I don't know as...

Do you guys want to hear an example of how different dialects of English can be misunderstood, even between native BE speakers? Well, I'll tell ya anyway lol

A friend and I were discussing via email which film to see at the cinema. He asked 'Do you want to see movie A or movie B (can't remember the exact films)?' I replied ' I don't know as I really want to see movie A, but movie B looks good'. He replied that we should see movie A then. I then answered, thinking he had not read my reply properly, that I had said I didn't really want to see movie A and he had misunderstood. He then insisted that I had written that I really wanted to see it.

I then realised, a little to my mortification, that he had understood 'I don't know, BECAUSE I really want to see movie A' whereas in my part of the country, if said in a certain way, that phrase means 'I don't know THAT or WHETHER/IF I want to see movie A.
That different usage of the word 'as' had made the meaning opposite to each of us.

Hope I have explained this right, it's confused me somewhat even trying to explain it properly lol

Oh yeah, I meant to ask, would many other English speakers recognise my usage, or is it simply a thing from my little part of the world?

I'd have thought it meant the same as your friend did.

MaintiensleDroit

Yes, I don't doubt most people would agree and I don't argue his understanding is correct English. Of course grammatically speaking it is definitely much more correct. But it is funny that up until that point I had never had reason to question the usage I had learnt. I think it must be the case that when I have spoken this phrase, my meaning would be understood from the way I said it. Otherwise it would not have taken this long to come to my attention. I am very interested in the structure of languages, especially having learnt ( to a degree) German, so that's why I was quite taken aback at this.

What is your native language by the way?

I understood your sentence to mean what you thought it meant, especially with "but movie B looks really good" providing even more clarification. To interpret it as your friend did, I would have required a comma after "I don't know".

I am familiar with the "I don't know as"="I don't know that" construction -- it strikes me as a little colloquial, but still common enough.