Messenger effect
The same message persuades differently depending on who says it.
What it means
The principle that people are heavily influenced by the characteristics of whoever conveys information — their authority, status, similarity, likability, and attractiveness — often independent of the content itself. It generalizes source credibility to include 'soft' cues like demographic match and warmth, which determine whether an audience tunes in or tunes out. As the first lever in the MINDSPACE framework, it is a practical entry point for behavioral interventions: change the messenger and uptake can shift sharply. It matters because choosing the right spokesperson can outweigh refining the words.
Examples
Patients are likelier to follow advice delivered by a peer who shares their background than by a distant expert.
A safety warning delivered by a shift supervisor who has done the job for twenty years gets acted on; the identical wording emailed from head office is skimmed and forgotten.
A bank's fraud alert is heeded when it comes from a named local branch manager, while the same text signed 'Customer Security Team' is dismissed as another scam message.
First described in MINDSPACE framework, Dolan et al. (2010); rooted in Cialdini's work.