To deliver effective data visualizations, we need to understand our audience: human beings.
There are some rules that we need to know when dealing with humans. These are based on sound psychological studies, and therefore, aren't always true! They are good guidelines that apply to the majority of the population, but we really need to know that you can't please all of the people all of the time.
One of the things that humans really excel at is recognizing things that they have seen before or look similar to things that they have seen before and associating those things with other similar things that they have experienced before. As we tend to share a lot of cultural experiences, many of us will share the same generalizations. For example, you might have seen this in your Facebook or e-mail in the recent past:
"Olny srmat poelpe can raed tihs.
I cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid...