Severity and susceptibility: Measuring the perceived effectiveness and believability of tobacco health warnings

Background: Pictorial tobacco health warning labels (HWLs) have been shown to be more effective than text-only HWLs in changing smoking attitudes and intentions. However, there is contradictory evidence regarding how the severity of the content of HWLs influences responses to them. Methods: We examined the perceived believability and effectiveness of HWLs in an online study using a convenience sample of non-smokers (N = 437) and smokers (N = 436). HWLs were in one of three presentation formats: (text-only, a moderately severe image or highly severe image) and focussed on three disease outcomes (lung cancer, blindness or tooth and gum disease). Participants rated the effectiveness and believability of each HWL and also rated their perceived susceptibility to each disease. Results: A 2 (smoking status) × 3 (presentation format) × 3 (disease outcome) ANOVA was run for both believability and effectiveness ratings. The most severe pictorial HWLs received the highest believability and effectiveness ratings and as expected, the text-only HWLs received the lowest. Lung cancer HWLs were rated most believable and effective, with the blindness HWLs receiving the lowest scores. A 2 (smoking status) × 3 (disease outcome) ANOVA was conducted on the ratings of perceived susceptibility to the three diseases. Smokers considered themselves to be more susceptible to all three diseases, and among smokers, perceived susceptibility to the diseases was positively correlated with effectiveness and believability ratings of the HWLs. Conclusion: Our findings support previous evidence that pictorial HWLs are rated as more effective and believable than text-only warnings, and provide some support for the use of severe or 'grotesque' HWLs on tobacco products. Our data also suggest that HWLs should aim to increase perceived susceptibility to disease, as this was positively related to perceived message effectiveness and believability.