Do Native speakers change their register when they speak to non-native speakers?
Most do, and maybe it does help the non-native speaker to learn the language. I
personally always made an effort not to speak in these types of registers, because I
found that when I was learning Hebrew, from the age of 13, in the United States, that
when people spoke to me in a simplified way, and then I spoke to Hebrew speakers
who did not speak simplified, it was much more difficult for me to understand the
normal way of speaking, and be understood. It took me a lot longer to unlearn the
false way of speaking. If a person learns the same way all the time, then that person
would not have to go through the unlearning process.
With my children here in Israel, I also did not speak "caretakerese" for the same
reason. My children were exposed to three languages in the home, English, Hebrew
and French. I felt that if I exposed them to "motherese" then that would be another
language. It did turn out that my children did not learn French, but did learn both
English and Hebrew by the age of 3 when they went to gan. They are fluent in both
languages. Did I miss talking in motherese? I don't think so. I felt that I did not have
to change my personality to interact with my children.