Growing up, I always loved languages, and speech. I thought that the different ways people said things, and how many different languages there are in the world was extraordinary. I always felt very lucky to have grown up speaking two languages mostly because I feel that being fluent in two enabled me to understand how languages work better, or as the Lilienfeld text says, I have "heightened metalinquistic insight".
Having spoken both Vietnamese and English at home really let me see how language affects the way that you think, and perceive things because I was able to understand language from an English speaker's point of view, and talk to my parents about how they view things as their most dominant language is Vietnamese. There are a lot of influences that each culture brings to the language. For example, in Vietnamese, you are often more formal when talking to people whereas in English, it's very easy to start talking in a more casual way with someone without coming off as impolite.
What I would like to know though are the effects that people have when they begin to learn more languages, becoming multilingual, and learn more about the cultures behind those languages. How does it affect them psychologically, and how does it change the way they view the world? Furthermore, what makes it possible for people to become multilingual, and to be so proficient in those languages that they make such few mistakes? Along with speaking Vietnamese and English fluently, I've had five years of French courses, and one year of Italian courses, and sometimes I can't even keep them separate!
A few years ago, I watched a documentary called The Boy With the Incredible Brain about a man named David Tammet, a British writer who was diagnosed with Asperger syndrome at the age of 25. As a savant, he once stated that he can speak 9 languages, and in the documentary, he was shown to have learned conversational Icelandic within a week. He is even now currently creating his own language called Mänti! Of course, his situation is a bit different than other people who are multilingual, but his story is fascinating in the sense that you can't help but wonder how his mind must work.
Despite all these questions, if I know one thing for sure, without language, we'd all be lost.