Effect of signal word and source attribution on judgments of warning credibility and compliance likelihood

Social-communication models frequently include message source as an importa nt factor in persuasion. However, research on the contribution of source ch aracteristics to warning effectiveness is virtually non-existent. The prese nt research involved two experiments. Experiment 1 examined the effects of the presence (vs. absence) of the signal word WARNING, supplementing it wit h the source-related term GOVERNMENT to the signal word, and the addition o f more specific terms (i.e., US and FEDERAL) on ratings of credibility and compliance likelihood for alcohol, cigarette, and iron supplement warnings. Higher ratings were produced with the signal word's presence than its abse nce and adding more specificity land length) to the source. The highest rat ings accompanied the longest, most specific prefix: US FEDERAL GOVERNMENT W ARNING. Experiment 2 investigated three types of sources on credibility and compliance likelihood: (1) specific regulatory governmental agencies (e.g. , US FOOD AND DRUG ADMINISTRATION), (2) specific scientific professional gr oups (e.g., AMERICAN MEDICAL ASSOCIATION), and (3) general statements in wh ich an explicit source is not mentioned (e.g., Important Health Warning). T he inclusion of specific sources produced higher ratings compared to a sign al word (WARNING) alone. Implications for warning design and further resear ch are discussed.