Fig. 3.

Study 2: Proportion of participants who chose non-contribution (to keep their endowment), ingroup love, or outgroup hate in each game (IPD, original IPD-MD and positive variant of IPD-MD) and for each degree of enmity with the opposing group (none, weak-enmity, strong-enmity, morality-based). Ingroup love stands for the within-group pool in the original IPD-MD and for the between-group pool in the positive variant; outgroup hate stands for the between-group pool in the original IPD-MD, and for the within-group pool in the positive variant of the IPD-MD.