Table S1.

Multilevel model predicting group performance

Variable	Slope	SE	df	t	P
Intercept	0.22	0.10	67	2.10	0.04
Time of performance	−0.04	0.05	48	−0.86	0.40
Cortisol, mean	0.14	0.33	67	0.41	0.68
Testosterone, mean	0.14	1.04	67	0.14	0.89
Time of performance × cortisol, mean	−0.10	0.15	48	−0.65	0.52
Time of performance × testosterone, mean	0.56	0.39	48	1.43	0.16
Cortisol, mean × testosterone, mean	−2.70	0.93	67	−2.90	0.01
Time of performance × cortisol, mean × testosterone, mean	0.00	0.39	48	−0.01	0.99
Time of day	0.04	0.06	67	0.66	0.51
No. of females	−0.08	0.34	67	−0.23	0.82
Group size	0.12	0.16	67	0.73	0.47

n = 74 groups for final performance measured on day 7, and n = 52 groups for interim performance measured on day 5. Time of performance refers to whether group performance was assessed in the interim (day 5) or at the end of the simulation (day 7).