The social evolution of typographical prosody

Like others, I've often noted  analogies between prosody (as modulations of pitch, voice quality, timing, and so on) and text rendering, whether in calligraphy or typography — e.g. "Intonational focus", 4/29/2011; "Prosodic lettering", 5/8/2011; and many other posts about the communicative use of color, font choice, spatial placement, punctuation, and so on. Some aspects of textual prosody are perceptually natural, like size and spatial separation, while others are conventional, like the use of font choices in dictionary entries. And the conventions change over time and space, like capitalization in English.

Attempts by style guides to lock this variation down are roughly as effective as other efforts to limit individual and cultural creativity, and the growth of social media opens up new horizons for orthographic sociolinguistics.

Early this morning, President Donald J. Trump wrote on Truth Social (image) that

Israel and Iran must immediately stop “shooting.” 

And an hour later he added (image):

Both sides, Israel and Iran, are looking to do an immediate CEASEFIRE! Final negotiations on “Peace” are proceeding, subject to ignorance or stupidity getting in its way. The Blockade will remain in place, and in full force and effect, until a “Final Deal” is reached. Things should move quickly. Thank you for your attention to this matter! 

The use of quotation marks in these examples is an example of what Grant Barrett termed "shout quotes". And the president's use of ALL CAPS is also apparently a matter of emphasis, sometimes combined with shout quotes, as in this example from a few days ago (image):

Well, here in the “HOTTEST” Country in the World, in both April AND May, IT'S RAINING JOBS!

The factors leading to initial capital letters (as in "Country" and "World") are less obvious, and also worthy of analysis.

All of these phenomena have been Out There for a while, and not only in the president's posts. But I haven't seen any systematic studies of variation across time, space, genre, and social structure — although modern text-analysis methods are making this increasingly easy.