Keywords: statistics, repeated measures, mixed models, Iowa Gambling Task, prisoner's dilemma.
The pure within subjects design | |||||||
A1 | A2 | ||||||
b1 | b2 | b3 | b1 | b2 | b3 | ||
S1 | |||||||
S2 | |||||||
S3 | |||||||
S4 | |||||||
The pure between subjects design | |||||||
A1 | A2 | ||||||
b1 | b2 | b3 | b1 | b2 | b3 | ||
S1 | S5 | S9 | S13 | S17 | S21 | ||
S2 | S6 | S10 | S14 | S18 | S22 | ||
S3 | S7 | S11 | S15 | S19 | S23 | ||
S4 | S8 | S12 | S16 | S20 | S24 | ||
The mixed or split-plot design | |||||||
A1 | A2 | ||||||
b1 | b2 | b3 | b1 | b2 | b3 | ||
S1 | S5 | ||||||
S2 | S6 | ||||||
S3 | S7 | ||||||
S4 | S8 | ||||||
Modified Schedule - Decks | ||||
Payoff Variables | A | B | C | D |
Gain Amount | $50-$150 | $150-$250 | $50-$150 | $150-$250 |
Average Gain Amount | $100 | $200 | $100 | $200 |
Probability (Gain) | 0.5 | 0.5 | 0.8 | 0.5 |
Loss Amount | $100-$200 | $200-$300 | $200-$300 | $100-$200 |
Average Loss Amount | $150 | $250 | $250 | $150 |
First loss appears at card | 3 or 4 | 3 or 4 | 3 or 4 | 3 or 4 |
Expected value of a card | - $25 | - $25 | $30 | $25 |
Coding of good decks | 0 | 0 | 1 | 1 |
Coding of high-loss decks | 0 | 1 | 1 | 0 |
Coding of high-gain decks | 0 | 1 | 0 | 1 |
Model 1 | Model 2 | Model 3 | Model 4 | |||||
Fixed Effects | Estimate | t | Estimate | t | Estimate | t | Estimate | t |
(r)2-3(r)4-5(r)6-7(r)8-9 Intercept | 0.47 | 5.77*** | 0.56 | 0.87 | 0.31 | 0.47 | 0.11 | 0.17 |
Level 1 (Within-Subject) Variables: | ||||||||
Last Pay | -0.001 | -8.52*** | -0.001 | -8.52*** | -0.001 | -8.47*** | -0.001 | -8.59*** |
Last Pay from Deck | 0.002 | 20.12*** | 0.002 | 20.11*** | 0.002 | 19.86*** | 0.002 | 18.27*** |
Good Deck | 0.23 | 5.87*** | 0.23 | 5.87*** | 0.23 | 5.87*** | 0.24 | 6.15*** |
High Reward Deck | -0.28 | -7.24*** | -0.28 | -7.24*** | -1.52 | -7.68*** | -1.62 | -7.69*** |
High Loss Deck | 0.28 | 7.14*** | 0.28 | 7.14*** | 2.13 | 8.40*** | 2.16 | 8.42*** |
Early | ---- | ---- | ---- | ---- | 1.27 | 3.42*** | ||
Level 2 (Between-Subject) Variables: | ||||||||
BIS | ---- | ---- | -0.28 | -1.78 | -0.03 | -0.16 | -0.01 | -0.08 |
Extravert | ---- | ---- | -0.001 | -0.01 | -0.09 | -1.31 | -0.07 | -1.09 |
Negative mood | ---- | ---- | 0.23 | 1.17 | 0.32 | 1.55 | 0.31 | 1.49 |
Positive mood | ---- | ---- | 0.17 | 1.57 | 0.10 | 0.89 | 0.10 | 0.90 |
BIS*High Loss | ---- | ---- | ---- | ---- | -0.53 | -6.91*** | -0.53 | -6.32*** |
Extra * High Rew. | ---- | ---- | ---- | ---- | 0.17 | 5.37*** | 0.18 | 5.30*** |
Neg. mood * Hi Loss | ---- | ---- | ---- | ---- | -0.19 | -1.75 | -0.19 | -1.70 |
Pos. Mood * Hi Rew | ---- | ---- | ---- | ---- | 0.14 | 2.59** | 0.14 | 2.64** |
Early * BIS | ---- | ---- | ---- | ---- | ---- | ---- | -0.05 | -0.36 |
Early * Extravert | ---- | ---- | ---- | ---- | ---- | ---- | -0.10 | -1.67 |
Early * Hi Loss | ---- | ---- | ---- | ---- | ---- | ---- | -0.11 | -0.17 |
Early * Hi Rew | ---- | ---- | ---- | ---- | ---- | ---- | 0.60 | 1.27 |
Early * Bis * High Loss | ---- | ---- | ---- | ---- | ---- | ---- | -0.09 | -0.42 |
Early * Ex * Hi Rew | ---- | ---- | ---- | ---- | ---- | ---- | -0.08 | -0.92 |
Autoregressive (1) | -0.06 | -6.16*** | -0.06 | -6.18*** | -0.06 | -6.22*** | -0.06 | -6.64*** |
