Are there any studies on the use of justified text in web apps? How does justification affect screen legibility?
Example of justified text:
No,for the simple reason that justified text can often create large blocks of white spaces which breaks the continuity of flow of words. To quote this article found in UX movement
As per this article about justified text in web accessibility,
However Justified text does have its place in print since the straight line of each margin can guide the eye across columns of text and the aligned columns help define the different areas of text creating a logical flow of words, thus enhancing readability
There are some important points that appear to have been completely overlooked.
It may be worth remembering that the use of justified text goes back a long way. Justified text is used in probably the most highly regarded and most valuable documents that exist.
It is only a failure of web typography that some web-browsers are unable to render justified text that does not contain defects like rivers. These were not a problem five-hundred or a thousand years ago.
Note the absence of gross defects such as rivers.
Now of course these are not easy to read, but the main reasons for this difficulty are not to do with the justification of the text, of more significance is the use of Latin and the use of a now unfamiliar black-letter typeface.
So whether to use justified text depends partly on whether you want to produce something beautiful or something mundane and ordinary.
You shouldn't be asking this question at all. You don't have to choose.
You can offer the reader a choice or a range of choices. This is all about CSS style sheets, not about HTML content.
The whole point of CSS is to solve this problem for you.
It is a comparatively simple matter to offer the reader a choice of visual styles that are remembered using a cookie. One of the stylesheets on offer can be optimised for dyslexics, another for those with impaired vision, another for those with red-green colour-blindness and so on if you wish (or feel is needed).
You absolutely do not need to impair or degrade your website so that it cannot be enjoyed by those who appreciate good typography.
I'm, at best, a mediocre web designer. However I thought I'd better test my assertion that justified text need not create the ugly rivers that cause problems with readability.
I created a small basic test page. It seems to work about as well as I would expect in the current browsers I have available.