1. “Connected” At Last Networked Life CIS 112 Spring 2010 Prof. Michael Kearns

2. What’s Different? Backgrounds of Christakis and Fowler –practicing medical and social health researchers –more likely to conduct survey studies, examine social interactions in detail Compared to “The Tipping Point” –considerably less anecdotal –almost all claims backed up by scientific studies Compared to “Six Degrees” –almost entirely empirical –field studies of social networks and contagion vs. math models and data analysis Detailed tracking of influence and contagion –in the physical world, not online/virtual –details of individuals in the social network –tracked over many years/decades –much of it based on the Framingham Heart Study data –contagion: from metaphor to mechanism

3. Christakis and Fowler “Rules” We shape our network –deliberate structuring/restructuring of our social NWs –contrast with “passive” network formation models considered so far –later: “economic” network formation models --- closer to C+F, but… Network shapes us –declining IQ of later-born children and network structure –divorce as a devastating reduction of clustering coefficient (0.52 in USA) Emergent behavior in networks –“Social networks can have properties and functions that are neither controlled nor even perceived by the people within them.” –flocking/schooling, stadium waves, standing ovations,… –much more coming in “Micromotives and Macrobehavior” Three degrees of influence –a claim about dynamics of influence, vs. static structure (6 degs of separation) –applies to word-of-mouth recommendations, weight gain, ideas, happiness…

4. Emotional Contagion Highly localized: “laughter epidemic” in Tanzania 1962 Evolutionary benefits of emotion contagion –herding behavior, protection from predators; contagion of courage –maternal protection –may predate, and be faster than, oral communication Case studies of Mass Psychogenic Illness (MPI) –perhaps easiest to identify and study –Tennessee 1998: phantom fume epidemic; contagion of anxiety –NYC 1990: Triborough Bridge “sweetness” epidemic –Now: “nut free” schools? What about more diffuse contagion?

5. Moods, Health and Habits Let’s look at the Christakis-Fowler papers on: –contagion of happinesshappiness –contagion of lonelinessloneliness –contagion of obesityobesity –contagion of smoking (cessation)smoking