Social Influence

Diffusion and Contagion

• What we do is influenced by what others do
• Network effects
  • Standards, languages, technologies
• Social constructs
  • Concepts or things have meaning and importance through social
• Beliefs

Simple contagion

• Small world networks make simple contagion (like COVID-19) is really hard to stop!
• Most interventions are network interventions
  • Stopping travel attempts to block “long” ties
  • Social distancing and shelter-in-place attempt to reduce degree
• The most important people to influence are those with high betweenness centrality

Example

Complex contagion

• Most communication-related diffusions are complex
  • You don’t change beliefs/behavior just from influence from one other person
• Complex contagions require multiple ties between groups
  • This is one reason groups can persist in different beliefs

Example

Special People

• Why is the Mona Lisa the most famous painting in the world?
  • Because there had to be a most famous painting – success begets success (rich-get-richer)

How does this apply to networks?

• Can we predict who will trigger large-scale information cascades?
  • Not very well
  • If we look in hindsight, a viral tweet seems genius, appropriate, and well-timed
  • There were likely hundreds or thousands of similar tweets
• Luck + (ever-changing) structure of networks matter more than attributes of information or information spreaders
• Network position is also closely related to luck!