A. You receive 56; you would have received 5. Trial 13: You press B. You receive 41; you would have received 56. Trial 14: You press A. You receive 56; you would have received 41. Trial 15: You press B. You receive 41; you would have received 0. Trial 16: You press B. You receive 5; you would have received 0. Trial 17: You press A. You receive 56; you would have received 41. Trial 18: You press A. You receive 0; you would have received 5. Trial 19: You press B. You receive 41; you would have received 56. Trial 20: You press B. You receive 41; you would have received 0. Trial 21: You press A. You receive 56; you would have received 5. Trial 22: You press B. You receive 41; you would have received 0. Trial 23: You press A. You receive 56; you would have received 5. Trial 24: You press B. You receive 5; you would have received 56. Game (presentation 19): Option A pays 47 with probability 0.4, otherwise -11. Option B pays 141 with probability 0.00625, 77 with probability 0.00625, 45 with probability 0.0125, 29 with probability 0.025, 21 with probability 0.05, 17 with probability 0.1, 15 with probability 0.2, otherwise 1. Trial 0: You press B. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 1; you would have received -11. Trial 6: You press B. You receive 1; you would have received -11. Trial 7: You press A. You receive -11; you would have received 1. Trial 8: You press A. You receive -11; you would have received 1. Trial 9: You press A. You receive 47; you would have received 15. Trial 10: You press A. You receive -11; you would have received 1. Trial 11: You press B. You receive 1; you would have received -11. Trial 12: You press B. You receive 1; you would have received -11. Trial 13: You press A. You receive 47; you would have received 45. Trial 14: You press B. You receive 21; you would have received 47. Trial 15: You press B. You receive 1; you would have received -11. Trial 16: You press B. You receive 15; you would have received 47. Trial 17: You press B. You receive 1; you would have received -11. Trial 18: You press B. You receive 45; you would have received 47. Trial 19: You press B. You receive 21; you would have received 47. Trial 20: You press B. You receive 1; you would have received -11. Trial 21: You press A. You receive -11; you would have received 1. Trial 22: You press A. You receive -11; you would have received 1. Trial 23: You press A. You receive -11; you would have received 1. Trial 24: You press A. You receive -11; you would have received 1. Game (presentation 20): Option A pays 22 with probability 0.75, otherwise 10. Option B pays 29 with probability 0.75, otherwise -3. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 10; you would have received 29. Trial 6: You press A. You receive 10; you would have received 29. Trial 7: You press A. You receive 22; you would have received 29. Trial 8: You press A. You receive 22; you would have received 29. Trial 9: You press A. You receive 22; you would have received -3. Trial 10: You press A. You receive 22; you would have received 29. Trial 11: You press A. You receive 10; you would have received 29. Trial 12: You press A. You receive 22; you would have received 29. Trial 13: You press A. You receive 10; you would have received 29. Trial 14: You press A. You receive 10; you would have received 29. Trial 15: You press A. You receive 10; you would have received 29. Trial 16: You press B. You receive 29; you would have received 22. Trial 17: You press B. You receive 29; you would have received 22. Trial 18: You press B. You receive 29; you would have received 22. Trial 19: You press A. You receive 22; you would have received 29. Trial 20: You press B. You receive -3; you would have received 22. Trial 21: You press B. You receive 29; you would have received 22. Trial 22: You press B. You receive -3; you would have received 22. Trial 23: You press B. You receive -3; you would have received 10. Trial 24: You press B. You receive 29; you would have received 22. Game (presentation 21): Option A pays 64 with probability 0.1, 62 with probability 0.05, 58 with probability 0.025, 50 with probability 0.025, otherwise -13. Option B pays 55 with probability 0.2, 53 with probability 0.1, 49 with probability 0.1, otherwise -43. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 49; you would have received -13. Trial 6: You press B. You receive -43; you would have received -13. Trial 7: You press B. You receive 49; you would have received -13. Trial 8: You press A. You receive -13; you would have received 49. Trial 9: You press A. You receive -13; you would have received -43. Trial 10: You press A. You receive 64; you would have received 49. Trial 11: You press A. You receive -13; you would have received -43. Trial 12: You press B. You receive 55; you would have received -13. Trial 13: You press A. You receive -13; you would have received -43. Trial 14: You press B. You receive 55; you would have received 50. Trial 15: You press A. You receive -13; you would have received -43. Trial 16: You press A. You receive 64; you would have