Prosocial subjects | Individualistic subjects | Prosocial versus individualistic | |
---|---|---|---|
Proportion choosing the option with the other-bonus reward | |||
All trials | 0.550 ± 0.049 | 0.553 ± 0.028 | t(31) = 1.572, p = 0.126 |
Subset I | 0.388 ± 0.053 | 0.379 ± 0.032 | t(31) = 0.333, p = 0.741 |
Subset II | 0.722 ± 0.1666 | 0.707 ± 0.176 | t(31) = 1.341, p = 0.190 |
Negative log-likelihood of the responses of the SVO questionnaire | |||
SVO prosocial model | 0.637 ± 0.104 | 0.707 ± 0.090 | Better fitted to prosocial subjects (t(20) = 8.879, p < 0.001) |
SVO individualistic model | 0.812 ± 0.112 | 0.604 ± 0.060 | Better fitted to individualistic subjects (t(11) = 3.036, p = 0.039) |
Two additional tests that confirmed similar behaviors in our task between the prosocial and individualistic subjects, but distinct behavior in SVO questionnaire responses (for details, see Materials and Methods). In the first test for the behavior in our task, there was no difference between the two groups of subjects in the proportion choosing the option with other-bonus in all (other-bonus) trials, and even two types of subset trials (subsets I and II). In the second test for distinct behavior in the questionnaire responses, we employed a logistic regression analysis to the responses in the SVO questionnaire, devising corresponding SVO prosocial or individualistic model (see Materials and Methods). We found that the SVO choices by the prosocial and individualistic subjects were better fitted by the corresponding SVO model than by the other model. Therefore, whereas this confirms that their SVO choice behavior matched with the corresponding SVO model, it clearly indicates that the individualistic subjects behaved differently regarding other-bonus between our task and the questionnaire. Although they appreciated other-bonus in our task (as shown by their w0 being significantly larger than zero), they instead ignored them in their SVO choices.