User:Nuujinn/rivers/

Related studies
There are other studies that could be relevant to sentence spacing, such as the familiarity of typographic conventions on readability. Some studies indicate that "tradition" can increase the readability of text, and that reading is disrupted when conventional printing arrangements are disrupted or violated. The modern standard for the Web and published books, magazines, and newspapers is single sentence spacing.

A widespread observation is that increased sentence spacing creates "rivers" or "holes" within text, making it visually unattractive, distracting, and difficult to locate the end of sentences. Comprehensive works on typography describe the negative effect on readability caused by inconsistent spacing, supported in a 1981 study which found that "comprehension was significantly less accurate with the river condition." Another 1981 study on cathode ray tube (CRT) displays concluded that "more densely packed text is read more efficiently ... than is more loosely packed text." This conclusion is supported in other works as well.

Canadian typographer Geoffrey Dowding provided an explanation for this phenomenon:

"A carefully composed text page appears as an orderly series of strips of black separated by horizontal channels of white space. Conversely, in a slovenly setting the tendency is for the page to appear as a grey and muddled pattern of isolated spats, this effect being caused by the over-widely separated words. The normal, easy, left-to-right movement of the eye is slowed down simply because of this separation; further, the short letters and serifs are unable to discharge an important function—that of keeping the eye on 'the line'. The eye also tends to be confused by a feeling of vertical emphasis, that is, an up & down movement, induced by the relative isolation of the words & consequent insistence of the ascending and descending letters. This movement is further emphasized by those 'rivers' of white which are the inseparable & ugly accompaniment of all carelessly set text matter."

Some studies suggest that readability might be improved by segmenting sentences into shorter word phrases. Mid-20th-century research on this topic resulted in inconclusive findings. A 1980 study split sentences into phrases of between one to five words with additional spacing between segments. The study concluded that there was no significant difference in efficacy but that a wider study was needed. Numerous other similar studies in 1951–1991 resulted in disparate and inconclusive findings.

Finally, various studies have been conducted on the readability of proportional vs. monospaced fonts. These studies typically did not decrease sentence spacing when using proportional fonts or did not specify whether sentence spacing was changed.