This interaction effect showed to be not significant (IRR = 0.70, 95% CI = 0.35–1.38, p = 0.301). This study is the first to show the importance of passive (imitation)

peer influence VX770 over and above the impact of active (pressure) peer influence on young adult smoking in an experimental design. In our study, peer smoking increased significantly young adults’ likelihood to smoke more cigarettes while peer pressure did not. In the literature, peer smoking is suggested to tap into the passive peer influence, and the underlying mechanism in experimental studies and survey studies on smoking is often contributed to imitation. Students confronted with smoking peers are more likely to smoke regardless of being offered a cigarette or not: seeing is doing. Several theoretical models may explain the underlying mechanisms leading to imitation of behavior of others. One of these theories that have frequently been examined in previous studies is social conformity (see also a meta-analysis of Bond and Smith, 1996). Solomon Asch’s

work showed that in a group setting participants conform to the norm of the group, i.e., they tended to conform to the behavior of the other group members (Asch, 1951). Thus, social conformity may explain our findings and imply that young adults imitating peer smoking have been intentional. However, in our study we tested peer dyads and not peer groups. There is evidence that conformity of people is more likely to occur in groups than in dyads, and thus this explanation may have played a minor role in our present study. Another SB203580 molecular weight possible explanation is that imitating the other in human interaction may reflect a basic instinct in human beings that might even be biological in origin, as has been shown by studies on the importance of imitation for social interaction and social

development of animals (Hurley and Chater, 2005). An alternative theory to explain our findings is the cue-reactivity paradigm. According to this paradigm, smokers react to smoking-related mafosfamide cues/stimuli (e.g., handling a lit cigarette, ashtrays, lighters, or smelling another person’s cigarette) in their environment by an increase in craving to smoke (see also meta-analyses of Carter and Tiffany, 1999 and Conklin et al., 2008). The smoking-related cues of ashtrays, lighters and package of cigarettes were present in all four conditions, although handling a lit cigarette and smelling another person’s cigarette were only present in the condition were the confederate smoked. Thus, these latter two smoking-related cues may have elicited craving in the daily smoking young adults and triggered them to smoke. However, in our previous experimental study (Harakeh and Vollebergh, in press) we excluded in our research design the alternative hypothesis concerning smelling another person’s cigarette smoke. These findings showed that when the participant interacted with a smoking peer through the internet and webcam (i.e.