When you get others to vote your way, quit smoking, buy your product or go on a date, you persuade them. As Richard Perloff notes in the book "The Dynamics of Persuasion," the study of persuasion is about changing people's attitudes and the methods for changing them. Social psychologists and communication experts have identified several techniques that are effective when you want to be persuasive.
Appeals to Logic
Chose a rational approach to persuasion when your logic is compelling. Present indisputable facts simply, and invite the listener to "see for himself." This technique works best when logical and rational arguments make your perspective preferable.
Appeals to Emotion
Persuasion that appeals to feelings, especially fear, can be effective. When the listener does not pay close attention, is hurried or does not feel that she has a personal stake, then appeals to feelings, especially fear, can be motivating. Political ads have increasingly taken this approach in recent years.
The Foot-in-the-Door technique gains compliance with a request. Start by asking for something small; once that request is granted, ask for the bigger act of compliance. It is easier to get a person to agree to your main request if he has already acquiesced once. The name "Foot-in-the-Door" is a historical reference to the door-to-door salesperson, who long ago knew how to make a sale to a reluctant occupant. He would ask for a glass of water or other small favor from the resident; after he was invited inside, he made the real request.
If you make an unreasonable appeal that is bound to be turned down, then a smaller request is more likely to be granted. This technique is often used for fund-raising or in recruitment of volunteers. If the potential contributor can't afford to donate $5000 -- and you knew that all along -- then you ask if he would be able to help with $15.
Leon Festinger's Cognitive Dissonance Theory asserts that people are motivated to change their attitudes to feel consistent. If they do not like or approve of something, but then are induced to do something small that conflicts with their original attitude, then they may change their overall appraisal of the situation. The change of attitude follows because they do not want to seem inconsistent.
Evoking Social Needs
People have a need to be social, fit in and be like their friends and neighbors. For this technique, emphasize that "most people" have the belief you are promoting. The herd will follow. You see this method -- the bandwagon -- often employed with social media, when you are shown products your friends "like" or the brand they endorse as "fans."
Other contextual factors impact the likely effectiveness of persuasion techniques. The most effective communicators have expertise or are considered trustworthy. Also, when communicating, the first of a series of communications has the most impact, and the last thing that you communicate is the best remembered argument.