A common belief, especially among typographers and designers, is that text in all caps is difficult to read.
The common wisdom argues that this is because capital letters offer fewer visual clues as to their identification. It’s said that lowercase letters are more easily distinguished because of their ascenders and descenders. This seems to make sense if we consider the shapes of each letter:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
a b c d e f g h i j k l m n o p q r s t u v w x y z
It’s clear that, in the case of the capital letters, each has exactly the same high (except the tail of the Q), while the lowercase letters vary. According to some, we rely on this variation to identify letters quickly.
Besides individual letter recognition, some argue that we recognize whole words at a time. That is, for some words we don’t analyze the individual letters that make it up, but rather we focus on the form of the word in its entirety. The longer it takes us to recognize a word, the slower we read. To illustrate this, let’s consider these two words:
It’s possible that DANGER and DANCER aren’t as easily distinguishable as danger and dancer, no doubt because of the descender on the lowercase g. But is it really likely that we store images of every word in our mind? Perhaps for very common function words such as copulatives and articles… But words like dancer?
Even with all this in mind, we can’t conclude so easily that text written in all caps is inherently difficult to read. In a study by Fryser and Stirling (1984), librarians were tested on their speed in looking up records written in various formats. The results demonstrated that there was no difference in performance between the records written entirely in caps and those written with initial caps. Greer, et al., in 2005 reached similar conclusions in a study of emails in a business setting, except with the caveat that users were less likely to want to read texts written in all caps.
It seems that we may truly have an easier time reading lowercase texts, but not because of any inherent difficulty with reading texts in all caps. Instead, it’s simply a question of frequency. We see lowercase letters more often, so we read them most easily.