Is this an Aspie thing? Or just something lots of NT people do too? I don't know if I'm AS or NT, but...
I do this too. I don't COMPLETELY copy an accent, but like if I'm with someone with a strong English accent, almost immediately I'll have it too-like maybe it's only 30% or 50% of an accent or something, but it's not how I normally speak. I've noticed it with kind of the slower drawl type of speech, and others.
It just happens, it's not intentional at all.
My mom, who I think is totally or mostly NT does this too. She's talked about slipping in to an English accent, and then being embarrassed when she realizes it, afraid the person will think she's making fun of them.
I'm pretty sure not all people do this "instant accent" thing-probably not most. But at least if my mom is any indication, it's not an exclusively AS thing. Very interesting though that from this thread it seems to be common. I wonder why? What it means? When I've given it much though, I've wondered if it's some sort of built-in mechanism to help us fit in with other people better, some language part of our brain copies it for social-fitting-in purposes. But if so, why do I have that naturally, but can't do ANYTHING ELSE very naturally? Whereas some really social people don't seem to do it at all. It would be interesting to find out what's going on!