Visual discriminability of headings in text

It is pointed out that writers and editors have powerful formatting and typographical tools available in word processing and desktop publishing software that can be applied to headings to visually reveal or signal the structure of text, and thus the author's perspective. Results of studies are presented which suggest that (1) visual discriminations among headings are easier for a reader to make when headings vary on fewer rather than more formatting and typographical dimensions, (2) size is the most powerful visual cue to a heading's hierarchical position, (3) relative size differences among different levels of headings of about 20% are more discriminable than are absolute size differences, and (4) formatting cues are perceived by readers consistently but not necessarily conventionally