How we change what others think, feel, believe and do
If I am interested then I will pay attention.
Interest leads to attention
The AIDA sales model says that the first step of selling is to get attention, which makes a kind of obvious sense. After all, without the attention of the other person, you cannot have any kind of conversation. The same is true of any kind of persuasion. If you want to maintain attention, you will need to constantly play to their interests throughout any interaction.
You can grab attention in crude ways, but shock tactics tend to have only a short-term effect. To sustain the conversation, working with interests is by far the most effective method.
Chances are, you experienced bodily sensations of some kind. There may have been a powerful tingling shooting up your spine. Your might have had a hot flush rushing up you neck and around your face. You toes or fingers may have twitched at the prospect to come.
Thus when other people are feeling something, there are likely to be visible signs, such as skin color changes and different facial expressions. Watch out for these signals, especially after you have done or said something that is intended to stimulate their interest. You can also discover their interests by observing them in everyday action.
Interest is selfish
In what are people interested? Are they interested in your problems or products? Are they interested in hearing you talk? No, not really.
What about their interests in being nice to other people and saving the environment? These, too, can be traced back to things like being nice to others so they will be nice back, and saving the environment so you and your descendents will survive.
Biologist Richard Dawkins, in 'The Selfish Gene', explained how, at the most fundamental levels, we are simply machines for propagating our genes, and all our actions can be explained in this light.
Interests are in achieving goals
If I have decided that I want to buy a new car, then a car salesman has my attention. If I have just bought one, then they have no chance of selling me another and I am not interested.
If you want to persuade someone to do something, then it helps a great deal if you can find out what they need, want or like.
Interests are in avoiding suffering
We can have positive goals and we can also have negative goals, where we seek to avoid bad things. The degree to which people will choose one over another is affected by the attraction vs. avoidance preference that people have.
Bad stuff is usually more important and thus of greater immediate interest than good stuff. If you were in a bank and a robber came in, then most people would lie on the floor rather than tackle the man with the gun--discretion usually being the better part of valor.
Interests are in stimulating pleasure
What we often consider as interest is stimulation of the pleasure zones in the brain. If I am interested in going to the movies, it is because all movies, as all entertainments, are designed just to cause that pleasure.
This is a broad and general class of positive goals, where we are not particularly furthering our selves in life, rather the goals are about relaxation and the general seeking of immediate pleasures.
Many people drift through life with few driving goals. They accept the pleasures that fall in their path and try to avoid less pleasant things (which often include the uncomfortable truth).
Interests are not positions
To work with and address the other person's interests, you have to first find them.
In negotiation, people often take fixed positions and defend them like castles, building logical and emotional fortifications behind which they hide and shoot down on all apparent assailants.
When two people or parties do this, you have a long battle of attrition, with the victor having a hollow victory, with the vanquished other person complying only because they have been beaten, and not because they are really enthused.
Taking a 'position' is clearly not the solution. The real solution is to find out the interests behind the position and then find other ways of addressing those interests.
Seek the goals
When people take positions or their interest are unclear, ask what they are trying to achieve with those positions. Assume that they have goals which are valid and real, at least for them (and if they have not thought about it, for their subconscious).
Beware of coldly asking 'why'--you don't want to sound like the Spanish Inquisition. Gentle probing is usually a much more effective method.
Find out their interests by asking questions and watching for the visible signals. Look for the WIIFM factor (What's In It For Me?). Also find their priorities amongst interests and their preferences for avoiding pain vs. seeking pleasure.
You now have a list of their hot and cold buttons, which you can press deliberately for desired effects. Pressing buttons accidentally is a great way of turning a potential convert into a certain antagonist.