"Asked to elaborate, Lisak explained, "One of the things that is difficult for most of us, frankly, to understand about a rape, is that there doesn't have to be a gun to the head, there doesn't have to be a knife present, there doesn't have to be a verbalized threat for the act itself to be enormously terrifying and threatening....There is a difference between sexual violence and other forms of assault. Sexual violence is so intimate." When your body is penetrated by another person against your will, Lisak said, it often induces a uniquely powerful kind of terror. According to many peer-reviewed studies, a large percentage of the victims of non-stranger rapes "actually feared they were going to be killed," even when "there was no weapon and no overt violence."