This one is extremely powerful and also a bit manipulative especially if the person is suggestive. So use it with your own responsibility and in an ethical way. Getting a positive response from someone is usually what we want. Whether it is making a sale, or promoting a viewpoint, we always want people to get on board. Nodding while you try to deliver your message is a powerful way to get the person to agree with you. People usually like mimicking, so they will most probably nod back while you talk. This will subsequently communicate to their brains that they have to agree with you.