Mark Liberman says on Language Log that he’s been told by a teenager not to end his texts with a period anymore. PhD comics then seems to agree with him.
I think it’s more complicated than this though. Before getting a smartphone, I never ended texts with a period, but now I find myself using one sometimes. How do I decide?
A nonscientific glance through my most recent hundred or so text messages suggests that I use periods after about half of my text messages that could logically have one (i.e. don’t have a question mark or something). There seem to be some patterns.*
I never use periods at the end of location/coordination type texts.
"I’m going to be a few min late"
"K I’m heading down [street name]"
"It’ll prols take me at least 10"
I don’t normally use periods after backchannelling-type responses, but sometimes I seem to do so, for emphasis maybe? They seem more common when someone says something particularly significant or the conversation seems like it might be ending.
Person: “Still can’t believe we have to wait until Thursday for the scene!”
Me: “I know right”
Person: (talking about the pronunciation of a word) “[…]and I keep second-guessing myself”
Me: “Da fuck? No.”
I often use periods (but by no means always, maybe 70% of the time) when I’m telling a longer story, often over multiple texts and using multiple sentences per text. Especially when I’m being snarky.
"Okay. So do I want to go to this show even though I’ll probably be bored? I honestly can’t decide."
"Excuse me, this is internet culture not pop culture. I’m very up on internet culture."
These three circumstances seem to correspond to an increasing formality. Perhaps this reflects the degree to which I’m rushed versus using forethought when texting? I’m especially interested in why I might use periods sometimes when backchannelling but not always.
*Examples are from my own recent textversations, modified to anonymize my interlocutors. I’d love it if anyone replying could give examples of their own texts, as these are very difficult to have enough of to study.