How Friends and Strangers Shape What We Do

People often copy what others do, especially friends. But does having many friends help or slow down the spread of new ideas or behaviors?

The Debate

• Close-Knit Communities: Some believe behaviors spread faster and wider in groups where everyone knows each other well.
• Random Connections: Others argue that behaviors spread better in groups where people are connected randomly, without many close-knit circles.

The Experiment

Researchers created a model to test this:

• Adjusted the likelihood of people copying others.
• Compared behavior spread in two group types:
• Tightly Connected Groups (like a close-knit community).
• Randomly Connected Groups (like strangers meeting at a party).

Surprising Results

• Behaviors spread just as far—or even farther—in random groups, even when friends influenced each other.
• Close-knit groups helped in some cases, but this was not the usual pattern.
• Close-knit groups were less effective when:
• People stayed influential for longer.
• People had more friends.
• More friends were needed to start copying a behavior.
• Close-knit groups only outperformed random groups 22% of the time under the best conditions.

The Trade-Off

• Random Connections: Help behaviors reach more people.
• Close-Knit Connections: Make it more likely that friends will copy each other.

Conclusion

If you want a behavior to spread widely, having some random connections might be more important than having a tight-knit group of friends.