Found : Where perverse impulses and urges come from

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.

“We know that what’s accessible in our minds can exert an influence on judgment and behavior simply because it’s there, it’s floating on the surface of consciousness,” said Jamie Arndt, a psychologist at the University of Missouri.