So what?<p>Monolinguals have less data to process.  Slower processing is a natural result of having more code to run.  Multilinguals could simply practice quick retrieval if they need to optimize for such a specific environment.  I will gladly trade needing to add that practice, if I would ever find myself with an evolutionary pressure to act quickly and monolingually in such an odd environment as that test, in favor of having multiple analytical frameworks and communication means, which I find extremely well suited for this complex world I find myself in today.<p>For vocabulary size, I would greatly appreciate any interesting correlations.  By itself, it seems like a measure without any use, because number of words and depth of understanding seem unrelated, imho..  Number of concepts and number of connections between concepts... now that seems interesting..  something which multiple languages would actually help :)