Another fantasy I sometimes indulge (is this a revelation?) is when I see an attractive female and imagine approaching and kissing her (or other activities). Do I do this? . . NO. I'm not even one to approach females in a nightclub situation . . just a bit too timid and insecure, I guess. I am definitely not the "predator" that Feminists tend to want to portray males as. If anything, if I hook up its because the woman took the initiative (i.e., my present gf).
But, given my fantasy example, former U.S. President Jimmy Carter would say that I not only "lusted in my heart", but the fact that I had these thoughts is the same as if I carried out the actions of my fantasy. If I went over to this woman and took her into my arms and kissed her . . that could be construed as assualt, even rape. Isn't that different from just THINKING something and NOT DOING it? I think so. With all due respect to former Pres. Carter, I think he's all wet on that point. Thoughts and acts are NOT the same. Nothing changes if all one does is think about doing something . . . what counts is one's actual behavior.
Yet, we have these misconceptions in society that, "If you think of striking someone, its the same as actually striking them," or "If you think of having sex with a woman, that is the same as rape" (assuming the woman does not even know you and would be unlikely to consent to the actual act). But, I think the two things -- thoughts vs. actions -- make a world of difference. Imagine how life today would be different if those airline hijackers had simply imagined flying jets into buildings in America . . vs. actually doing it. Imagine that.
Thus, I disagree with your premise that exposure to ideas leads to actions. I think it depends upon the individual, and I have faith that most people can handle seeing acts of sex or violence without going out and becoming muggers or rapists (but defense attornies trying to excuse violent acts by their clients would love to have you two guys on the jury, buying the defense).