This is a VERY low-fi description of the psychological theories at work - as it pertains to behavior adoption and network theory - but certainly is easy to digest. Influence is largely based on the shape of the network that connects individuals and and the position said individuals have in the network. Their proximity to the core of the network makes all the difference between how fast a rumor spreads or if the information will reach them at all. Not only that but how likely we are to adopt norms and stick to them Very powerful.
As such, our connection to each other has more impact on the decisions we make than what we perceive to be our own free will. Our likelihood to take on behaviors depends on two key factors - Attitudes and Adoption - both of which require very dense undertakings. However, when done well…can make the difference between wearing over-the-ear headphones vs ear buds or maybe even stopping the spread of a STD.