Subsequently, he was told that he had failed the test, and that things would go easier on him if he gave them a confession. He complied with the request, virtually assuring a conviction if the case were retried. Exactly why any attorney would be stupid enough to have his client take a polygraph in a criminal case is beyond me. First of all, taking a polygraph is an attempt to prove one s innocence. Once you start trying to prove the negative you are already in trouble.
Some people do well on the tests because they are so sociopathic they can lie without anxiety.
Some do poorly because they are anxious and fearful people by nature. An attorney has to know the psychology of the person he is dealing with. Even then, the wisdom of taking a polygraph is questionable. To take one without counsel present is absurd. Police will often lie to people who have passed the polygraph in an effort to extort a confession, telling them that they failed.