The Harvard Business Review ran an article this month** about a study that shows that in educational environments, textbooks where the text is written in an uncommon font, especially a hard-to-read font, are providing better retention of the material than textbooks written in traditional fonts. The theory is that these fonts make the reader work harder, and in so doing, the reader remembers the material more. Perhaps the effort that we take in comprehending something is positively correlated with ability to remember that information. This makes sense.
Now let’s just take this to what you might be guessing is my logical, although potentially quite fallable, follow-on idea: maybe maps that are hard to read, that are so awful that they make the map reader really study them just to get some basic understanding out of them, increase the map reader’s ability to remember their content?
Now, the fear with this idea, and with the textbook study as well, is that if something is hard to read, a casual audience may just skip it completely rather than try to decipher it. This would be especially true when the material is not something that the reader, or map reader, is expecting to be tested on.
However, we might want to experiment with some variables in map design to see if it holds true. Cartography thesis anyone? The obvious variables to test would be maps with garish colors, or hard to distinguish colors; hard to read fonts on the labels; or confusing line work that overlaps and intersects. Hey, maybe there’s a use for this map afterall!
*I’m not seriously suggesting you make bad maps, people! It’s just an idea for further exploration. 
**Hard-To-Read Fonts Promote Better Recall, Harvard Business Review
#1 by Kristen Grady on March 13, 2012 - 6:12 pm
Interesting!
Here’s an alternate idea: Maybe instead of making a bad map, make a totally outrageous, blingy map that actually manages to embody good map design, but that doesn’t LOOK at first terribly informative. Suck the viewers in with something wild and then make them work, like in a treasure hunt, to find all of the map goodies hidden from immediate view. Make a map that visually holds (stimulates) the viewer but that upon examination slowly reveals “oh wow!” after “oh wow!” Make maps that enable discovery.
I imagine the longer you stare at a map, the more of an imprint it’ll make on your memory. It’s the same principle that you’re talking about, but without having to sacrifice good map design.
#2 by Gretchen on March 13, 2012 - 7:33 pm
Great idea!
#3 by @geoviews on March 14, 2012 - 4:59 am
Increase Memory Retention via Bad Maps? http://t.co/725Zb6uy
#4 by JRigs on March 14, 2012 - 1:15 pm
In a sea of white sheep, the name of the black one is the only one most will remember.
I think it has less to do with difficulty, bad design, or working harder to read than it does with standing out from the crowd.
#5 by Gretchen on March 15, 2012 - 9:30 am
@JRigs – In the article they mentioned that if a hard-to-read font became ubiquitous, then this would negate the memory retention efficacy, because at that point people would have trained themselves to read it more easily. I think this speaks to your comment about standing out from the crowd.