It is one thing reading academic papers and books about multilingual children, and a very different thing experiencing it yourself when having a conversation with your 4-year-old son.
For example, after a few years of exposure to Turkish and Dutch, he comes up with a sentence such as
Dinozor is nog büyüker dan kamyon.
Thinking about how he combines Dutch and Turkish grammar, it is not difficult at all to see how he arrives at such a funny-sounding but constrained-by-both-languages-therefore-predictable result:
This example is one among many, and analyzing all of his “wrong” utterances became a hobby of mine. I’m not collecting data in a scientific manner, so I’m very much limited by my imperfect memory, but so far, all of such sentences seem to follow some patterns, and each time I was able to realize which rule in which language led to the problematic case in the other language.
I’d also like to examine what’s going on in his brain at the neuronal level while he’s saying such sentences, but my research funding is a bit limited nowadays. Even if I had a big budget, I doubt it’d be possible to discover the underlying mechanisms at such a low level (nevertheless, the reductionist cognitive scientist in me still keeps fantasizing about it).
At higher level, thinking about artificial intelligence, especially about Joshua B. Tenenbaum‘s work (see his lectures, as well as these discussions), I wonder whether some AI, maybe some probabilistic system, would be making such “mistakes”. Wouldn’t it be great if such an AI system, fed with two or three languages, behaved in a similar way, letting us understand human mind better? (Of course, such a nice achievement still couldn’t say much about the neural correlates, but that’s a different story.)
Who knows, maybe when my son reaches my current age, about 36 years later, our understanding will have progressed by leaps and bounds, and the young researchers then will be asking more advanced questions. Until then, I’ll continue to have fun with my son, and confuse his mind (and tongue) with various tongue twisters from various languages.