. 2019 Apr 30;10:923. doi: 10.3389/fpsyg.2019.00923

Table 1.

Pre-drive check on randomization and post-drive check on passenger social norms.

		Excluded + passive passenger			Excluded + risk-accepting passenger				Included (fair play + risk-accepting passenger
		N	Mean	SD	N	Mean	SD	Effect size §	N	Mean	SD	p	Effect size §§
	Measure (items; range)	Pre-drive randomization check^†

Study 1: males (N = 112)	Self-esteem^ns (1; 1–5)	40	4.03	0.83	36	4.28	0.61	0.34	36	3.94	0.53	0.10	0.60
	Susceptibility to peer pressure^ns (10; 1–4)	40	1.69	0.52	36	1.85	0.41	0.34	36	1.81	0.53	0.33	0.63
		Post-drive check on norms manipulation/perceptions of confederate passenger^‡
	Identification with passenger^∗∗∗ (6; 1–3)	39	1.99	0.40	36	2.39^aaa	0.47	0.92	36	2.30^a	0.50	<0.001	0.19
	Passenger approval of risky driving^∗∗ (5; 1–5)	39	2.83	0.68	36	4.13^aaa	0.73	1.84	36	4.25^aaa	0.70	<0.001	0.17

		Pre-drive randomization check^†

Study 2: females (N = 115)	Self-esteem^ns (1; 1–5)	39	3.63	0.71	39	3.62	0.94	0.01	37	3.38	0.98	0.39	0.25
	Susceptibility to peer pressure^ns (10; 1–4)	39	1.59	0.45	39	1.73	0.46	0.31	37	1.77	0.47	0.23	0.09
		Post-drive check on norms manipulation/perceptions of confederate passenger^‡
	Identification with passenger^∗∗∗ (6; 1–3)	39	2.04	0.26	39	2.27	0.47	0.61	37	2.46	0.34	<0.001	0.46
	Passenger approval of risky driving^∗∗ (5; 1–5)	39	2.47	0.50	39	4.12	0.84	2.39	37	4.47	0.50	<0.001	0.51

^†Prior to eventual group assignment; ^‡Administered after randomization and experimental drives. One-way ANOVA; post hoc comparisons with Tukey–Kramer adjustment; ^nsp > 0.05, ^∗∗p < 0.01, ^∗∗∗p < 0.001 for overall model. ^ap < 0.05, ^aaap < 0.001 when compared to excluded + passive passenger group. § Standardize mean differences for Excluded + passive passenger vs. Excluded plus risk-accepting passenger; §§ Standardized mean differences for Excluded plus risk-accepting vs. Included vs. risk-accepting passenger.