In the relapse prevention model, urges and cravings are thought to be caused by psychological or environmental stimuli. A person may be conditioned to experience an urge or craving when exposed to a stimuli which is associated with previous gratification. Alternatively, certain cognitive processes associated with previous gratification may lead to an urge or craving (such as remembering the positive effects of alcohol use). In both cases, these processes may increase the individual's vulnerability to high-risk situations, which may lead to relapse.