A seller using a positive customer review or testimonial to encourage other potential customers is an example of which stimulus-response influence principle?

• A. Social proof
• B. Commitment and consistency
• C. Scarcity
• D. Authority

Answer: (A)

Using a positive customer review or testimonial taps into social proof—the tendency to look to others when deciding what to do, especially when information is uncertain. Seeing real buyers share their satisfaction acts as third-party validation, signaling that the product delivers value and is worth trying. This reduces the perceived risk for a potential buyer and makes the decision feel safer, because if others like it, it’s likely to meet their needs too.

It’s not about an authority vouching for the product, which would be authority endorsements; it’s about the crowd of fellow customers influencing the decision. It also isn’t about commitment and consistency, which would require a prior, smaller pledge influencing later behavior, nor about scarcity, which hinges on limited availability to create urgency. Testimonials exploit the power of social proof to persuade by leveraging the buyers’ shared experiences.