Chris Voss's mirroring technique from Never Split the Difference works by repeating the last few words someone says. A study by psychologist Richard Wiseman found waiters who mirrored customers' orders earned 70% higher tips than those using positive reinforcement.
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This is the Jedi mind trick that Chris Voss put in his book Never Split the Difference that the FBI uses when negotiating with people. So the concept is called mirroring. Psychologist Richard Wiseman created a study using waiters to identify what was the more effective method of creating a connection with strangers— mirroring or positive reinforcement. One group of waiters using positive reinforcement lavished praise and encouragement on patrons using words such as great, No problem, sure, in response to each other. The other group of waiters mirrored their customers simply by repeating their orders back to them. The results were stunning. The average tip of the waiters who mirrored was 70% more than those who used positive reinforcement. In the FBI, mirroring is repeating back the key 1 to 3 words at the end of the previous person's sentence.