The typographical factors of text chunking, line length, and line-length variability interact to influence reading comprehension:

• Text Chunking: Chunking (breaking lines at phrase boundaries) provides a reading advantage when line length and variability are constant, but this benefit can be outweighed by the disadvantage of the resulting irregular margins (high line-length variability).
• Line Length: Medium-length lines offer a reading advantage when chunking and line-length variability are constant.
• Line-Length Variability: Low variability (i.e., a regular right margin) is generally advantageous for reading.