Why are most college level math textbooks black and white only?

Question

Why are higher level math textbooks almost completely black and white? I can't think of any math textbooks on a subject more advanced than calculus that uses colors. Edited to add that the comments by Dave L Renfro and J W include examples of books that do use color. I have to imagine the use of colors has some educational purpose or psychological function, but I can't seem to find studies about it applying to age groups past K-12 (I'd be happy to read if you can point any out to me).

An exception to the presentation of advanced math content with color may be in video format, so there must be some visual appeal to the use of color. I just can't come up with the reason why this is not applied in books, even when printing is not an issue (as with ebooks, for example).

Historically, I imagine it was simply cheaper to print in all black and white and maybe people just prefer what they're used to. But it doesn't explain why even books offered in electronic format would stick to this rule.

From a practical point of view I understand that mathematical concepts don't have associated colors and don't require them (outside, maybe, of coloring results in graph theory and knot theory, where often enough colors are just represented by symbols).

I've heard the argument that colors make work look "unprofessional" or "inelegant" but I'm also questioning why that is, since it can be a largely subjective assessment.

I'm biased because I like using colors. When I take notes or write on the board, I like color coding, highlighting, and in general having quick visual "shortcuts" to find information on the page. I understand this can be distracting for others and I'd like to better understand why.

Any thoughts?

Edits: adjusted the question to say "most" as it is clear there are some counterexamples.

Answer 1

Part of the cost of a printed book is the cost of paper, printing, and binding (PPB). These costs can be lowered with economies of scale when you are printing a lot of copies. Many of the costs are basically costs to set up for a run, while the incremental cost of printing one more book is small. (This is for traditional printing, not print-on-demand.) Upper-division and graduate books don't sell a lot of copies, so their PPB costs will be much higher for the same design. Many of these books, especially graduate texts, are probably unprofitable for the publisher and author, or the margin may be very tight.

Part of PPB costs is printing, and the cost of printing is proportional to the number of colors of ink used, which is four for a full-color book. That's a lot more money.

Historically, I imagine it was simply cheaper to print in all black and white and maybe people just prefer what they're used to. But it doesn't explain why even books offered in electronic format would stick to this rule.

Most books these days are offered both in print and electronically, so this actually makes printing costs more of an issue. Let's say in the past you would have produced 3000 copies of a printed graduate text in one printing, at cost X. Today, if 2/3 of the students are either buying an electronic text or getting a copy from Library Genesis, then maybe you print 1000 copies, but the production cost is still roughly X, because most of the costs are setup costs. So now production costs are almost three times higher in proportion to the sticker price.

Producing a book with a fancier layout also incurs more costs for design, and if you want to include photos then there are royalties that the publisher has to pay to the photographer for each copy of the book. For a low-selling, unprofitable upper-division book, these costs just make it even more unprofitable.

Answer 2

Use of color definitely can be helpful in learning mathematics. Presentation matters. I have given up on texts using an awful font: if learning the idea requires 95% of my brainpower, and deciphering the bad presentation uses up 10% of my brainpower, it makes the difference between learning and not learning.

That said, using color intelligently requires work and careful thought. Visual design is a different skill from straight pedagogy. I imagine some authors simply do not want to put in the extra work of deciding how to arrange colors. Certainly just formatting math for my workbook was so exhausting I wouldn't have wanted to add the extra labor of formatting for colors too.

When I self-published a physics workbook, the cost of printing color was much higher than black and white. That will sometimes make a difference; I wanted to use color but only in a few spots, so I sacrificed that to keep the books cheaper. As for ebooks, they could use color, but again, you have to put in extra effort to have two versions, one black and white for printing and one color for e-publishing.

An important change that is probably in the works is the ability to display a e-text with the user's choice of foreground/text and background colors. This will make a difference for those with vision disabilities. (One of my favorite inventions that I have heard about in recent years is the font designed for dyslexic people!). I had a student with dyspraxia who had to use yellow paper to be able to read their own work.

When working difficult proofs with students, I have sometimes written each line on the whiteboard in a different color. So they could say, "At the start of the green line, why is the first term positive?" and so forth. It was one more timesaver in communication.

Use of color can certainly help, but it requires more work and expense in general.