e., “red” printed in red ink) and incongruent stimuli (i.e., “green” in red ink) and measures interference between cognitive processes by requiring the participant to name the color (“red”) regardless of the word (“red” or “green”; Stroop 1935). It is hypothesized that the slower the speed of color-naming during incongruent stimuli, the more important the cognitive interference component. Consequently, in the Drug Stroop, the slower the speed of color-naming during stimuli associated with drug cues, the stronger the attentional bias toward

the drug-related stimuli (Cox et al. 2006). Inhibitors,research,lifescience,medical For example, 24-h abstinent smokers showed higher attentional bias for smoking cues than current smokers (Waters and Feyerabend 2000). The Dot Probe task also measures attentional bias toward drug-related stimuli. Here, two stimuli (one drug-related and one neutral) are presented side by side, after which Inhibitors,research,lifescience,medical the images disappear and a dot appears for a short time. Fast responding toward the dot where a drug-related stimulus was previously shown is a measure for increased attentional bias. Smokers showed Inhibitors,research,lifescience,medical greater attentional bias toward smoking-cues than nonsmokers during a Dot Probe task (Ehrman et al. 2002). In addition, compared with current smokers, 12-h abstinent smokers showed increased attentional bias for smoking cues (Gross et al. 1993),

and ex-smokers showed an intermediate level of attentional bias compared with current smokers and nonsmokers measured with the Dot Probe task (Ehrman et al. 2002). Using a related measure, abstinent crack-cocaine dependent patients had faster eye-movements toward cocaine-related pictures Inhibitors,research,lifescience,medical as compared to neutral pictures, Inhibitors,research,lifescience,medical and this correlated with self-reported intensity of cocaine craving (Rosse et al. 1997). It should

be noted that the drug Stroop and the Dot Probe task both measure selective attention (i.e., to drug stimuli), but the Stroop task requires more cognitive effort and flexibility, which might be responsible for PFT�� order different findings when using these different first paradigms. Cue-reactivity is also an import aspect of drug addiction and refers to the physiological and related subjective reactions (craving) that occur in the presence of drug-related stimuli, and can ultimately lead to relapse. Cue-reactivity is generally investigated using a cue-exposure or cue-reactivity task. Unlike other neurocognitive tasks, cue-reactivity paradigms employed during functional imaging only require the participant to watch drug-related pictures or videos (without any cognitive effort), although some cue-reactivity tasks include easy binary tasks to control for attention differences, in which baseline trials are usually incorporated requiring similar motor responses.