For the in vivo smoking exposure, participants were presented with their cigarette box, asked to remove one cigarette, and hold it for 90 s (unlit). For the neutral cue, they were presented www.selleckchem.com/products/Gemcitabine-Hydrochloride(Gemzar).html with a stapler and asked to hold it for the same amount of time. Expected cigarette cravings were measured immediately before each cue induction, and actual cigarette cravings were measured immediately following each cue. For the assessment of expected cravings, participants were described the cues they were about to encounter and told to rate how much they expected to crave cigarettes following exposure to the cues (e.g., How would you expect to feel when asked to imagine smoking a cigarette?).
To avoid possible carryover effects (Heishman, Lee, Taylor, & Singleton, 2010; Sayette, Griffin, & Sayers, 2010) within exposure modality (imaginal/in vivo), on each day, participants were exposed to the neutral cue first, followed by the smoking cue. In addition, participants viewed a nature video for 3 min between each presentation to provide a rest and facilitate a return to baseline. Upon completion of the study, participants were thanked for their participation, offered referrals for smoking cessation interventions, and paid an honorarium for their time. Data Analysis In the first set of analyses, we aimed to characterize the relationship between expected and actual cravings. To that end, we performed a three-way repeated measures analysis of variance (ANOVA), including (a) neutral versus smoking cues, (b) imaginal versus in vivo cues, and (c) expected versus actual cravings, as within subjects�� factors and evaluated differences between actual and expected craving levels as the dependent variables.
Next, we performed zero-order Pearson correlations between expected and actual cravings in response to the smoking cues as well as partial correlations that controlled for expected and actual cravings in response to the neutral cues. To address the primary hypothesis that cravings would be related to cessation outcomes, we performed a series of regression analyses, with quit duration and perceived quit difficulty as dependent variables and expected and actual cravings as the independent variables. Demographic and smoking-related variables were tested for possible relationships with dependent variables and if related, were included as covariates.
Because the quit duration data were not normally distributed, an iterative Box�CCox transformation procedure was employed to identify the best transform (Box & Cox, 1964), and regression analyses were performed on the transformed values. The transformation was highly effective, reducing skewness from 4.13 to 0.91 and kurtosis from 18.02 to 1.11. The perceived quit difficulty data Carfilzomib did not depart significantly from normality and were thus not transformed.