Ben Crair demonstrates how the use of the period has evolved in the age of texting:
Say you find yourself limping to the finish of a wearing workday. You text your girlfriend: “I know we made a reservation for your bday tonight but wouldn’t it be more romantic if we ate in instead?” If she replies,
we could do that
Then you can ring up Papa John’s and order something special. But if she replies,
we could do that.
Then you should probably drink a cup of coffee: You’re either going out or you’re eating Papa John’s alone.
This is an unlikely heel turn in linguistics. In most written language, the period is a neutral way to mark a pause or complete a thought; but digital communications are turning it into something more aggressive. “Not long ago, my 17-year-old son noted that many of my texts to him seemed excessively assertive or even harsh, because I routinely used a period at the end,” Mark Liberman, a professor of linguistics at the University of Pennsylvania, told me by email. … “In the world of texting and IMing … the default is to end just by stopping, with no punctuation mark at all,” Liberman wrote me. “In that situation, choosing to add a period also adds meaning because the reader(s) need to figure out why you did it. And what they infer, plausibly enough, is something like ‘This is final, this is the end of the discussion or at least the end of what I have to contribute to it.’”
Jess Zimmerman reviews her own messages and arrives at a different conclusion:
Crair is totally right that “sorry about last night” is qualitatively different from “Sorry about last night.” and that “no” is definitely worlds away from “No.” A quick scan of my iMessage buffer, though, turned up punctuated texts including “A fat corgi. Super best.” and “OMG burrito.” Surely these are things nobody can be mad about; the period here is not expressing displeasure. … One [messager] is earnest and puts a lot of thought into everything he says (he feels strongly about a burrito, I guess); one is playful but argumentative (he just dares you to disagree that a fat corgi is best). The fact that they punctuate lends weight to the things they say, even if it’s on the subject of food and pups—or at least, it lends the appearance or tone of weight. … The period is the equivalent of banging your fist on the table for emphasis: A fat corgi is the best … PERIOD.
Eschewing the period, then, is avoiding emphasis, dodging declarativeness. It’s declining to speak with a tone of authority. It is, in short, the text equivalent of uptalk or vocal fry, the speech patterns that young people (especially young women) use to introduce a sense of accommodating uncertainty into their statements.
Meanwhile, Matthew J.X. Malady suggests a way that punctuation could reduce typographic uncertainty in English: inverted exclamation points, like the ones used at the beginning of sentences in Spanish:
When you’re reading a sentence the writer intended as an exclamation, by the time the exclamation point comes in, you’ve already read all the information that was supposed to have received emphasis! When your eyes reach the punctuation, you already know your wife got the big promotion, or the Pittsburgh Pirates finally made the playoffs, and you’ve missed the chance to read the relevant sentence from start to finish for the first time with the appropriate tone. … The punctuation marks in these instances function like pseudo-footnotes, coming in after the fact to tell you: By the way, you should’ve gotten excited about that last thing you just read…