Condition | Trinary, Round 1 | Trinary, Round 2 | Feedback | Number of Subjects |
1 | X | X | 21 | |
2 | X | 19 | ||
3 | X | X | X | 22 |
4 | X | X | 21 | |
5 | X | 27 | ||
6 | 26 | |||
7 | X | X | 26 | |
8 | X | 23 | ||
Total | 185 | |||
Choices | Round 1 | Round 2 | Total | |
Opt-Out | 41% | 40% | 41% | |
Play | 59% | 60% | 59% | |
Total | 100% | 100% | 100% | |
N (choices) | 552 | 576 | 1128 | |
Defect | 63% | 68% | 65% | |
Cooperate | 37% | 32% | 35% | |
Total | 100% | 100% | 100% | |
N (choices) | 882 | 879 | 1761 | |
Subjects who did not give ratings on the attractiveness measure or who gave all others the same score were eliminated from the analysis. | ||||
Model 1 | Model 2 | Model 3 | ||||
Fixed Effects | Estimate | t | Estimate | t | Estimate | t |
(r)2-3(r)4-5(r)6-7 Intercept | 0.60 | 1.70 | -0.20 | -0.51 | 0.98 | 1.17 |
Level 1 (Within-Subject) Variables: | ||||||
Matrix 2 | 1.41 | 8.10*** | 1.39 | 7.64*** | 1.39 | 7.63*** |
Matrix 3 | 1.82 | 9.84*** | 1.81 | 9.41*** | 1.81 | 9.37*** |
Round 2 | -0.16 | -0.63 | -0.15 | -0.60 | -0.16 | -0.64 |
Male other | 0.04 | 0.26 | 0.06 | 0.39 | 0.07 | 0.42 |
Subject's rating of other's attractiveness | 0.08 | 2.51** | 0.14 | 3.61*** | 0.14 | 3.66*** |
Subject's expectation other will defect | -0.03 | -8.18*** | -0.02 | -5.05*** | -0.02 | -5.12*** |
Feedback | -0.54 | -1.60 | 2.40 | 3.35*** | 2.41 | 3.35*** |
Feedback by other's attractiveness | ---- | ---- | -0.19 | -2.85*** | -0.19 | -2.88** |
Feedback by expectation of other | ---- | ---- | -0.03 | -3.97*** | -0.03 | -3.91*** |
Level 2 (Between-Subject) Variables: | ||||||
Male subject | ---- | ---- | ---- | ---- | -0.49 | -1.33 |
Subject's self rating of attractiveness | ---- | ---- | ---- | ---- | -0.13 | -1.32 |
Autoregressive (1) | 0.13 | 3.41*** | 0.13 | 3.04** | 0.13 | 3.12** |
Model 1 | Model 2 | Model 3 | Model 4 | |||||
Fixed Effects | Estimate | t | Estimate | t | Estimate | t | Estimate | t |
(r)2-3(r)4-5(r)6-7(r)8-9 Intercept | 0.44 | 1.58 | 0.49 | 1.66 | 1.14 | 1.88 | 2.45 | 3.10** |
Level 1 (Within-Subject) Variables: | ||||||||
Matrix 2 | -0.65 | -4.60*** | -0.66 | -4.61*** | -0.66 | -4.60*** | -0.64 | -4.52*** |
Matrix 3 | 0.22 | 1.63 | 0.22 | 1.62 | 0.22 | 1.63 | 0.23 | 1.68 |
Round 2 | -0.12 | -0.78 | -0.12 | -0.77 | -0.11 | -0.75 | -0.12 | -0.78 |
Male other | -0.21 | -1.72 | -0.21 | -1.71 | -0.21 | -1.70 | -0.22 | -1.81 |
Other's attract. | 0.10 | 3.52*** | 0.09 | 3.09** | 0.09 | 3.17** | 0.07 | 2.10* |
Expectation of other | -0.03 | -10.94*** | -0.03 | -9.88*** | -0.03 | -9.90*** | -0.03 | -9.89*** |
Feedback | -0.26 | -1.18 | -0.55 | -0.93 | -0.55 | -0.94 | -0.58 | -0.99 |
Feedback X other attractiveness | ---- | ---- | 0.03 | 0.46 | 0.03 | 0.47 | 0.04 | 0.54 |
Feedback X expectation of other | ---- | ---- | 0.002 | 0.29 | 0.002 | 0.29 | 0.002 | 0.28 |
Level 2 (Between-Subject) Variables: | ||||||||
Male subject | ---- | ---- | ---- | ---- | 0.07 | 0.26 | -2.04 | -1.85 |
Self rating of attractiveness | ---- | ---- | ---- | ---- | -0.09 | -1.27 | -0.25 | -2.58** |
Male * self rating | ---- | ---- | ---- | ---- | ---- | ---- | 0.28 | 1.98* |
Both High Attract. | ---- | ---- | ---- | ---- | ---- | ---- | 0.55 | 2.31* |
Autoregressive (1) | 0.09 | 2.89** | 0.09 | 2.90** | 0.09 | 2.89** | 0.09 | 2.97** |