Effects of endorser type and testimonials in direct-to-consumer prescription drug advertising (DTCA)

This study aims to examine the effects of different types of endorsers (expert vs consumer vs celebrity) in testimonial vs non-testimonial message contexts on consumers’ responses toward direct-to-consumer advertising (DTCA).

An online experiment was conducted with a 3 (endorser type: expert vs consumer vs celebrity) × 2 (message type: testimonial vs non-testimonial) plus control group (no endorser, no testimonial) factorial design to assess the various dependent variables.

Perceived source credibility and similarity was significantly different across the endorser types, and the expert endorser (i.e. a doctor) generated the highest mean level of source credibility, while consumer endorsers generate the highest mean source similarity. The interaction of endorser type and message type significantly impacted ad believability and skepticism. Specifically, the endorser type factor had a significant impact on the dependent variables only in the testimonial ad condition, but not in the non-testimonial ad condition. The effects were mediated by source credibility.

While the focused results show celebrities may not be the strongest choice to endorse when using testimonials, the overall lack of main effect of testimonials lends to the possibility of a plateauing of effects with the various appeals used in DTC ads. DTCA has now been around for over 20 years, and this study lends to the possibility consumers are becoming unaffected by the various appeals used by pharmaceutical manufactures and only respond when a multitude of personally relevant factors are in place.