TABLE A1.

Shapiro–Wilk test for normality.

	W	V	Z	Prob > z
Individual productivity	0.93718	5.186	3.652	0.0001
Group productivity	0.89132	8.973	4.868	0.0000
PGG round 1	0.96634	2.779	2.267	0.0117
PGG round 2	0.98081	1.584	1.021	0.1537
PGG combined	0.97133	2.367	1.912	0.0280
IOS	0.88231	9.473	4.98	0.0000
PANAS pos	0.87091	10.658	5.249	0.0000
PANAS neg	0.96356	3.009	2.444	0.0073
Intrinsic motivation	0.96879	2.577	2.1	0.0179
RR	0.95459	3.624	2.85	0.0022
SCL	0.84561	11.463	5.373	0.0000