As an advanced visualization teacher I appreciate clear ways to understand ‘why’ it works that you can imagine what you want and soon you will have that. This is a great article for understanding that.
One reason it works to ‘index’ information you are learning for easier recall:
“Fostering visualization of any content (curricular or otherwise) by targeting and using the occipital lobe as the central point of processing the information is one of the strongest ways to help that material enter the brain… and stay there even as external stimuli compete for attention.”
Occipital lobe- located at the back of the head, this section occupies some 20% of the brain’s overall capacity and is responsible for vision and being able to visualize scenes never actually witnessed before.