reinforcement

    You may have read that scientists use rats to study how people learn ( and unlearn ) things. A rat will press a lever to get food, for example. The food is a reward, or a form of reinforcement, meaning that the rat is  more likely to repeat the behavior. The food reinforces the act of pressing the lever. It is no longer an act of idle curiosity but has been rewarded--this is called positive reinforcement. The behavior reinforced in this way will be repeated, and may become a habit.
     Punishment, scientifically,  is another kind of reinforcement--called negative reinforcement. In some ways it makes it more likely that a  behavior pattern or action will be repeated. The negative reinforcement establishes a strong mental connection to the behavior, making it more difficult to forget.
     Scientists have also used rats to study how habits can be broken. Habits which have been formed through positive reinforcement ( rewards ) can be relatively easy to alter--called extinguish by psychologists. When the reward stops, the behavior usually stops fairly quickly.  Habits which have been formed through negative reinforcement ( punishment ) may stop nearly as easily. When the punishment stops, the behavior or habit stops soon after. 
    The hardest habits to extinguish are habits that were formed through off-and-on or intermittent reinforcement. When behavior was rewarded only once in a while, the rats with "habits" tended to keep trying longest before giving up the habit--even after the rewards stopped altogether.
    All of this happens in a laboratory, in a situation controlled by the scientists. In real life, behavior is sometimes punished and rewarded. Or rewarded unintentionally, until it becomes a habit. Real life is not as simple as a laboratory.