Hooked: How to Build Habit-Forming Products

by Nir Eyal

E-mail, for example, utilizes all three variable reward types. What subconsciously compels us to check our e-mail? First, there is uncertainty concerning who might be sending us a message. We have a social obligation to respond to e-mails and a desire to be seen as agreeable (rewards of the tribe). We may also be curious about what information is in the e-mail: Perhaps something related to our career or business awaits us? Checking e-mail informs us of opportunities or threats to our material possessions and livelihood (rewards of the hunt). Lastly, e-mail is in itself a task—challenging us to sort, categorize, and act to eliminate unread messages. We are motivated by the uncertain nature of our fluctuating e-mail count and feel compelled to gain control of our in-box (rewards of the self).