The defense mechanism that John uses is rationalization. Rationalization is a type of defense mechanism employed when the individual tries to justify his or her actions by giving seemingly logical explanations  or reasons. The individual will use this defense mechanism to deflect guilt or shame. It is apparent from John’s answer that he uses rationalization as a way to justify his lies to his parents by telling them that he’s going to Lisa’s house, even though he’s going to ride around with Pete instead.
