The term for when you write something, but it's through someone else?

When i was on a train in europe, i had a really weird experience. I was writing in my journal, but it wasnt my writing style at all. In fact i felt like i was someone else writing about my excperience (not entirely an out of body experience...but close). There is a term for this, and i was just wondering if anyone knew what it was. It relates specifically to when someone is writing through someone else's perspective. thanks!