Influence by Robert B. Ciadini is about how to get people to say YES and behind the HOW of getting the results you desire. Understanding the psychology behind tactics like free samples, social acceptance, positioning yourself as an expert and the scarcity tactic will help put you in a position to influence.

The Psychology of Persuasion can be broken down into 6 basic categories:

1. Consistency – We have a deep desire to remain consistent with what we have already done. We behave consistent with our commitment or earlier decision and convince ourselves that we have made the right choice. Consistency is valued and adaptive. We associate a high degree of consistency with personal and intellectual strength. Consistency is also associated with logic, rationality, stability and honesty.

2. Reciprocation – We have the need to repay when one person provides something to us. There is a general distaste for those who take, so we go to great lengths to repay. Free samples and gifts engage the reciprocity rule.

3. Social Proof – When others are doing it, the actions are more appropriate. We use social proof for convenient shortcuts on how to behave.

4. Authority – Obedience to authority is mostly rewarding, we recognized authority should be followed. We see authority with superior knowledge and judgments.

5. Liking – We are more likely to say yes to the request of someone we know and like. The idea that someone likes us, can be an effective device for return liking and willing compliance. We are suckers for flattery and believe praise!

6. Scarcity – The idea of potential loss plays a large role in human decision making. People are more motivated by the thought of losing something, than gaining something of equal value. Scarcity is a source of power, we use an items availability to help us quickly decide its quality. We assign positive qualities to the item to justify the desire.

You can use these categories of the psychology of persuasion to both influence people and avoid unwanted influence. We normally do not fully analyze a situation before making a decision, but focus on a single feature. Stop and consider how external and irrelevant evidence is effecting your decision.