Diffusion and Contagion in Networks
This study, conducted by Matthew O. Jackson and Dunia Lopez-Pintado, investigates the way in which a disease or behavior diffuses a network that exhibits homophily –– the tendency for individuals to develop stronger bonds with those who share defining characteristics with themselves. For example, homophily can be exhibited across characteristics such as education level, age, or ethnicity, and these groups may have varying levels of susceptibility to disease infection. One interesting aspect of this study is Jackson and Lopez-Pintado’s examination of the results of diffusion from a small introduction in a homophilous society. The researchers found that societies exhibiting more homophily foster more initial diffusion within the group and can consequently diffuse the information or disease to the wider society. This stands in contrast to less homophilous societies, which seem to foster less initial diffusion and thus have more trouble diffusing the disease or behavior to the wider population from these smaller starting seeds.
This paper relates to our discussion of diffusion in class. As opposed to assuming that individuals imitate the entire world, we were introduced to the idea of imitating the decisions of our own neighbors in our social network. In other words, we shifted our focus to studying the spread of things locally. Although individuals do not have a choice of whether or not they will be infected with a disease, it is interesting to look at the ways in which the number and or existence of densely knit clusters affect the spread of a disease or of information more generally. The results of this study can also be related to the adaption of new technology; if it is introduced in a small seed of a homophilous society, according to Jackson and Lopez-Pintado, it will diffuse within this group and in turn have more of a chance to be introduced to other groups through weaker ties. In contrast, if a new technology is introduced to a less homophilous society, it is less likely to have that initial traction and diffuse widely through society.