Why do you think this research result would be of interest to Less Wrongers? No doubt, memorizing large numbers of false statements would also help your brain "become bigger and increase its activity", but this doesn't seem to be particularly helpful (besides maybe delaying the onset of degenerative diseases of the brain).
Note: I am currently learning both Japanese and Spanish in my spare time.
This article can be used as additional source of motivation for people, who are going to learn foreign language.
Shooting skeet eight hours a month was excellent training for them. It trained them to shoot skeet.
Joseph Heller, Catch-22
Learning new languages does something interesting to your brain if you're the kind of person who's really good at it. What happens to normal people?
Typically, these results (eg. the London taxi driver study) are zero-sum: the overall weight or volume remains constant, and it's other areas that shrink.
/too lazy to read actual paper
I don't think this is actually the case.
Volume or weight don't need to be affected necessarily, it's all in the connectome. However, in the case of hippocampal atrophy there is a significant correlation between size and function, without a trade-off with other important areas. On the contrary, looking at e.g. Korsakoff's syndrome MRI scans, atrophy in one area usually predicts atrophy in other Brodmann areas.
Why would other such areas be affected negatively? Did you refer to neuroplasticity, e.g. when areas get reappropriated, as supposedly with Savants, or deaf people? That's a different - and niche - phenomenon.
OP mentioned nothing about the connectome; to quote:
However, in the language group, certain parts of the brain had grown, including the hippocampus, responsible for learning new information, and three areas in the cerebral cortex.
Further:
However, in the case of hippocampal atrophy there is a significant correlation between size and function, without a trade-off with other important areas. On the contrary, looking at e.g. Korsakoff's syndrome MRI scans, atrophy in one area usually predicts atrophy in other Brodmann areas.
Are you trying to argue about healthy people from diseased people?
Weight and volume are surrogates for the size of the connectome, just not perfect ones (synaptic pruning in adolescence, tumors etcetera).
Healthy versus diseased as a binary choice is too simplistic. While the example I used was indeed of a rather severe disease, it also applies to e.g. elderly brains versus mid-life brains, or kids versus adults.
On any major axis I can think of (age, "diseases"), observing a smaller brain area (also: a loss of neurons) if anything predicts for smaller other brain areas (also: loss of neurons elsewhere). A positive Pearson's r, not a negative one.
Why would other areas shrink? Because cranial capacity is limited? You'd think so, but I've never come across anything of the kind (other than the niche cases mentioned). If you remember this as a typical phenomenon, I'd appreciate the source.
Probably the most important thing to remember from the top link:
“Even if we cannot compare three months of intensive language study with a lifetime of being bilingual, there is a lot to suggest that learning languages is a good way to keep the brain in shape”, says Johan Mårtensson.
helps your brain to become bigger and increase its activity
It seems to be implied that this is a good thing, but why would it be?
http://www.lunduniversity.lu.se/o.o.i.s?news_item=5928&id=24890
According to Johan Mårtensson from Lund University, if you are learning new language quickly, it helps your brain to become bigger and increase its activity:
This finding came from scientists at Lund University, after examining young recruits with a talent for acquiring languages who were able to speak in Arabic, Russian, or Dari fluently after just 13 months of learning, before which they had no knowledge of the languages.
After analyzing the results, the scientists saw no difference in the brain structure of the control group. However, in the language group, certain parts of the brain had grown, including the hippocampus, responsible for learning new information, and three areas in the cerebral cortex.
And there is more:
One particular study from 2011 provided evidence that Alzheimer's was delayed 5 years for bilingual patients, compared to monolingual patients.