This week's theory is useful when considering how often our characters wind up in some sort of group situation in which they are advocating for one position over another. In romance, the hero and heroine will usually be on opposite sides of the fence, and this theory will help you be bold and confident in developing your plots and upping the ante.
So imagine it. Your heroine goes toe-to-toe with the hero in a conference room about an issue and hears herself saying something she never intended to say that's above and beyond what she had intended. Now she's obliged to stick by her position, even if she think it's a bit over the top.
For those who write YA, groups of young people perhaps make some of the stupidest decisions ever. Often, they'll regret these decisions later, but because of the group polarization that this happens (and even the immature idea that one side has to one-up the other or risk not being cool).
And another interesting fact is that people who tend to grab life by the horns and thrive on risk will make even riskier decisions in a group because some of the responsibility of the risk is shared. Vice versa for people who are conservative. In a group, they will make ultraconservative decisions that even they think are extreme. Just FYI.
You might want to consider having a voice of reason for the character if they do get too risky or too extreme. A nice elderly neighbor or post office worker or barber will do just fine. Someone who will speak the truth to them through unbiased eyes will turn the plot around toward the end to bring about resolution.