Malcolm Gladwell describes the "three rules of epidemics" (or the three "agents of change") in the tipping points of epidemics.
The Law of the Few
"The Law of the Few", or, as Malcolm Gladwell states, "The success of any kind of social epidemic is heavily dependent on the involvement of people with a particular and rare set of social gifts". According to Malcolm Gladwell, economists call this the "80/20 Principle, which is the idea that in any situation roughly 80 percent of the 'work' will be done by 20 percent of the participants" (see Pareto Principle). These people are described in the following ways:
- Connectors are the people in a community who know large numbers of people and who are in the habit of making introductions. A connector is essentially the social equivalent of a computer network hub. They usually know people across an array of social, cultural, professional, and economic circles, and make a habit of introducing people who work or live in different circles. They are people who "link us up with the world...people with a special gift for bringing the world together". They are "a handful of people with a truly extraordinary knack [... for] making friends and acquaintances". Malcolm Gladwell characterizes these individuals as having social networks of over one hundred people. To illustrate, he cites the following examples: the midnight ride of Paul Revere, Milgram's experiments in the small world problem, the "Six Degrees of Kevin Bacon" trivia game, Dallas businessman Roger Horchow, and Chicagoan Lois Weisberg, a person who understands the concept of the weak tie. Gladwell attributes the social success of Connectors to the fact that "their ability to span many different worlds is a function of something intrinsic to their personality, some combination of curiosity, self-confidence, sociability, and energy".
- Mavens are "information specialists", or "people we rely upon to connect us with new information". They accumulate knowledge, especially about the marketplace, and know how to share it with others. Gladwell cites Mark Alpert as a prototypical Maven who is "almost pathologically helpful", further adding, "he can't help himself". In this vein, Alpert himself concedes, "A Maven is someone who wants to solve other people's problems, generally by solving his own". According to Gladwell, Mavens start "word-of-mouth epidemics" due to their knowledge, social skills, and ability to communicate. As Malcolm Gladwell states, "Mavens are really information brokers, sharing and trading what they know".
- Salesmen are "persuaders", charismatic people with powerful negotiation skills. They tend to have an indefinable trait that goes beyond what they say, which makes others want to agree with them. Malcolm Gladwell's examples include California businessman Tom Gau and news anchor Peter Jennings, and he cites several studies about the persuasive implications of non-verbal cues, including a headphone nod study (conducted by Gary Wells of the University of Alberta and Richard Petty of the University of Missouri) and William S. Condon's cultural microrhythms study.
The Stickiness Factor
The specific content of a message that renders its impact memorable. Popular children's television programs such as Sesame Street and Blue's Clues pioneered the properties of the stickiness factor, thus enhancing effective retention of educational content as well as entertainment value.
The Power of Context
Human behavior is sensitive to and strongly influenced by its environment. As Malcolm Gladwell says, "Epidemics are sensitive to the conditions and circumstances of the times and places in which they occur". For example, "zero tolerance" efforts to combat minor crimes such as fare-beating and vandalism on the New York subway led to a decline in more violent crimes city-wide. Gladwell describes the bystander effect, and explains how Dunbar's number plays into the tipping point, using Rebecca Wells' novel Divine Secrets of the Ya-Ya Sisterhood, evangelist John Wesley, and the high-tech firm W. L. Gore and Associates. Malcolm Gladwell also discusses what he dubs the rule of 150, which states that the maximum number of individuals in a society or group that someone can have real social relationships with is 150.