Most technical documents are formatted so that they are either left-justified (with the left margin aligned and the right margin ‘ragged’) or full-justified (when both margins are aligned). Although full-justified margins may appear to look more professional, they also require unequal spacing between the words so that the margins can match up. This sometimes gives the text a ‘Swiss cheese’ effect.
Regardless of how the text looks, which format is better for the reader?
Numerous studies have shown that readers read faster and comprehend better when the text is spaced consistently. Why? Because the reader’s eye can scan the lines more accurately when the spacing between words is consistent. This is especially true when the text includes numbers, symbols, formulas, and other non-word elements of text.
Ten to fifteen percent of the US population has dyslexia, which is somewhere around 40 million American adults. These people find it more difficult to read text that is full-justified.
In technical communication, one of our primary goals is to make the text readily understandable to the reader. That’s why the writers and editors at Shea always recommend to our clients that they use left justified margins.