Table 3

Effectiveness of pictorial warnings: mean weighted effect sizes (d) and heterogeneity statistics

	N	k	d	95% CI	p Value	Q	p Value	I²
Attention and recall
Attention attracting	18 379	6	0.79	(0.50 to 1.07)	0.001	301	0.001	98
Attention duration	169	2	1.74	(1.39 to 2.10)	0.001	<1	0.42	0
Response time	386	7	−0.03	(−0.23 to 0.17)	0.77	2	0.92	0
Recall/recognition of warning text	15 052	5	−0.03	(−0.06 to 0.02)	0.22	2	0.76	0
Warning reactions—cognitive, emotional and physiological
Cognitive elaboration	2082	3	1.70	(0.85 to 2.55)	0.001	105	0.001	98
Negative affective reactions	16 906	11	0.54	(0.44 to 0.64)	0.001	44	0.001	77
Credibility	20 222	9	0.15	(0.07 to 0.23)	0.001	35	0.001	77
Lower psychological reactance	14 324	4	−0.50	(−0.70 to −0.30)	0.001	61	0.001	95
Lower smoking cravings	3347	2	0.08	(0.01 to 0.16)	0.03	<1	0.68	0
Aversiveness	14 074	3	0.58	(0.42 to 0.75)	0.001	31	0.001	93
Attitudes/beliefs
Negative pack/brand attitudes	1260	7	0.79	(0.50 to 1.07)	0.001	28	0.001	78
Negative smoking attitudes	489	4	0.55	(0.28 to 0.83)	0.001	6	0.11	51
Perceived likelihood of harm	14 460	8	0.02	(−0.04 to 0.07)	0.65	13	0.06	48
Self-efficacy to quit	3385	2	0.01	(−0.06 to 0.08)	0.80	<1	0.96	0
Intentions
Lower willingness to pay	580	2	0.26	(0.02 to 0.50)	0.04	2	0.17	47
Intention to not start smoking	5016	4	1.82	(0.15 to 3.49)	0.03	336	0.001	99
Intention to quit smoking	16 671	8	0.54	(0.29 to 0.79)	0.001	256	0.001	97

n, number of participants; k, number of effect sizes; d, standardised mean difference (pooled effect size).