The middle of a presentation is made up of various types of contrast. People are naturally drawn to contrast, because life is surrounded with it. Day and night. Male and female. Up and down. Good and evil. Love and hate.
Your job as a communicator is to create and resolve the tension created by contrast.
Building highly contrasting elements into a presentation holds the audience’s attention. Audiences enjoy experiencing a dilemma and its resolution—even if that dilemma is caused by a viewpoint that’s opposed to their own. It keeps them interested.
The presentation audience wants to know if your views are similar to or different from their views.
While listening to a presenter, audience members catalog and classify what they hear. Having come into the room with their own knowledge, and biases, they are constantly evaluating whether what you say fits within their life experiences, or falls outside of what they know.
It’s important to know your audience so that you can understand how your views are both similar to and different from theirs. There will usually be some disparities. A rather obvious business example would be that you want them to buy your product, and they don’t want to spend the money.