WHAT YOU ARE ABOUT TO READ IN THE NEXT PARAGRAPH IS COMMONLY BELIEVED, BUT NOT TRUE — You read by recognizing the shapes of words and groups of words. Words that are in all capital letters all have the same shape: a rectangle of a certain size. This makes words displayed in all uppercase harder to read than upper and lower case (known as “mixed case”). Mixed case words are easier to read because they make unique shapes, as demonstrated by the picture below.
OK, NOW THE TRUE STUFF STARTS — When I started this article the topic was supposed to be why all capital letters are harder to read. Like most people with a usability background or a cognitive psychology background, I can describe the research — just what I wrote in the first paragraph above. I decided to look up and cite the actual research rather than just passing on the general knowledge and belief.
The research doesn’t exist, or “It’s complicated” — Something happened when I went to find the research on the shape of words and how that is related to all capital letters being harder to read. There isn’t research showing that exactly. It’s more complicated, and ultimately, more controversial. In July of 2004 Kevin Larson wrote an article that is posted at the Microsoft website that explains in depth all the research on this topic. I’ve picked out several ideas from that article and am presenting them here. A link to Kevin’s article, plus some of his research citations are at the end of this blog for those of you who want more detail.