I don’t know if it has to do with my personality, mentality or any other *lities, but I do feel more and more differences when I speak Chinese, Shanghainese, English or Swedish. I’d, for example, unconsciously raise my voice level when I speak Shanghainese (if you have travelled to Shanghai, you’ll know what I mean). 
I think here we have a chicken/egg situation: which comes first?
Does personality change language or language personality? (And are mannerisms personality?)
Don’t we have to have a willingness to experiment first before we can experiment?
Edit:
My German-me, my younger-me, my parent-me, my little old lady-me, all aspects of the same personality, even if, as @derekhyang mentions above, we tend to use different muscles to laugh and speak in our various languages. And, boy, do I remember aching muscles from speaking German again throughout a laughter-filled night!
According to one video by noted linguist, Christophe Clugston, personality has to do with the type of booze habitually tipped back by any given language community.
Mr Clugston defines “vodka drinkers” (Eastern Europeans, basically) as being folks who don’t talk much, who don’t easily open up to strangers, but who are as hard as steel, and who will have your back in a crisis.
“Beer drinkers” (Germans, Dutch, Northern Europeans) are vaguely similar - being perhaps a little less tough and a little more approachable.
“Wine drinkers” (French, Italian, Spanish, Portuguese, South Americans) are ('cording to Clug-wisdom) gregarious, sociable, highly approachable, and keen to discuss philosophy with complete strangers.
Oh yes, then there are “Whisky drinkers” - these are Celtic people (apparently Jack Daniels doesn’t cut it for Cluggy) and they don’t (again 'cording to Clug-wisdom) drink often, but when they do, they go totally crazy - so you have to be careful.
So there you have it.
I must be a true polyglot, because I have been known to consume each and every one of the above beverages - on some infamous occasions all during a single session! 
The Clug’s video on this:
Prost!
I am very impressed by the Personality-Booze correlation theory.
According to the recent statistics, beer is the most popular alcoholic beverage in Japan. I don’t know if this fact is related to the personality traits of contemporary Japanese people.
Well, I don’t know of any personality changes but every language has its own “feel”. When I speak English I just “speak”. When I speak Hindi, it feels normal. When I speak Malayalam, which is my native language, it feels like “speaking from the heart”. I do not normally speak in Marathi unless absolutely necessary.
Moreover, if you speak a particular language to a particular person but one day, suddenly, if you decide to speak in different language to the person, it feels strange. For example, I speak in Hindi with my friends and my father; in Malayalam with my granny and mother; in English with my teachers; in Marathi with some random guy on the street (if the situation arises). If I speak in a different language, it feels bizarre.
Well I guess if you are learning a language for example like Japanese and before you started you were a lazy person and then during the process you caught up more and more of their life style and integrated in your on personality , then yes there are chances that a language can help you evolve.Even though as human beings we should all believe that no one is above another because of any characteristic related to race ,nation or religion , there are some major ethnic groups that have features which make them more prolific than others in everyday life.
That is why I believe that we should take advantage of this globalization phenomenon and try to learn more from others and also try to take over any kind of habit or demeanor that we can adopt and that can make us better as individuals and as ‘‘cells’’ pertaining to a society .
So Clugston only sees as people those who drink , eh ? I should tell him a thing or two (oh and by the way Jay, ‘prost’ means stupid in Romanian :))) ).
This is something pertinent I just discovered on Twitter
So we had a discussion recently on a couple of threads about the dominance of English in science. Somebody posted a link to a TED talk, as I am sure a lot of people remember. I posted a link to the talk recently on a Facebook group for professional astronomers to try and see what people’s opinions were. The discussion never really took off, but one Italian guy did post a link to his blog where he discussed this TED talk.
http://luigifoschini.blogspot.it/2013/10/creativity-and-languages.html
I don’t think it is a particularly good blog post, but still it’s relevant to this discussion. He seems to think that Italian is much richer a language than English (based partly on a massive underestimation of the number of words in the English language), and that this means that Italian speakers are more creative, or something like that.
Good series on English
Yeah, I read the blog post. I think that guy shops at one of “buy in bulk” stores… because he must have stockpiles of aluminum foil for his tin hats.
“According to the Italian encyclopaedia Treccani, the words of Italian tongue are more than 2 millions, while there are “only” more than 600 hundreds English words. Therefore, it is clear how sometimes is very difficult to translate the complexity of Italian into the simplicity of English. This generally results in a simplification of the meaning and a loss of contents.”
That´s stupid in so many ways…wow.
I guess that´s what happens when people try to find “rational” arguments to back up an opinion which is based on emotions.
Well… lots of people do that.
Funny thing is… Switzerland has the same problem of “loss of meaning and content” with its laws. Every law must be in German, French, and Eye-tail-yun. They have significant trouble translating the exact meaning across all languages.
They should just man up and make english an official language here and write everything in English. It’s de-facto international language. Jolanda don’t kill me!
I suggested to him on the Facebook thread that his inability to experiences might be a result of his English being at a lower level than his Italian, but I didn’t get a response.
Captcha: second time the charm!
@spatterson “They should just man up and make english an official language here and write everything in English”
Brilliant, then everyone in Switzerland would read laws and translate them in their head into their native language. A professional translator, who´s specialised in translating “law-stuff” is better at translating “law-stuff” than the average Swiss person.
I think it´s hard enough to understand that stuff even in your native language.
Plus English is too simple a language for that kinda thing.
Captcha: first time!
No, the point is that there are more Swiss people that know English than the other 3 languages.
German speaking Swiss know French… but hate it. French speaking Swiss know some German. Italian speaking swiss know German… but everyone knows English. Seems like a valid optimization to me
Yeah, I´ll move to Italy next year in order to experience the richness and complexity of Italian laws.
“No, the point is that there are more Swiss people that know English than the other 3 languages.”
I get your point. I just don´t agree with your conclusion.