I had this same problem in college when I was taking my Tuesday/Thursday Arabic classes (yes, I studied Arabic in college as my foreign language requirement. No, obviously it didn't stick). After spending 1.5 hours of intently reading and writing only Arabic, I found myself having to find an English book to remind myself of which direction I should write my sentences. I couldn't remember what the number three looked like (it looks very much like a backward version of the Arabic four [ ). It was a funny quirk of studying a language with a completely different alphabet and I'm sure I'm not the only one who suffered such effects.
Now that I'm living in an Arabic-speaking country and exclusively teaching English language learners, I'm experiencing a different kind of side effect: English amnesia. And I know I'm not the only sufferer.
The other day, a colleague of mine who is also a native speaker was grading essays written by her tenth-grade students. She chuckled to herself, turned down the music in her headphones(a tactic we've adopted in an effort to drown out the noise of our "office"), and said, "I've forgotten how to spell the word 'stayed.'" She went on to explain that she has been looking at mis-spelled English words for so long that she's actually forgetting how to spell some basic words correctly.
I've noticed that my vocabulary has gone down a few grade levels. I no longer use big words like I used to. You can see signs of this if you look back at some of my blog posts from before we moved. I also have lost the ability to spell words correctly. A feat that can also be observed in many of my post-Saudi blog posts.
It's starting to affect my teaching as well. The other day, I was reviewing story outlines my tenth grade girls had made. They're going to be writing a personal narrative essay in class soon, and I wanted to make sure they were on the right track. I was also checking their spelling to give them a few hints for the big essay-writing day. One of my girls (who is right one grade level if not more advanced) had written the word "pessimistic" in her outline.
I looked at it, cocked my head to the side, and scrawled "pesimistic" in the space next to her word. I totally thought I was correcting her spelling.
It wasn't until I was in the car on the way home, reflecting on my day, when I realized my asinine mistake! WHAT KIND OF TEACHER AM I!? I just instructed a student on how to spell a word incorrectly. A word that, when I thought about, she had probably looked up in the dictionary to begin with. This student already indicates in class that she thinks I'm a bumbling idiot, and now I've given her proof!!
I'm sure there is a name for this phenomenon. I know there's probably a linguistics graduate student somewhere in the world studying this mental lapse right now. I wish they would hurry up and write an article about how to combat this problem, before I lose all credibility as a teacher!!