What is the "Gilbert Experiment" as noted in the nonfiction book, Thinking, Fast and Slow?

Psychologist Daniel Gilbert developed a theory of believing and not-believing. It was his belief that in order to understand something, an individual must first be willing to believe it. In other words, the skeptical mind will not listen to a presentation of facts or beliefs. His System 2 thinking will be busy formulating reasons why what he is being told is bogus. Gilbert felt that belief was essential in understanding. Without this understanding it would be impossible to make a judgment as to whether the information was believable. After this initial stage and there is a level of understanding of the subject at hand, the person can then chose to “unbelieve” it.