Table 5. Factors affecting whether players cooperated increased cooperation level.

Parameter	Effect size	SE	Confidence Interval	Importance
Intercept	-0.09	0.14	(-0.37, 0.19)
Partner punished in round n (yes)	-0.19	0.16	(-0.50, 0.12)	0.43
Focal player type (strong)	0.31	0.29	(-0.25, 0.88)	0.31
Game type (asymmetric)	0.10	0.13	(-0.17, 0.36)	0.22

Effect sizes, unconditional standard errors, confidence intervals and relative importance for parameters included in the top models investigating which factors affected whether or not focal players increased their cooperation level in round n+1 relative to round n (player didn’t change or decreased cooperation level = 0; player increased cooperation level = 1). Data were restricted to instances where the focal player chose a lower cooperation level than their partner in round n and exclude instances where either the focal player or their partner opted out in round n or round n+1 (n = 1655).