Objective: There is strong evidence showing that pictorial health warnings are more effective than text-only warnings. However, much of this evidence comes from high-income countries and is limited to cigarette packaging. Moreover, few studies have identified mechanisms that might explain the impact of warnings.
Methods: The current study examined the potential mediating role of negative affect and the moderating influence of message credibility in perceived effectiveness of smokeless tobacco warnings in two low- and middle-income countries (LMICs). Field interviews were conducted in India and Bangladesh, with adult (19+ years) smokeless tobacco users (n=1053), and youth (16-18years) users (n=304) and non-users (n=687). Respondents were randomly assigned to view warnings in one of four conditions: (1) Text-only, (2) pictorial with symbolic imagery, (3) pictorial with graphic images of health effects, or (4) pictorial with personalized graphic images plus a personal testimonial.
Results: The findings provide support for the mediating influence of negative affect in perceived effectiveness, for adult and youth smokeless tobacco users who viewed pictorial warnings (vs. text-only), and graphic health warnings (vs. personal testimonials). Among adults, message credibility moderated the indirect effect; the association was stronger when credibility was high and weaker when it was low. Among youth users and non-users, message credibility did not moderate the indirect effect.
Conclusions: Consistent with research from high-income countries, these findings highlight the importance of selecting imagery that will elicit negative emotional reactions and be perceived as credible. Differential effects among adults and youth highlight the importance of pre-testing images.
Keywords: Health warnings; Low and middle income countries; Message credibility; Negative affect; Smokeless tobacco.
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