47 subjects were given around 20 small, manual tasks to complete, one at a time. Experimenters randomly interrupted completion of half of these tasks. After, subjects were asked to recall as many tasks as possible.

There was a 90% higher recall of incomplete and interrupted tasks than those completed.

Make important task completion frictionless. If customers leave your site without finishing their order, make it effortlessly easy to get that completion feeling, such as allowing for completion with a single click, tap or swipe. 

Focus on completion’s emotional release. Providing reward incentives for task completion actually demotivates consumers. Instead, remind them not just of the product they’ve not yet bought, but of the feelings that this ‘purchase task’ will unlock. 

Make known campaigns incomplete and interactive. Greater familiarity with an advert increases consumer ability to complete an interrupted ad message. Active participation also boosts ad memory (Heller, 1956). So if your popular campaign’s reaching its end, consider a special second follow-up version that allows for active participation in completing the ad message. 

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.