Table 3. Mean cooperation levels.

Parameter	Effect size	SE	Confidence Intervals	Importance
Intercept	2.88	0.14	(2.61, 3.15)
Game type (asymmetric)	0.09	0.17	(-0.25, 0.42)	0.41
Focal player type (strong)	0.40	0.27	(-0.15, 0.94)	0.71
Game type x Focal player type	-0.74	0.34	(-1.41, -0.07)	0.41

Effect sizes, unconditional standard errors, confidence intervals and relative importance for parameters included in the top models investigating which factors affected the mean cooperation level chosen by the focal player in each game. Data from rounds where either the focal player or their partner opted out were excluded from the analysis.