Addiction can be viewed as a learned behaviour because the positive reinforcement (e.g. pleasure and enjoyment) gained from a behaviour such as smoking makes it more likely that the individual will repeat the behaviour in the future. In terms of smoking, learning operates during the initiation phase (when the person first starts smoking); the maintenance phase (where they become a habitual smoker); and the relapse phase (where they try to give up, but learned associations with pleasure make it very difficult). Initiation: Social learning theory suggests that young people observe and imitate role models (parents and peers) around them who smoke and vicarious reinforcement leads them to expect positive consequences from smoking. In addition, the principles of operant conditioning suggest that any behaviours that are rewarded will increase in frequency. Addictive substances like nicotine are immediately rewarding because they activate areas of the brain that regulate feelings of pleasure, which results in quick learning. Maintenance: negative reinforcement can help explain the maintenance of an smoking in terms of withdrawal symptoms. As the effects of nicotine wears off, symptoms such as increased anxiety, irritability or low mood may be experienced. The person is then likely to smoke a cigarette to remove these symptoms (negative reinforcement) and as a result they are likely to repeat this behaviour in the future. Relapse: Cue reactivity is a learning explanation that can be used to explain relapse. This is because the person associates specific moods, situations or environmental factors (smoking-related cues) with the rewarding effects of nicotine, and these cues can trigger a relapse.