Multilingual in Bilingual Education Board Posted April 9, 2013 I always thought that my brain got the message that it was not supposed to be using English and as a result, substituted something else, in my case French, that being my other language with any size vocabulary. I only know a smattering of Spanish and German. I bet there is an official name for the phenomenon and that it is well known among people who study how languages are learned. : ) I had a similar experience but with a different background. I grew up bilingual German-English in Germany until I was 11, but then moved to Colorado and spoke exclusively English from that point on (minus the last two years where I've been trying to "recover" my German and pass it on to my kids! :D) By the time I was in high school, I could understand most any German still, but was hard pressed if actually asked to speak it. Nonetheless, I usually spoke German in place of Spanish when I couldn't recall Spanish words. It took us two years to figure that out -- until I got a Spanish teacher who also spoke German -- because I never registered that I was doing it, and my first few Spanish teachers just assumed I was butchering parts of my oral presentations or mis-remembering words. (The latter, of course, was more accurate than they realized!) It was suggested to me that maybe German and Spanish were "living in the same place" in my brain, but that never settled quite right with me, since my German is mainly instinctual (even if weak), just like my English. I really thought it was what you suggested above, Nan, in that my brain just operated on a "not English" mode when I was learning Spanish. Once I realized what was happening, I think I just changed my thinking to "not English and not German," and I no longer had issues with mixing Spanish and German. But I really think that may have only worked because both English and German were so instinctual (I don't really mean that, but don't know what other word to use) for me.