Bored while waiting at the bus stop, Kate sticks a cigarette in her mouth just as she notices a billboard across the road. The small print reads, "Warning: Smoking causes lung cancer, heart disease, emphysema(肺气肿)and may complicate pregnancy." Kate stops for a moment. "How many have I had already today？" she asks herself.
But then she lights up. "I don't smoke that much," she reasons, to quiet her conscience. "And anyway, I exercise and eat pretty well." Every day we wrestle with opposing viewpoints that battle it out in our minds—a tension known as cognitive dissonance. Social psychologist Leon Festinger developed the concept in 1957, from the assumption that human beings fundamentally strive for harmony in their thinking. In the face of contradictory paths, our minds attempt to restore internal peace. We strive for the reconciliation of two conflicting thoughts, even if we must resort to a third to attain it, such as, "Gramps smoked a pack a day, and he lived to be 90."
Since Festinger's time, numerous researchers have shown how we attempt to reduce mental tension. To become truly content, it seems, we should favor smart choices over emotional ones, but even then, we may need to fool ourselves into thinking we have made the right decision.
Imagine you are looking to buy a used car. Two models stand out—a practical little sedan that does not use much gas and a stylish, fuel-guzzling sports car. After a good deal of back and-forth, you decide on the sports car. But as soon as you have driven it off the lot, you get an ill feeling in your stomach. Shouldn't you have purchased the more efficient model？
Consumers call this feeling buyer's remorse. Psychologists call the tension that occurs after such decision making the regret effect. But cognitive salvation comes quickly. "Don't be an idiot, "you tell yourself. "You'd be too cramped driving in that little thing. And the sports car has side air bags. And a CD player." The good features of the chosen car get bumped up in estimation, whereas the bad features of the rejected one get exaggerated. Internal harmony is restored.
Researchers are finding more and more examples of cognitive dissonance.
In 2003 and 2004 studies by Michael I. Norton, now at Harvard Business School, and Monin of Stanford University unveiled a vicarious form. of the phenomenon. In one exercise, students who were waiting to participate in an experiment overheard a staged conversation in which an investigator convinced a student to present an opinion during discussion time that would contradict what he believed: he was to speak in favor of tuition increases. Students who heard the coercion and later were part of the discussion voiced less skepticism about tuition hikes than they had previously. Apparently, the knowledge of their classmate's presumed internal conflict caused cognitive tension in them as well. The easiest way to restore equilibrium was to agree with their friend's stated position.
The potential for artificially inducing such attitudinal change is limited, nonetheless. Social psychologists Fritz Strack and Bertram Gawronski in a 2004 study of social groups found that although we may change our conscious attitudes to justify contradictory behavior, our basic unconscious thoughts and feelings are not easily remolded—even clearly impugned social views such as prejudice.
Why does Kate lit up a cigarette even she notices the billboard？

A. Such diseases as lung cancer, emphysema, does not affect her.
B. She does more exercises and has a better diet than most of smokers.
C. She finds a good excuse to justify her smoking.
D. She smokes less than other smokers.