In Counterpunch, Fred Smeijers talks about the importance of word shapes in how we read:
At the root of configuration or overall visual arrangement is the design of the word. . . . Though it might seem that the type designer’s aim is to make new characters, the real goal is to create a new word-image. [ch. 4, p. 29]
Good type leads to good word shapes which leads to good comprehension. Makes sense, right? It’s a concept I’ve read about elsewhere, but as I try to develop a brief for this whole math type issue, it leads to some additional questions. Namely, how do we read word shapes in math? As I’ve mentioned before, equations don’t really work as words quite the same way, and comprehension is a little harder since you can’t easily rely on context to clarify individual characters. Equations have basic rules for structure and notation, though, so there are conventions that aid comprehension in that context. So what kinds of patterns emerge form those rules? What are the functional “word shapes” that make math notation comprehensible? And — most importantly — how can type be optimized to make those mathematical word shapes easy to read?
Spacing in math is, in general, much looser than in text since it’s often a collection of symbols and operators. In a way, each symbol is a noun and each operator is a verb. Rows of symbols are usually shorthand for values multiplied by one another, and looser spacing helps clarify their separation from one another. You may find actual words like “sin” (sine) or “cos” (cosine) scattered within, set in roman rather than italic. These words ought to be spaced normally. You also have changes in vertical positioning all the time — superiors, inferiors, division, limits, matrices, etc. Readability, then, has to factor in the different meanings of space, different meanings of style, and different reading directions. This is pretty different from anticipating word shapes that move in one direction along one line.
Smeijers, Fred, Counterpunch: making type in the sixteenth century; designing typefaces now. London, Hyphen Press, 1996