Word: Social Proof

Definition:  People are influenced and guided by the behaviors, actions, and beliefs of others.

Thoughts: Social proof can be used in design to influence users' thoughts and actions. Take a moment and think about Amazon's review section. Would you really buy a microwave that was reviewed by 300 people and had 1 out of 5 stars. Most likely, not. Why is that? Because the crowd has a strong influence on your decision in this situation, that's why.

Dr. Robert Cialdini’s book Influence: The Psychology of Persuasion details how social proof plays into human insecurities and the innate desire to do the right thing.

Social proof can be utilized in user experience design in a multitude of ways like demonstrating product credibility (through reviews and ratings) and encouraging adaption and acceptance (like following a Twitter account because you see many others follow the account as well).

Question: How, if at all, has social proof influenced the development of social media services? Is social media even comparable to the definition of social proof outlined above?