Here's a study with practical implications - at Ohio State, researchers found that students were better able to learn a new mathematical system when symbols were plain and not visually distracting.
Said Dr. Vladmir Sloutsky, "Many teachers believe that concrete materials make learning more fun for students, and that will increase their motivation and help them understand the concepts,” he said. “While this may be true, in many cases, the concrete materials also interfere with what they are trying to learn.” A reduced version of the stimuli are shown below. The actual figures were apparently in color - to accentuate possible distracting factors.
The press release of the article is titled "Students Learn Better When the Numbers Don't Talk and Dance". The truth is really not really so simple, but still this study is a good reminder to avoid unnecessary distractions in the visual presentation of lessons. In some cases, movement or color can enhance the memory of the items presented, but its true, excessive detail to surface or other insignificant aspects of objects can lead to more confusion.
In the Sloutsky's study, the task demands were fairly high (artificial mathematical task for college students)so that simple symbols simplified the perception of categories and relationships, reducing distraction and demands on attention and memory.
This may be why many designers and inventors prefer to sketch generally when brainstorming or working with new ideas.
Simple Visuals Study
Students Learn Better When The Numbers Don't Talk And Dance