

Visibility of Targets. Werner Adrian. A classic and a reference on the subject.
Oh, BTW, you are using the concept of UX incorrectly. Not all system -> human interfaces are UX. I’m not completely ignorant on the subject. Several years teaching programming at the university level + many more developing for the private sector does give me a certain base to talk about the subject.
Same with Turd, he hates being compared to cheetos.