As originally answered on Quora.com ...
This question might be better asked as can visualization help us to improve our public speaking skills?
Visualization is a technique often used by high-performance coaches for training athletes and other individuals who are actively trying to gain a competitive edge.
There is a technique behind visualizing. It is not likely to be successful if one focuses on negative aspects of their performance. Examples: focusing on their fear, focusing on the possibility of failure, not having a clear vision of the objective.
I was listening to a high-performance coach who was a guest on a podcast focusing on public speaking. He had worked with Michael Phelps in preparation for the Olympics. He related that whereas regular competitors at that level of competition would be in the water in the morning and the evening i.e. two practices every day. Phelps on the other hand, would only have one swimming practice in the morning. For the second session, instead of being in the pool swimming, he would focus on the videos of his practice. He would focus on every single stroke and visualize on how he could improve his performance, stroke by stroke. That’s quite a bit of devotion.
Now if we were to apply that level of scrutiny to our public speaking, how might we fare?
As mentioned earlier, its not likely to be helpful if we undertake it from a position of weakness. If you are fortunate to have a coach help you improve your speaking, they will likely focus on ways you can improve small elements of your speaking skills that will lead to long-term gain.
With or without a coach it is helpful to envision yourself being successful in your speaking presentation. I regularly walk through my presentation in my mind to ensure that I will have a good presentation. I commute an hour each way to and from work in my truck. That provides me lots of uninterrupted time to practice my speech in my head and envision my success.
I would suggest incorporating visualization into your speech practicing and see how it works for you. I have had success with it and highly recommend the practice.
Thanks for the question. Envision success!