This is a study that I worked on recently as a graduate student, titled Language Learning and Control in Monolinguals and Bilinguals
. We were interested in looking at how bilinguals compare to monolinguals at learning a new language and minimizing interference from their native language. In the study, we taught English monolinguals and Spanish-English bilinguals twenty-four words in an artificial language we invented called Colbertian.
Colbertian was carefully designed to have words that overlapped phonologically with existing English words, so that we could test how much people's English knowledge interfered during a Colbertian language processing task. For example, the Colbertian word for 'acorn' is 'shundoe,' which sounds like the English word 'shovel'. We tracked participants' eye-movements and mouse-movements while they listened to Colbertian words and clicked on the corresponding picture from two choices. What we found was that monolinguals were more distracted than bilinguals were when the other picture's English name sounded like the Colbertian word. So when monolinguals had to find the 'shundoe,' (acorn) they looked more often at a picture of a shovel, and as they went to click on the acorn, their mouse cursor veered more towards the shovel.
Bilinguals have had a lifetime of practice suppressing one language to use another, and that skill transferred to this new task, as they were able to focus on Colbertian and prevent their English knowledege from interfering, whereas monolinguals could not. This ability to prevent interference is important when you're just learning a new language, as the new words' novelty makes them more susceptible to interference from your dominant language. The fact that bilinguals were able to manage that interference helps explain why they tend to be better at picking up third or fourth languages later in life.
If you're interested in learning more about Colbertian, we've designed an interactive online experiment: http://comm.soc.northwestern.edu/bilingualism-psycholinguistics/colbertian/
The original study was published in Cognitive Sciencehttp://onlinelibrary.wiley.com/doi/10.1111/j.1551-6709.2012.01243.x/abstract
and is available on our lab websitehttp://comm.soc.northwestern.edu/bilingualism-psycholinguistics/files/Language-Learning-and-Control.pdf