Is there a Visual Literacy Policy

By that I am referring to the level of detail (not to be confused with sharpness, pixel count, etc. etc.). To convey a measage, sometimes more detail is less effective. Studies have shown that people learn more from simpler images. For example, a sharp photpgraph of a person with a confused look on her face with a complex background, may not convey confusion as well as a more graphic rendering of a confused looking person with a simple background.

Also, am I correct that text bubbles should not be used, or are there exception?

Thanks to you who respond!