The theory of cognitive harmony, initiated by Fritz Heider in 1958, proposes that a person’s thoughts and feelings are interconnected and that the stability of attitudes depends on the balance between these elements. According to this theory, individuals constantly strive to maintain a certain mental coherence and harmony. This theory highlights a specific configuration called a triad, involving an observer, an object, and another person, where the observer’s attitudes toward the object and the other person can be positive or negative. Similarly, the observer’s perceived relationship between the object and the other person can be judged as favorable or unfavorable.

This approach is often applied in the field of advertising, particularly in testimonials where a celebrity or expert acts as a mediator. For example, the famous cyclist Chris Hoy can play this mediator role, subtly using British humor to sidestep the commercial aspect of his testimonial.