A screenplay is a de facto movie and anything presented will eventually have to be literally photographed (or said.)
Understanding why this works lends insight into human beings, your target audience. I learned this when I was taking an acting class. The teacher was stressing a point on how we should invest words with meaning. For some reason, he used this example:
“When I say dog, you’re picturing a dog. It may be a chihuahua or dalmation, but it’s a dog.” I’ve heard a version of this from a variety of acting teachers and improv teachers. It’s held to be true, and in most cases it is.
But I wasn’t picturing a dog. I was thinking of the word. Yes, canis canis, man’s best friend was hovering in my thoughts, but so was the verb, it dogs my thoughts, or the 50s slang, my dogs are barking.
When I asked him about this, he didn’t seem to be receptive to it’s possible truth or the implications. Some people are incurious.
A few years later, I read a memory book, which talked about visual pictures. They used an example like this to show how images can be subverted in interesting ways:
“A fellow hears a noise so he goes to his closet and grabs a bat. The bat flaps it’s wings and flies away.”
The implication was that most people will picture a wooden bat, then see it sprout wings in a confusing, absurd way, and then realize that it’s an animal bat and see that image instead. I didn’t. I was thinking about the word. “Oh yeah, they sound a like. I see what you did there.” I was getting a similar experience from language, but not the one the author expected me to have.
So I did more research and found that while most people experience language in an entirely visual way, some do not. There exist a rare subset of people who can’t form mental pictures at all. I’m not quite that bad, but I’d rate my ability to form mental pictures as lower than the average bear. Subpar. Learning how my essential truth was different than the general audiences helped me tailor my language in a way that communicated more effectively.
It may be that you can’t form visual images. Neat. You compensate for this by being better at abstract thought and narrative logic. It may be that you have perfect visual recall. Neat. Most people don’t. Understanding and having a good estimate as to what the average audience member needs to envision will help you clean up your scene description and to focus on the details that are interesting and essential. essential details.
Understanding where you fall on the spectrum helps you understand yourself, the audience, writing, communication and everything.