I especially like the comment that picks up the information from the article that psychological experiments in general (one might say science studies in general) have to be reviewed for reproducibility. The article cites some good sources on that issue. "But ultimately, this isn’t about whether it’s better to know more languages or not. It’s about how science is done, and what counts as decent evidence. It’s about the role of outsiders, and whether they’re best-placed to see through the biases that permeate a field, or incapable of judging it on technical grounds. And it’s about how researchers negotiate disagreements of opinion."

For bilingualism as such, I'll mention that my list of languages learned as second languages (I'm a native speaker of General American English who grew up in the United States) is on my Hacker News user profile. My wife (from Taiwan) and I were quite consistent about bringing up our oldest son (born in the United States, brought up partly in Taiwan) as a bilingual native speaker of Modern Standard Chinese (Mandarin) and English. Some of my younger children are less completely bilingual, but all are comfortable with the project of studying other modern languages. Taiwan's history since World War II is quite interesting, because after the Republic of China Nationalist Party of China (KMT) regime regained control of Taiwan at the end of the war, the school policy was that school lessons all had to be taught in Mandarin. But the local people in Taiwan mostly spoke Taiwanese (my wife's native language) or Hakka, cognate but not mutually intelligible Sinitic languages. So the whole postwar generation went to school, from first grade on, entirely in a foreign language. My wife grew up speaking Taiwanese at home and Mandarin at school (pupils were fined if they spoke the wrong language at school) and she now habitually speaks to her older siblings in Mandarin, even though her whole family in that generation are native speakers of Taiwanese. Some of our nieces in Taiwan, essentially all from Taiwanese or half-Taiwanese families, are more proficient in Mandarin than in Taiwanese. The KMT regime succeeded in switching the majority language in Taiwan (also through control of radio broadcasting and movie production in the days of the former dictatorship) and the school pupils learned a lot even when Taiwan was dirt poor despite going to school in a foreign language. And the level of knowledge of English over there is pretty high too--my wife began study of English as a compulsory school lesson at the beginning of junior high, and I think English is now a primary school subject. So bilingualism is perfectly doable, if a country puts its mind to bilingualism. Even language change is possible in just two generations.