received -43. Trial 17: You press B. You receive 55; you would have received -13. Trial 18: You press A. You receive -13; you would have received -43. Trial 19: You press B. You receive 55; you would have received -13. Trial 20: You press A. You receive 64; you would have received 49. Trial 21: You press A. You receive -13; you would have received 53. Trial 22: You press A. You receive 58; you would have received 55. Trial 23: You press B. You receive 53; you would have received -13. Trial 24: You press B. You receive 55; you would have received 62. Game (presentation 22): Option A pays 12 with probability 0.2475, 8 with probability 0.2475, 6 with probability 0.495, otherwise 5. Option B pays 10 with probability 0.0625, 9 with probability 0.25, 8 with probability 0.375, 7 with probability 0.25, 6 with probability 0.0625. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 8; you would have received 12. Trial 6: You press B. You receive 8; you would have received 6. Trial 7: You press B. You receive 8; you would have received 6. Trial 8: You press A. You receive 8; you would have received 8. Trial 9: You press B. You receive 10; you would have received 6. Trial 10: You press A. You receive 12; you would have received 7. Trial 11: You press A. You receive 12; you would have received 9. Trial 12: You press B. You receive 8; you would have received 12. Trial 13: You press B. You receive 8; you would have received 8. Trial 14: You press B. You receive 8; you would have received 12. Trial 15: You press B. You receive 9; you would have received 8. Trial 16: You press B. You receive 8; you would have received 8. Trial 17: You press A. You receive 6; you would have received 8. Trial 18: You press A. You receive 6; you would have received 10. Trial 19: You press B. You receive 6; you would have received 12. Trial 20: You press B. You receive 7; you would have received 6. Trial 21: You press B. You receive 9; you would have received 6. Trial 22: You press A. You receive 8; you would have received 8. Trial 23: You press A. You receive 6; you would have received 8. Trial 24: You press A. You receive 6; you would have received 8. Game (presentation 23): Option A pays 32 with probability 0.5, otherwise 14. Option B pays 19 with probability 0.061875, 18 with probability 0.2475, 17 with probability 0.37125, 16 with probability 0.2475, 15 with probability 0.061875, otherwise 16. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 32; you would have received 16. Trial 6: You press A. You receive 14; you would have received 17. Trial 7: You press A. You receive 14; you would have received 17. Trial 8: You press A. You receive 14; you would have received 17. Trial 9: You press A. You receive 32; you would have received 18. Trial 10: You press A. You receive 32; you would have received 17. Trial 11: You press A. You receive 14; you would have received 16. Trial 12: You press A. You receive 14; you would have received 16. Trial 13: You press A. You receive 32; you would have received 17. Trial 14: You press A. You receive 14; you would have received 18. Trial 15: You press A. You receive 32; you would have received 17. Trial 16: You press A. You receive 14; you would have received 18. Trial 17: You press A. You receive 14; you would have received 16. Trial 18: You press A. You receive 14; you would have received 16. Trial 19: You press A. You receive 14; you would have received 18. Trial 20: You press A. You receive 32; you would have received 16. Trial 21: You press A. You receive 32; you would have received 17. Trial 22: You press A. You receive 32; you would have received 16. Trial 23: You press A. You receive 32; you would have received 18. Trial 24: You press A. You receive 14; you would have received 16. Game (presentation 24): Option A pays 29 with probability 0.0015625, 28 with probability 0.0125, 27 with probability 0.04375, 26 with probability 0.0875, 25 with probability 0.109375, 24 with probability 0.0875, 23 with probability 0.04375, 22 with probability 0.0125, 21 with probability 0.0015625, otherwise 5. Option B pays 49 with probability 0.00015625, 48 with probability 0.0009375, 47 with probability 0.00234375, 46 with probability 0.003125, 45 with probability 0.00234375, 44 with probability 0.0009375, 43 with probability 0.00015625, otherwise 8. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 8; you would have received 5. Trial 6: You press B. You receive 8; you would have received 5. Trial 7: You press B. You receive 8; you would have received 25. Trial 8: You press B. You receive 8; you would have received 5. Trial 9: You press B. You receive 8; you would have received 26. Trial 10: You press B. You receive 8; you would have received 5. Trial 11: You press B. You receive 8; you would have received 5. Trial 12: You press A. You receive 27; you would have received 8. Trial 13: You press B. You receive 8; you would have received 24. Trial 14: You press B. You receive 8; you would have received 5. Trial 15: You press B. You receive 8; you would have received 5. Trial 16: You press B. You receive 