Today's Science Times has an article by Benedict Carey about why unwanted or rude impulses seemingly arise at the worst possible times:
Perverse impulses seem to arise when people focus intensely on avoiding specific errors or taboos. The theory is straightforward: to avoid blurting out that a colleague is a raging hypocrite, the brain must first imagine just that; the very presence of that catastrophic insult, in turn, increases the odds that the brain will spit it out.
One cannot perform a negative task. There is no such thing (for the brain) as not thinking about something or not eating that chocolate cake, or not looking at the little spit bubbles collecting in the corner of the mouth of the person interviewing you for an important job. This brings up one of my favorite misunderstandings about the brain. The brain produces thought, but its processes are not thought-like, they are computational. As an acting teacher it has long been evident to me that, if one want to perform a negative action one has to translate it into a positive one.
Soccer players told to shoot a penalty kick anywhere but at a certain spot of the net, like the lower right corner, look at that spot more often than any other.To not kick the ball to the lower right corner of the net has no meaning for the brain. What one can do is aim with extraordinary concentration and extraordinary interest for the upper left corner. To not think about the white elephant one must think of something infinitely more compelling to us than that elephant. In fact, I think one of the chief ingredients of great talent involves these 3 feats - learning how to translate useless instructions (fears of failure, negative criticism, performing impossible tasks...) into things we can do, knowing oneself well enough to know which doable tasks are the most compelling to us, and long practice at performing these tasks relentlessly no matter what else passes through our minds. The most talented sports players, artists and surgeons know how to re-direct themselves relentlessly.