Why do Indian Americans who normally speak English with an American accent, automatically switch to speaking English with an Indian accent when they talk to their parents?

The simplest answer is Code-switching. I feel that human beings as social creatures want to connect with people at least on some levels to offer a degree of comfort and the simplest way to connect is to speak as though you belong to the same social group as them. Being of Indian-origin and having lived in Singapore for seventeen years, I instinctively switch to an accent that best suits the nature of the conversation. Being an immigrant means identities are more malleable and the best way to identify with a particular group is to speak in a similar way. Being in engineering school (where there are a higher number of Indian scholars from India than I encountered in my schooling in local schools), I realised I spoke with a slight Indian accent, it felt natural to continue with that intonation because it made the other person comfortable as well. In a casual setting with other Singaporeans, Malaysians etc, I feel comfortable lapsing into Singlish ( a mish-mash of chinese dialect, english, malay and slang) with my peers and it happens naturally as well, like a code for the setting. When in a formal setting, I speak normal, unaccented english tending towards the British pronunciation as we have been taught in schools. I believe it boils down to the setting and basically trying to identify with a group (fitting in). However, the effect is lost when the accent sounds contrived and might be misconstrued as belligerence or mockery. Code-switching generally comes naturally to people who identify with multiple social sets, I find myself an Indian and Singaporean in equal parts so I find my tone changing with the setting pretty often.

I get told by Americans that I have no accent at all and I do this accent switching business all the time. There may be all sorts of technical explanations for this but I'll give you the simplest reason why. When I'm speaking to family, in my mind, I'm speaking Hindi. I know I'm using English words but in my head I am speaking the language that ties us together. I kid you not, I even do the head bob!

To start with, how do you define English with 'no accent'? Everybody's got an accent, that is the whole point of calling it an accent. I'm an Indian and this happens to me too. I was living in India for the first 8 years of my life and learned and used very heavily south-Indian accented English since I was living in south India. However, I'm originally from north India and the kind of English we spoke at home was again very heavily accented, but in a north-Indian way. After those 8 years of my life, I lived in the middle-east and picked up all sorts of accents. Then, I moved to Singapore for higher studies and picked up the accent of English spoken here and the English I speak now has a very indefinable mix of accents. Since I grew up at home speaking one accent, I involuntarily switch to that one when talking to my parents. When I talk to my south Indian friends, I switch to yet another and when talking to my north Indian friends, it turns into yet another. Since recently, my Singaporean accent has also picked up and a lot of Singaporeans are actually surprised when, after talking to me for a while, they find out that I'm not Singaporean. As for the indefinable accent I mentioned, I use it when talking to someone who has an accent that I haven't picked up. All this is very involuntarily and in fact when an Indian friend asked me why I talk to Singaporeans with a Singaporean accent, I tried voluntarily switching to my regular accent but it felt quite weird.

For me, it has to do with a sense of shared context. For example, take the idiom "right from the horse's mouth", which is used in both American and Indian english. In my Indian accent, and that of my parents, the letter "o" in "horse" is pronounced like the letter "a" in "far"; the "ou" in mouth is pronounced, well, further back in the mouth :-) ; the "th" at the end of mouth is pronounced like the "th" in "Thailand". When I pronounce this idiom that way with my parents, I feel the resonance built up over years of speaking that way with them. (There are various exceptions to this; I don't use Indian dialect patterns that I dislike, such as omitting "about" in "he asked about you"). Whereas if I'm talking to others, I feel better resonance when I use the standard American pronunciation -- also built up over years of speaking that way. The english accent I speak with my parents isn't cut and dried -- it's very fluid and dynamic. When I talk to them about computers or technology, I tend to use less of an Indian accent. When I speak with them about Hindu mythology, I tend to use more of an Indian accent. When I speak with them about psychology, philosophy and spirituality, my accent goes all over the place :-) It's whatever resonates well for me in that moment. I think that the sociolinguistic concept of Register is relevant here: http://en.wikipedia.org/wiki/Register_%28sociolinguistics%29 For me, accent is a part of what shapes the different registers in which I speak with people. My accent has certainly evolved over time. I grew up admiring the voices of many American newscasters, sportscasters and talk show hosts, and that's generally how I've modeled my english accent.

Thanks for asking! I definitely did this. Growing up in the US, I developed two accents of English; one at school/predominantly outside home and one at home with parents. Thanks to Anonymous's post below, I now know I'm bi-dialectal! Being bi-dialectal just stuck because I spoke to my parents the way they spoke to me and spoke to Americans the way they spoke to me. It's definitely to do with assimilation and involuntarily making changes to get along with the group of people you're with. I hardly noticed it as a child and only ended up realizing that I was doing this as I got older. One of the quirks of being Indian American, I guess?

It's more about letting the other person understand what you are trying to say, isn't it? So though we may say tier as tier, a railway official in India understands it as tyre. So anyone who says tier in an Indian railway station either does not know the right pronunciation, or might end up having an attitude problem. Same goes for parents. Indian parents are aware of a very Indian-ised English which in many ways is different from the american, british or any other accent. So a switch has to be made to make ourselves understandable.

I'm an Indian American, born and brought up in the Bay Area, CA and I do that a lot. With people who I originally started speaking to with an American accent, I continue using it. But with people who speak to me in an Indian accent, I subconsciously switch to an Indian accent, which I acquired by listening to people talk. My Indian friends often ask me to talk in my American accent with them, they either think it's cool, or they just want to make fun of it, but either way, it's really weird talking in the other accent with someone who you started talking to in the 1st accent. I guess that's just how I connect to people.

I don't know about Indians doing this, but I believe it's pretty universal.  Actually, one if the funniest things I witnessed were a group of Indians who were born in the US, faking Indian accents.  In normal voices you wouldn't have any idea they were Indian and it was very funny.  Making fun of ones self usually is.