““Facebook provides numerous examples of variable social rewards. Logging-in reveals an endless stream of content friends have shared, comments from others, and running tallies of how many people have “liked” something (figure 21). The uncertainty of what users will find each time they visit the site creates the intrigue needed to pull them back again. While variable content gets users to keep searching for interesting tidbits in their Newsfeeds, a click of the “Like” button provides a variable reward for the content’s creators. “Likes” and comments offer tribal validation for those who shared the content, and provide variable rewards that motivate them to continue posting.””