Afield experiment on stages of change for smoking cessation: the effects of matched and mismatched information

Behaviour change can be described as a process in which people progress through several qualitatively different stages. Stage models predict that people in different stages need different types of information to progress to subsequent stages. In a field experiment we tested this assumption using the Social Cognitive Stage Model (SCSM). Smokers and ex-smokers in five stages received information in three information conditions: information developed to increase positive outcome expectations of quitting or information developed to decrease the positive outcome expectations of smoking or information developed to increase self-efficacy expectations. Two months after participants were provided with the information, the interaction between stage and information condition was significant. In addition, the match-mismatch test in which the matched conditions are compared with the mismatched conditions was also significant. After eight month, the overall match-mismatch test was still significant, although the expected effects within stages were present only in the precontemplation and in the action stage. Gender interacted significantly with matching: especially after eight months the matching effects were present only in men. The results provide scarce evidence on the validity of stage models in general and more specifically on the validity of the SCSM. In a sample that was very similar to staged samples studied before, we showed that people in different stages benefited from different types of information. This implicates that the stages differ qualitatively. In addition, while most descriptions of people in different stages are based on cross-sectional findings, these experimental data give a new perspective on the psychological characteristics of people in different stages