[It's existence] has implications for drug addiction and other compulsive behaviors. Berridge has proposed that in some addictions the brain becomes sensitized to the wanting cycle of a particular reward. So addicts become obsessively driven to seek [emphasis added] the reward, even as the reward itself becomes progressively less rewarding once obtained. 'The dopamine system does not have satiety built into it,' Berridge explains. 'And under certain conditions it can lead us to irrational wants, excessive wants we'd be better off without.' So we find ourselves letting one Google search lead to another, while often feeling the information is not vital and knowing we should stop. 'As long as you sit there, the consumption renews the appetite,' he explains.Not only can this seeking center lead us to endless hours on Google, email, blogs, twitter, etc. it can also explain why it's "hard to stop at just one," why flirting, sexual foreplay, and new sexual conquests are enjoyable. (It's not the conquest; it's the quest.) Taken to certain extremes (as in the addiction example mentioned) it also explains the pleasure in bondage and anorexia. And it explains why we are so fascinated with quest stories. Anticipation when drawn out the right way is almost irresistible. Although not always (as some of the examples above illustrate) it's often relatively harmless—although frequently a time waster.
See also, Berridge's website.