Narcissists may seem to love themselves, but a new study finds that narcissistic self-aggrandizement may hide deep feelings of inferiority.

According to the new research, people who are narcissistic are likely to tell psychologists that they feel good about themselves. But when the psychologists trick these narcissists into thinking they’re hooked up to a working lie-detector test, the truth comes out and the narcissists admit to lower self-esteem.