Supplementary material for <G. Kong et al.> <Re-training automatic action tendencies to
approach cigarettes among adolescent smokers: a pilot study> <The American Journal of
Drug and Alcohol Abuse> <2015>
Data preparation
Following a standard procedure in bias assessment tasks (see 1,2–5), we removed reaction times
(RTs) below 200 ms, over 2000 ms and more than 3 SD above and below the mean on the SAAT to correct for outliers. Approximately, 5.3% of American data and 5.5% of Dutch data
were removed, which is within the normal range (1–8%; 6–8). The average RT accuracy of the
analytic sample was 92% (SD = 71%).
Internal reliability of the S-AAT at baseline was examined separately by site and image
type by calculating the Cronbach’s α using the bias scores for each image. Reliability of the
smoking bias (20 items, American: α = 0.57; Dutch: α = 0.53) and neutral bias (20 items,
American: α = 0.54, Dutch: α = 0.21) was fairly poor, but was in line with previous research (9)
and was not unusual for tests assessing cognitive bias using reaction-time based assessments
(10,11).
Supplementary Table 1. Repeated-measures ANOVA of smoking and neutral approach tendencies/biases at baseline and threemonth follow up as a function of treatment condition (treatment vs. sham) and site (USA vs. NL), separated by baseline smoking bias
(approach vs. avoidance).
Between sbjects
Treatment Condition (treatment vs. sham)
Site (USA vs. NL)
Within subjects
Smoke Bias Score
Smoke Bias × Site
Smoke Bias × Treatment Condition
Neutral Bias Score
Neutral Bias × Site
Neutral Bias × Treatment Condition
Smoking Approach Bias (n = 17)
F
p
η2
Smoking Avoidance Bias (n = 18)
F
p
η2
0.20
3.72
0.66
0.08
0.02
0.22
0.05
9.98
0.82
0.007
0.004
0.42
4.71
1.27
0.19
0.12
1.86
0.09
0.05
0.28
0.67
0.74
0.20
0.77
0.27
0.09
0.01
0.01
0.13
0.01
2.18
4.55
0.20
3.19
1.43
0.02
0.16
0.05
0.66
0.10
0.25
0.89
0.14
0.25
0.01
0.19
0.09
0.002
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