A journalist had a quirky habit of not using blue pens. So when his colleague asked him if he needed anything from the store, he asked for some pens. “But not blue pens,” he said. “I don’t want blue pens. I don’t like blue. Blue is too heavy. So please purchase 12 ballpoint pens for me—anything but blue!” The next day his colleague passed him the pens—and they were all blue. When asked to explain, he said, “You kept saying ‘blue, blue.’ That’s the word that left the deepest impression!” The journalist’s use of repetition had an effect, but not…