[A quote from “How God changes your brain” by Andrew Newberg, M.D. and Mark Robert Waldman BallantineBooks.com Page 141]
Unfortunately, as far as the brain is concerned, negative speech has a stronger effect than positive speech. Negative remarks and memories are more strongly encoded in the brain, and they are the most difficult memories to eradicate. In fact, simply being around negative people will make you more prejudiced, because listening to negative opinions can easily undermine your positive opinions about virtually anything. In essence, our brains are designed to mimic the emotional expressions of others. Not only does this allow us to feel what others feel but it causes what is known as “emotional contagion,” a universal neurological process whereby subjective feelings are transferred to other people and spread through social groups. So how fast does it take the brain to react to another person’s emotion? When you see an angry expression, it takes less than one second for the brain to respond with fear.