Table 1.

Characteristics of Included Studies (n = 6).

Study	Study Design	Sample Size	Types of Sample	Demographics of Sample	Country	Diagnosis of Sample	Method of Diagnosis	Attention Bias Method	Outcomes
Franken, I.H. et al. (2000) [17]	Randomised trial	21 heroin-dependent participants 30 control participants	Participants with heroin dependence were recruited from an inpatient treatment centre Participants in the control group were recruited among clinical and administrative staff in the clinic	71.4% males (heroin-dependent) 83.3% (control group) Mean age 31.5 years (heroin-dependent) Mean age 34.8 (control group) Mean self-reported duration of heroin dependence was 93.9 months	Netherlands	Heroin Dependence	Based on the DSM-IV criteria for heroin dependence	Drug Stroop task	Higher overall reaction time for heroin participants as compared to control participants Mean pre-experimental craving was 13.8, mean post masked Stroop was 7.19 and mean post unmasked Stroop was 15.2
Lubman, D.I. et al. (2000) [18]	Randomised trial	16 methadone-maintained opiate addicts 16 age-matched control	Heroin addicts were recruited from local drug services Staff from these services were recruited as controls	Opiate group: mean age 31.4, Male to Female 11:5 Control group: mean age 31.7, male to female 8:8	United Kingdom	Heroin Dependence	ICD-10 and DSM IV	Pictorial Probe Detection Task	Faster reaction times to probes that replaced drug stimuli, indicative of the presence of an attentional bias
Marissen, M. et al. (2006) [19]	Randomised trial	110 Participants assigned to either cue exposure therapy or placebo psychotherapy	Abstinent heroin addicts who were admitted voluntarily to an in-patient drug-free therapeutic centre in the Hague	89% males, mean age 34 years old Average age of onset of heroin usage was 21.4 years, most have used heroin for 9.3 years	Netherlands	Heroin Dependence	DSM-IV criteria for heroin dependence	Emotional Stroop Task	Pre-treatment attentional bias predicted relapse at three months follow-up Reduction of attentional biases in both experimental conditions
Montgomery et al. (2010) [20]	Randomised trial	32 regular cocaine users and 40 non-users	Student Population at Liverpool John Moores University and the general population in the surrounding areas	Mean age for cocaine users assigned to placebo 19.29, assigned to alcohol 20.23 Mean age for non-users assigned to placebo 19.59, assigned to alcohol 20.0 13 male in cocaine use group 19 male in non-cocaine use group	United Kingdom	Cocaine dependence	Questionnaire	Visual Probe and Modified Stroop task	Cocaine participants who received alcohol had increased attentional bias for cocaine pictures The cocaine Stroop revealed no differences between cocaine users and non-users, and no effects of alcohol in either group
Mayer, A.R. et al. (2016) [21]	Randomised trial	37 participants assigned to either attentional bias modification therapy (ABMT) or control therapy	Not mentioned	ABMT group: 14 male, and 5 female, mean age 37.4 Control group: 10 male and 8 female, mean age 38.9	United States	Cocaine dependence	Structured clinical interview for DSM-IV	Visual Probe task	Presence of attentional bias Attentional bias not subjected to modification by ABMT
DeVito, E.E. (2017) [22]	Randomised trial	38 in treatment as usual plus computer-based CBT (CBT4CBT) 41 in treatment as usual	Recruited from community-based outpatient clinic	46% female, mean age 42.2	United States	Cocaine use disorder	DSM-IV	Computerized drug Stroop test	Stroop testing revealed that participants who have had a longer duration of cocaine abstinence during treatment (3+ weeks) have greater reductions in Drug Stroop effect. Engagement with CBT4CBT intervention also led to a reduction in Drug Stroop effect