" An example: A few years ago, the public health authorities in Canada, where it had been estimated that smoking kills forty-five thousand people a year, decided to supplement the warning printed on every pack of cigarettes with a shock-photograph—of cancerous lungs, or a stroke-clotted brain, or a damaged heart, or a bloody mouth in acute periodontal distress. A pack with such a picture accompanying the warning about the deleterious effects of smoking would be sixty times more likely to inspire smokers to quit, a research study had somehow calculated, than a pack with only the verbal warning. Let’s assume this is true. But one might wonder, for how long? Does shock have term limits? Right now the smokers of Canada are recoiling in disgust, if they do look at these pictures. Will those still smoking five years from now still be upset? Shock can become familiar. Shock can wear off. Even if it doesn’t, one can not look. People have means to defend themselves against what is upsetting—in this instance, unpleasant information for those wishing to continue to smoke. This seems normal, that is, adaptive. As one can become habituated to horror in real life, one can become habituated to the horror of certain images. "
― Susan Sontag , Regarding the Pain of Others