8; you would have received 5. Trial 17: You press B. You receive 8; you would have received 5. Trial 18: You press B. You receive 8; you would have received 26. Trial 19: You press B. You receive 8; you would have received 5. Trial 20: You press B. You receive 8; you would have received 24. Trial 21: You press B. You receive 8; you would have received 24. Trial 22: You press B. You receive 8; you would have received 24. Trial 23: You press A. You receive 23; you would have received 8. Trial 24: You press A. You receive 25; you would have received 8. Game (presentation 25): Option A pays 98 with probability 0.0125, 97 with probability 0.05, 96 with probability 0.075, 95 with probability 0.05, 94 with probability 0.0125, otherwise 3. Option B pays 59 with probability 0.5, otherwise -19. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 3; you would have received 59. Trial 6: You press A. You receive 3; you would have received -19. Trial 7: You press A. You receive 3; you would have received 59. Trial 8: You press A. You receive 3; you would have received -19. Trial 9: You press A. You receive 3; you would have received -19. Trial 10: You press B. You receive -19; you would have received 94. Trial 11: You press B. You receive 59; you would have received 97. Trial 12: You press A. You receive 3; you would have received -19. Trial 13: You press A. You receive 3; you would have received -19. Trial 14: You press A. You receive 3; you would have received -19. Trial 15: You press A. You receive 3; you would have received -19. Trial 16: You press A. You receive 3; you would have received 59. Trial 17: You press A. You receive 3; you would have received -19. Trial 18: You press A. You receive 97; you would have received 59. Trial 19: You press A. You receive 3; you would have received 59. Trial 20: You press A. You receive 3; you would have received -19. Trial 21: You press A. You receive 3; you would have received -19. Trial 22: You press A. You receive 3; you would have received -19. Trial 23: You press A. You receive 3; you would have received -19. Trial 24: You press A. You receive 3; you would have received 59. Game (presentation 26): Option A pays 14 with probability 0.8, otherwise 13. Option B pays 35 with probability 0.00078125, 34 with probability 0.0046875, 33 with probability 0.0117188, 32 with probability 0.015625, 31 with probability 0.0117188, 30 with probability 0.0046875, 29 with probability 0.00078125, otherwise 12. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 12; you would have received 14. Trial 6: You press B. You receive 12; you would have received 14. Trial 7: You press B. You receive 12; you would have received 14. Trial 8: You press B. You receive 12; you would have received 14. Trial 9: You press A. You receive 14; you would have received 12. Trial 10: You press A. You receive 14; you would have received 12. Trial 11: You press A. You receive 14; you would have received 12. Trial 12: You press A. You receive 14; you would have received 12. Trial 13: You press A. You receive 14; you would have received 12. Trial 14: You press A. You receive 13; you would have received 12. Trial 15: You press A. You receive 14; you would have received 12. Trial 16: You press A. You receive 14; you would have received 12. Trial 17: You press A. You receive 14; you would have received 12. Trial 18: You press A. You receive 14; you would have received 12. Trial 19: You press A. You receive 13; you would have received 12. Trial 20: You press A. You receive 13; you would have received 12. Trial 21: You press A. You receive 14; you would have received 12. Trial 22: You press A. You receive 13; you would have received 12. Trial 23: You press A. You receive 13; you would have received 31. Trial 24: You press A. You receive 14; you would have received 12. Game (presentation 27): Option A pays -8. Option B pays 112 with probability 0.015625, 48 with probability 0.015625, 16 with probability 0.03125, 0 with probability 0.0625, -8 with probability 0.125, -12 with probability 0.25, -14 with probability 0.5. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press B. You receive -12; you would have received -8. Trial 6: You press B. You receive -14; you would have received -8. Trial 7: You press A. You receive -8; you would have received -8. Trial 8: You press B. You receive 0; you would have received -8. Trial 9: You press B. You receive -12; you would have received -8. Trial 10: You press A. You receive -8; you would have received -14. Trial 11: You press A. You receive -8; you would have received -12. Trial 12: You press A. You receive -8; you would have received -14. Trial 13: You press A. You receive -8; you would have received -14. Trial 14: You press A. You receive -8; you would have received 16. Trial 15: You press A. You receive -8; you would have received -12. Trial 16: You press A. You receive -8; you would have received -12. Trial 17: You press A. You receive -8; you would have received -14. Trial 18: You press B. You receive -12; you would have received -8. Trial 19: You press