Rejection rates in questionnaire paradigm.

*Total numbers of participants in the corresponding game and condition. **For those offers, participants’ rejection rates in the non-informed IG in anonymous condition were (a) significantly lower than those in informed IG in the anonymous condition, and the informed IG and non-informed IG in the experimenter condition (p≤0.012, in χ2 tests) and (b) significantly larger than zero (p<0.001, in χ2 tests). See Supporting Text S3 for details.