Article Figures & Data
Figures
- Figure 1.
The norm training task. A, The ultimatum game. Subjects played the role of Responder in the ultimatum game. In each round, a new partner (Proposer) made an offer $x of $20. Subjects decided to either accept (self got $x, partner got $20 − x) or reject (both got $0) the split. B, Visual display of the task. Each trial (60 trials in total) began with a new partner (blue square) making an offer (4 s). The offer was displayed for 4 s. Subjects (green square) indicated their decision to accept or reject the offer by moving the yellow arrow (self-paced). On every three of five trials (randomly ordered), subjects were asked to rate their feelings about the offer from 1 (sad face) to 9 (happy face) at a self-paced speed. The intertrial interval was 2–4 s. C, Offers were sampled from one of the three Gaussian distributions, orange curve (mean $4, SD $1.5), cyan curve (mean $8, SD $1.5), and purple curve (mean $12, SD $1.5). Group LM received low offers (orange curve) in the first 30 trials and medium offers (cyan curve) in the last 30 trials. Group HM received 30 high offers (purple curve) first and then 30 medium offers. Groups ML and MH both started with 30 medium offers, but received 30 low offers and high offers, respectively, in the second half of the task.
- Figure 2.
Norm and variance prediction errors. A, Average norm prediction errors by round for each group. B, Average variance prediction errors by round for each group.
- Figure 3.
Subjective feelings correlated with norm prediction errors, and both involved the mOFC/vmPFC activation. A, Voxels correlated with norm prediction errors, p < 0.05, FDR corrected. Peak voxel (4, 40, −16), t = 4.38. B, Emoticon ratings displayed a linear relationship with norm prediction errors. The correlation coefficient was r = 0.62. C, Voxels correlated with emoticon ratings of the offers received, p < 0.01, FDR corrected. Peak voxel (4, 40, −16), t = 4.75. D, ROI analysis using a 6-mm-radius spherical mOFC/vmPFC mask centered on the peak voxel (4, 50, −16) from Harvey et al. (2010). The averaged BOLD response displayed a linear relationship with norm prediction errors. Color bars display t scores.
- Figure 4.
Differential striatal and overlapping mOFC response to positive and negative norm prediction errors. A, Voxels correlated with positive norm prediction errors, p < 0.05, FDR corrected. B, Voxels correlated with negative norm prediction errors, p < 0.05, FDR corrected. mOFC was negatively correlated with negative norm prediction errors. C, Overlay of voxels from A (yellow); B, left (red); and B, right (green).
- Figure 5.
Anterior insula and striatum activity correlated with variance prediction errors. A, Voxels correlated with variance prediction errors, p < 0.05, FWE corrected. Right anterior insula, peak voxel (32, 24, −4), t = 8.70; right striatum peak voxel (12, 4, −8), t = 7.10. B, ROI analysis using a 6-mm-radius spherical mask of the right anterior insula centered on the voxel reported in Preuschoff et al. (2008). The BOLD responses of the right anterior insula displayed a U-shape relationship with norm prediction errors. Color bars display t scores.
- Figure 6.
Norm training effect in group HM and LM when both received medium offers. A, Average offers received by the group HM and LM along the course of the task. B, Comparison of the rejection rates between group LM (n = 34) and group HM (n = 31) when both received medium offers. Group LM preadapted to 30 low offers rejected medium offers $6–8 less frequently than group HM players who preadapted to 30 high offers, *p < 0.05. C, Comparison of the emoticon ratings between group LM and group HM when both received medium offers. Group LM players rated their feelings about medium offers $6–9 higher (happier) than group HM players, *p < 0.05. Error bars represent SE. D, SPM contrast between groups LM and HM in the last 30 trials when medium offers were revealed. Group LM had greater activation in the nucleus accumbens and ventromedial prefrontal cortex, p < 0.001, uncorrected. Nucleus accumbens (35 voxels), FDR corrected at cluster level, p < 0.05. Color bar displays t scores.
- Figure 7.
Negative norm prediction error and envy coefficient (alpha). A, Voxels correlated with the individual's sensitivity to the negative norm prediction errors, the envy coefficient (alpha). Second-level analysis on beta images correlated with negative norm prediction errors when offers were revealed. A simple regression using alpha was applied to those beta images. dACC was negatively correlated with alpha, p < 0.05, FDR corrected. B, Beta values from the peak voxel (8, 24, 36) of dACC had negative correlation with alpha, r = −0.39.
- Figure 8.
Brain regions correlated with feeling prediction errors. A, Voxels correlated with feeling norm prediction errors, FDR corrected, p < 0.01. Nucleus accumbens (8, 12, −8), t = 3.96; vmPFC (4, 40, −16), t = 5.01; posterior cingulate (−4, −32, 40), t = 4.65. B, Voxels correlated with feeling variance prediction errors, FDR corrected, p < 0.05. Right anterior insula (40, 20, 0), t = 4.69; left anterior insula (−32, 28, 4), t = 4.30. Color bars display t scores.
Tables
Estimate SE t value p value Constant 5.352 0.114 47.33 <2e-16 PE 0.616 0.025 24.51 <2e-16 VPE −0.003 0.006 −0.55 0.585 PE, Prediction error; VPE, variance prediction error. N = 123.
Mean Median SD Envy 3.38 1.75 3.69 Guilt 0.46 0 0.47 Temperature 1.84 0.96 2.15 Log likelihood 8.71 6.01 9.37 N = 123.
LM (N = 32) ML (N = 32) HM (N = 29) MH (N = 30) Average negative log-likelihood 13.57 11.15 5.44 4.12 Total N = 123.
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