I was sent a pre-print of the following paper by Gordon Legge and Charles Bigelow after asking Legge about some critical comments he made on Miles Tinker’s work: “Does print size matter for reading? A review of findings from vision science”
Now it’s available from the Journal of Vision here:
The comments below are mostly cobbled together from Legge and Bigelow’s own words.
Legge and Bigelow present evidence supporting the hypothesis that the distribution of print sizes in historical and contemporary publications falls within a psychophysically defined range of fluent print size — the range over which text can be read at maximum speed. While economic, social, technological, and artistic factors influence type design and selection, they conclude that properties of human visual processing play a dominant role in constraining the distribution of print sizes in common use.
They begin by discussing metrics for print size used by typographers and vision scientists. “Confusion over definitions of print size has been an impediment to communication between the two disciplines, but common ground is necessary to understand our hypothesis.” This is probably the most thorough and helpful discussion on type measurement I’ve read.
Legge and Bigelow go on to discuss theoretical concepts from vision science concerning visual size coding that help inform an understanding of historical and modern typographical practices. Topics in this section are: Oculomotor limitations; Spatial frequency representation of letters; and Visual span and crowding. Included in this section are observations on optical scaling.
In their historical survey, Legge and Bigelow found three main trends: “(1) extension of type size range from a narrow cluster of fluent sizes in the 15th century to a broader range including several subfluent sizes in the 16th and 18th centuries; (2) nearly stable size range from the 16th to 18th century; (3) proliferation of type sizes in the subfluent range, from zero (for roman types) in the 15th century to 37% of the sample of typefounders’ specimens in the 18th century.”
I think the paper is ‘must reading’ for anyone interested in where typography and the science of reading meet.