By experimental research Robert Cialdini found out major principles of persuasion. He focussed on the behavior of  “compliance professionals”, e.g. people working in sales, adertising or marketing. People working in these fields find themselves often in a position where they have to persuade their vis-Ă -vis for a positive decision.
Usually a speaker isn’t in such a “dialogue” situation, but she / he also wants to convince the audience of an opinion or make them 
agree to the speech content. So why not try to adapt Cialdini’s principles of persuasion to your speech?
Reciprocation or “give & take”
It’s human nature that we respond to try to react in a corresponding matter to someone’s (friendly) gesture or action. This principle is used in sales – you get a taster or a freebie and feel obliged to buy a product or service. As a speaker you usually would not scatter little presents among your audience like pens or pocket lighters.
But sometimes you have prepared a handout of your presentation anyway. So why not handing it on to your audience with a remark like “It was an additional effort for me to prepare this handout / paper but I thought it might be useful for you.” May be you have arranged an object of demonstration or a special simulation to support your speech. Talk about it: “Especially to make it clear for you I have this and that, I hope you like it”. Receiving a “gift” like this makes your audience feel that they are in your debt. The need to “repay” can lead them audience to agree, for example if you need acceptance of a proposal or a project.
Commitment and consistency or “yes, yes, yes”
Once we are dedicated or used to an activity or an attitude we usually remain constant to it. Quite the same is with opinions or commitments. The challenge is to find a basic opinion or question the audience will easily approve. Have a look at your them main idea or assumption of your speech, is there a part in it acceptable for everyone? Then you can build on this first acceptance and create a chain of agreements that lead to your request.
Let’s make a simple example. If you want to convince your audience to exchange conventional bulbs to energy-efficient lamps
you probably won’t succeed with a statement like “You should exchange every bulb in your household immediately!”. Instead try this one
- For sure reduction of CO2 emission is a major challenge of our society.
- Do you agree that energy efficiency is a key factor for reduction of CO2 emission?
- And everyone can contribute to make energy consuptiom more efficient.
- Even small measures are helpful.
- It’s clear that it’s up to each and everyone of us to each do something about it.
- So a change to a change to energy-efficient lamps can be implemented easily by everyone.
Social proof or “success by imitation”
Our behaviour is mostly orientated to successful patterns we already know. Feeling uncertain about an issue we try to follow proven examples and decide in accordance.
Ask yourself: How do recommondations for a product or a service affect your personal buying decision? So by mentioning successful examples of similar cases in a speech your audience will follow the suggestions you make. Try to provide cases where the concept or the ideas of your presentation were already effective.
pictures:
S. Hofschlaeger / pixelio.de
Thommy Weiss / pixelio.de
Of course all of this is a rough description and simple categorization of personality types. Nevertheless it can be a guideline when you prepare your speech.