Humans, like the mice in Skinner’s box, crave predictability and struggle to find patterns, even when none exist. Variability is the brain’s cognitive nemesis and our minds make deduction of cause and effect a priority over other functions like self-control and moderation.

Recent neuroscience has revealed that our dopamine system works not to provide us with rewards for our efforts, but to keep us searching by inducing a semi-stressful response we call desire.

Email, for example, is addictive because it provides all three reward types at random intervals. First, we have a social obligation to answer our emails (the tribe). We are also conditioned to know that an email may tell us information about a potential business opportunity (the hunt). And finally, our email seems to call for us to complete the task of removing the unopened item notification in a sort of challenge to gain control over it (the self). Interestingly, these motivations go away as soon as we’ve actually opened all our emails and the mystery disappears. We’re addicted to checking email while there is still variability of reward and once that’s gone, emails languish in our inboxes.

We’re meant to be part of a tribe so our brains seek out rewards that make us feel accepted, important, attractive, and included.

But as sociable as we are, our individual need for sustenance is even more crucial. The need to acquire physical things, such as food and supplies, is part of the brain’s operating system and we clearly wouldn’t have survived the millennia without this impulse. But where we once hunted for food, today we hunt for deals and information. The same compulsion that kept us searching for food coerces us to open emails from Groupon and Appsumo. New shopping startups make the hunt for products entertaining by introducing variability to what the user may find next. Pinterest and Wanelo keep users searching with an endless supply of eye candy, a trove of dopamine flooding desirables. To see an example of how the hunt for information engages users, look no further then the right side of this page. There, you will find a listing of popular posts. Using intriguing images and short, attention-grabbing text, the list is a variable reward mechanism designed to keep you hunting for your next discovery.

We also seek mastery of the world around us. Game mechanics, found everywhere from Zynga games to business productivity apps like to-do lists, provide a variable rewards system built around our need to control, dominate, and complete challenges. Slaying new messages in your inbox stimulates neurons similar to those stimulated by playing StarCraft.

Variable rewards come in three types and involve the persistent pursuit of: rewards of the tribe, rewards of the hunt, and rewards of the self.

As B.F. Skinner discovered over 50 years ago, variable rewards are a powerful inducement to creating compulsions.

All of us writers at ReadWriteWeb participate in varying degrees on Twitter too. We post and repost links to our stories and that of our colleagues, and many people follow us as a result. All well and good. But wouldn't it be better if someone else posts a link to our stories on their Twitter account? Doesn't that link carry more weight than just our own flogging of our content? Yes.

you have to constantly feed your discussions and other sites with content, with recommendations, and spend time to make sure that you are part of the ongoing conversations online. It certainly is easier to just put up a piece of content on your own website, press publish, and walk away. But it is more satisfying once you get your OPM network working for you.