The Holy Grail of selling would be to find the collection of psychological phenomenon that you can utilize to ensure you win the sale. The objective is have a sales routine that affects the buyer's decision-making facility in a completely predictable way.
This image of footprints in the sand is actually just one image. It has not been altered in any way, except that one of the four panels is rotated 180 degrees. You see either two or six indented footprints as well as the opposite (two or six) raised footprints. If you click on the image, it will periodically rotate 180 degrees.
Knowing that the image is just one image, and that it is really a photo of two footprints indented in the sand, try to see all eight footprints as indented in the sand. Difficult if not impossible! Your brain is creating an untrue image of the world. You cannot control that. Just imagine being able to do the same in sales -- predicting exactly how the buyer's brain will respond.
We are part way there, by applying the two techniques (the bonus question and the peak/end question) in The Peak Interview in a sales environment you take two small footsteps in the direction of The Holy Grail of selling.