For many persistent nail-biters, the unconscious trigger is the unpleasant feeling of stress. The more the biter associates the act of nail chomping with the temporary relief it provides, the harder it becomes to change the conditioned response. Like nail biting, many of our daily decisions are made simply because that was the way we have found resolution in the past. The brain automatically deduces that if the decision was a good one yesterday, then it is a safe bet again today and the action becomes a routine.
