NOW READ THIS!
What was the first thing that jumped out at you? It was that the sentence was entirely in uppercase. Did that catch your attention? It should have.
First, because it looks different from most of the text you read. Most of the reading you do is with a mixture of uppercase and lowercase letters, and predominantly lowercase letters.
Second, because all uppercase is now the convention of shouting in the world of Facebook, Twitter and e-mails. So in your mind, you added extra decibels to the sentence you were reading.
Controversy rages today as to when it is appropriate to use all uppercase in online venues such as Facebook and Twitter and offline venues such as billboards, signs and posters. The matter under debate is whether or not all upper case words slow down reading speed.
The basis for reading speed was influenced by the word shape model, a theory devised by James McKeen Cattell, a brilliant American scientist and psychologist in the late 1800s and the first half of the 1900s. He determined that people read by recognizing the shapes that letters make.
Lowercase letters, with their descenders (“p”, “q” and “y”) and ascenders (“b”, “d” and “h”) presented a more unique shape than all uppercase, which makes every word a uniform rectangle. Thus, the mind could pick out lowercase words more quickly than uppercase words.
This research has now been superseded by the parallel letter recognition theory. It is not the shape of the word but the pattern recognition of clusters of letters that help a person read. Studies now suggest that the human mind recognizes all of the letters of a word simultaneously and then translates that pattern into a word.
Reading is a process of stops and starts. The mind does not move smoothly over the words. Rather, each word is scanned and interpreted as the mind processes a word at a time, pausing between each word, then moving on.
Thus, in theory, the mind should not have any more difficulty reading all uppercase than reading mixed case or all lowercase.
Except that it does because the bulk of the text people read is in mixed case. So people are used to reading mixed case more than reading all uppercase.
The net effect is that reading mixed case is still faster than reading uppercase, not because of any inherent problems with uppercase but due to the relative lack of practice of recognizing uppercase letters.
Sentences and paragraphs are best written in mixed case.
There is a secondary reason for writing in mixed case: more space efficient. Type any sentence in all uppercase and compare its length to the same sentence in mixed case. The mixed case will always take up less print space.
This space consumption is important in today’s world of shrinking display sizes, as more content is consumed on mobile devices. Phones and tablets have much less space to display the text, so using all uppercase would require more scrolling and a less enjoyable user experience.
Fitting mixed case into sidebar text boxes can eliminate one more wraparound, which is crucial to readability.
So from a readability standpoint and a formatting perspective, mixed case with bold is a better way to emphasize the message than using all uppercase.
All uppercase is acceptable for logos and short titles when space permits, but for sentences, it is much better to use mixed case.