Psychological dependence is a form of dependence that involves emotional–motivational
withdrawal symptoms (e.g.,
a state of unease or dissatisfaction,
a reduced capacity to experience pleasure, or
anxiety) upon cessation of drug use or engagement in certain behaviors. Physical and psychological dependence are sometimes classified as a facet or component of
addiction, such as in the
DSM-IV-TR; however, some drugs which produce dependence syndromes do not produce
addiction, and vice versa, in humans. Addiction and psychological dependence are both mediated through psychological
reinforcement, a form of
operant conditioning, but are associated with different forms of reinforcement. Addiction is a compulsion for rewarding stimuli that is mediated through
positive reinforcement. Psychological dependence, which is mediated through
negative reinforcement, involves a desire to use a drug or perform a behavior to avoid the unpleasant withdrawal syndrome that results from cessation of exposure to it.