B. You receive -12; you would have received -8. Trial 20: You press B. You receive -12; you would have received -8. Trial 21: You press B. You receive -12; you would have received -8. Trial 22: You press B. You receive -12; you would have received -8. Trial 23: You press B. You receive 0; you would have received -8. Trial 24: You press B. You receive -14; you would have received -8. Game (presentation 28): Option A pays 18. Option B pays 34 with probability 0.1, otherwise 19. Trial 0: You press B. (no feedback) Trial 1: You press B. (no feedback) Trial 2: You press B. (no feedback) Trial 3: You press B. (no feedback) Trial 4: You press B. (no feedback) Trial 5: You press B. You receive 19; you would have received 18. Trial 6: You press B. You receive 19; you would have received 18. Trial 7: You press B. You receive 19; you would have received 18. Trial 8: You press B. You receive 34; you would have received 18. Trial 9: You press B. You receive 19; you would have received 18. Trial 10: You press B. You receive 19; you would have received 18. Trial 11: You press B. You receive 19; you would have received 18. Trial 12: You press B. You receive 19; you would have received 18. Trial 13: You press B. You receive 19; you would have received 18. Trial 14: You press B. You receive 19; you would have received 18. Trial 15: You press B. You receive 19; you would have received 18. Trial 16: You press B. You receive 34; you would have received 18. Trial 17: You press B. You receive 19; you would have received 18. Trial 18: You press B. You receive 19; you would have received 18. Trial 19: You press B. You receive 19; you would have received 18. Trial 20: You press B. You receive 19; you would have received 18. Trial 21: You press B. You receive 19; you would have received 18. Trial 22: You press B. You receive 19; you would have received 18. Trial 23: You press B. You receive 19; you would have received 18. Trial 24: You press B. You receive 19; you would have received 18. Game (presentation 29): Option A pays 2. Option B pays one of 11, 3, -1, -3; the probabilities are not shown. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 2; you would have received -1. Trial 6: You press A. You receive 2; you would have received -3. Trial 7: You press A. You receive 2; you would have received -3. Trial 8: You press A. You receive 2; you would have received -3. Trial 9: You press A. You receive 2; you would have received -3. Trial 10: You press A. You receive 2; you would have received 3. Trial 11: You press A. You receive 2; you would have received -1. Trial 12: You press A. You receive 2; you would have received -3. Trial 13: You press A. You receive 2; you would have received -1. Trial 14: You press A. You receive 2; you would have received 11. Trial 15: You press A. You receive 2; you would have received -3. Trial 16: You press A. You receive 2; you would have received 11. Trial 17: You press A. You receive 2; you would have received -3. Trial 18: You press A. You receive 2; you would have received -1. Trial 19: You press A. You receive 2; you would have received -3. Trial 20: You press A. You receive 2; you would have received 11. Trial 21: You press A. You receive 2; you would have received -3. Trial 22: You press A. You receive 2; you would have received -3. Trial 23: You press A. You receive 2; you would have received -1. Trial 24: You press A. You receive 2; you would have received 11. Game (presentation 30): Option A pays 15. Option B pays 44 with probability 0.0025, 43 with probability 0.005, 42 with probability 0.0025, otherwise 7. Trial 0: You press A. (no feedback) Trial 1: You press A. (no feedback) Trial 2: You press A. (no feedback) Trial 3: You press A. (no feedback) Trial 4: You press A. (no feedback) Trial 5: You press A. You receive 15; you would have received 7. Trial 6: You press A. You receive 15; you would have received 7. Trial 7: You press A. You receive 15; you would have received 7. Trial 8: You press A. You receive 15; you would have received 7. Trial 9: You press A. You receive 15; you would have received 7. Trial 10: You press A. You receive 15; you would have received 7. Trial 11: You press A. You receive 15; you would have received 7. Trial 12: You press A. You receive 15; you would have received 7. Trial 13: You press A. You receive 15; you would have received 7. Trial 14: You press A. You receive 15; you would have received 7. Trial 15: You press A. You receive 15; you would have received 7. Trial 16: You press A. You receive 15; you would have received 7. Trial 17: You press A. You receive 15; you would have received 7. Trial 18: You press A. You receive 15; you would have received 7. Trial 19: You press A. You receive 15; you would have received 7. Trial 20: You press A. You receive 15; you would have received 7. Trial 21: You press A. You receive 15; you would have received 7. Trial 22: You press A. You receive 15; you would have received 7. Trial 23: You press A. You receive 15; you would have received 7. Trial 24: You press A. You receive 15; you would have received 7.