Tammy Billups is the one person who made sure the woman in the park was safe. In these types of scenarios, John says, it is almost always women who stop to help.

"I didn't see a choice," Tammy says. "In my mind, it was something I had to do."

After Tammy learned the fight between the couple was a staged experiment, she wrote an e-mail to Oprah explaining her decision to intervene. "I've come to realize that when I don't walk through my fears to do what I believe is the right thing, I actually feel worse because I will beat myself up about it for days, weeks, maybe longer," Tammy wrote. "When I am able to face my fears, I feel better about not only myself but the outcome of the action."