32 dog-phobic children were split into 3 groups and shown 8 videos of either one child playing with a dog,  many children with different dogs or no dogs, and then asked to interact with a dog themselves.

Those who watched another child play with a dog performed far better. Those who watched many children also kept this up a month later.

Provide mental shortcuts through the judgements of others; the more people, the more persuasive.  First-time consumers of your product will benefit the most from this approach. 

Persuade with similarity. We're most influenced by those who we deem similar to ourselves. Communicate characteristics relevant to that segment, such as proximity, gender / age, profession or social class to successfully direct behavior. 

Use role-models. Understand the emotional drivers of your audience and seek out positive, aspirational individuals to direct specific consumer decisions and reinforce behaviors.