Why we want things.

Any one of six universal principles of social influence can act as a catalyst to trigger an emotional response:

  • Reciprocation: We feel obliged to return favors.
  • Authority: We look to experts.
  • Commitment/Consistency: We want to act consistently with our commitments and values.
  • Scarcity: The less available a resource, the more we want it.
  • Liking: The more we like people, the more we want to say yes to them.
  • Social Proof: We look to others to guide our behavior.

In addition to the principles of social influence, there are psychological principles designers can leverage to increase engagement and help people to make informed choices. Making things easy, relevant, and trustworthy by building persuasive features into the interface helps elicit desired user behaviors—ones that align with the product’s business objectives.
Such psychological principles include:

  • Completeness: By nature, we feel the need to fill in gaps.
  • Positive Reinforcement: Letting customers know when they are doing well will keep them engaged.
  • Loss Aversion: People do not like to lose things once they have them, so alerting customers when they are about to lose out on something is an opportunity to maintain engagement.
  • Saving for Tomorrow: A U.S. study has shown that people are much more likely to make a commitment to spend money in the future than to spend it today.
  • The Power of Free: We are prone to go for free things, even if they come at a price later.
  • Susceptible Moments: Opportunities to cross- and up-sell must be timely so that they are delivered at the point at which people are most receptive.

Elisa del Gado: Persuasion in Design