Much of what they discovered validated Peretti's original theories—particularly about the necessity of stimulating "pleasure in the social process of passing" something along and of ensuring that the contagion "represent[s] the simplest form of an idea." But the "pleasure" of sharing did not necessarily mean that viewing the content had been pleasurable. The urge to share was activated by a spectrum of "high-arousal" emotions, like awe, outrage, and anxiety.

Tim Wu, The Attention Merchants, loc. 1070