Facebook’s single most momentous innovation in behavioral engineering is the now equally ubiquitous “Like” button, adopted in 2009. According to contemporaneous blog posts by longtime Facebook executive Andrew Bosworth, the “Like” button had been debated internally for more than a year and a half before Zuckerberg’s final decision to incorporate it. He had rejected the idea more than once, fearing that it would detract from other features intended to lift monetization, such as the controversial Beacon program. Significantly, the founder embraced the button only when new data revealed it as a powerful source of behavioral surplus that helped to ratchet up the magnetism of the Facebook News Feed, as measured by the volume of comments.

Shoshana Zuboff, The Age of Surveillance Cap…, loc. 1456