Humphrey's 2nd Law, also known as the Law of Congruence, is a principle in communication that states that people are more likely to believe and accept a message when the words, tone of voice, and body language are congruent or consistent with each other.
In other words, when there is a match between what is being said, how it is being said, and the speaker's nonverbal behavior, the message is perceived as more authentic, credible, and trustworthy. Conversely, when there is a mismatch or incongruence between these elements, the message is perceived as less believable and may be met with suspicion or skepticism.
Humphrey's 2nd Law has important implications for effective communication, particularly in contexts such as public speaking, sales, and interpersonal interactions. To maximize the impact and credibility of a message, speakers should ensure that their words, tone, and body language are in alignment and that they are conveying a consistent message. This can help to build trust and rapport with the audience and increase the likelihood that the message will be received and accepted.