There is a better explanation for the readability of ragged margin than given above (unless I missed it): uniformity is the enemy of readibility. Raggedness helps the eye maintain its place (i.e., current line) in the document, justification provides no help at all.

I am sure of this because narrower columns improve the legibility of justified text. And it easier to stay on line with narrower columns (the main reason they are used in the first place). However, narrower columns actually produce higher variability in horizontal spacing with justified text (if you do the math, you can see why this is so), so if horizontal spacing is causing the readibility problem, then narrow columns should be even worse with justification.

Greater uniformity is the reason why all caps and san serif fonts are harder to read in body text compared to lower case and/or serifed fonts.

Further, I am surprised that it is taken above as univeral fact above that justification produces greater text density. That is only true when hyphenation is used with justification and not used with ragged. I.e., it’s not due directly to the justification, it’s due to the hyphenation.

Word processing software does have limitations, but sometimes it is just a matter of knowing the software. For example, most documents can be beautifully prepared with full justification in WordPerfect. In Microsoft Word, the text often looks too spaced out in full justification. To fix this in Word 2007 go to the Office Button and click on Word Options at the botton. Then click Advanced. Scroll down to the bottom and click Layout Options. This will open a large menu of options. Check the box “Do full justification the way WordPerfect 6.x for Windows does.” You will need to apply this to every document that you fully justify. Or you can create a master document or template that you use with this box checked and then just “Save As” for each new document.

Full justification saves space and paper. It is eco-friendly!

Proportional fonts were developed to remedy this problem. In proportional fonts such as Times New Roman, characters are not the same width but are each assigned their own point value. The idea was that the word processing program would be able to fit more characters onto a line (for example, 50 Times New Roman characters vs. 40 Courier characters), thus eliminating the large gaps between words. Spaces in proportional font do not have a fixed value. Instead, the program is able to increase or decrease their point value depending on how many characters it is trying to fit into a line (which explains why it is almost impossible to get tabbed columns to line up using proportional fonts.)

Unfortunately proportional fonts were not a perfect solution. The shorter the line, the less room the program has to work with, which is why you often see large spaces between words in the final line of a right-justified paragraph. Even throughout the rest of the paragraph, the spaces between words are not consistent, as the program is constantly adjusting the spaces between words in order to maintain that justified right margin. This, I think, is what makes it difficult to read text that is right-justified. The eye is constantly having to adjust from line to line as the spacing is different on every line. Even if we do not consciously notice the constantly changing spacing, it still takes more effort to read (much as a serifed font is harder to read than a sans-serif font).

Ragged-right text is easier to read because each line is a different length from its close companions therefore the eye finds it easier to “fly-back” to the beginning of the next line.

If you want to slow your reader down (newspapers collect data on length of time spent reading) and make a page look nicer as a design entity then carry on using justified text. By the way, anyone who uses Word as a page design tool is misguided. Word is a word processor. Use a professional layout system such as Adobe Indesign (the best) or Quark XPress.

You refer to using justified text “correctly.” I agree with you if by that use mean using typesetting software. But there’s nothing the user can do to fix the spacing shortcomings of word-processing software.

Ken