This is a good question. I have to strongly disagree with Nelly on this one. I did it unconsciously (adverb) = I did it without conscious effort, I did it without realising or I did it without thinking about it. To be unconscious (adjective) = to have passed out, to be in a coma, (to be asleep). In British English I haven't heard people use - I did it subconsciously - in the meaning of without conscious effort or in any other context. In my opinion we an talk about our subconscious to describe the deep emotional reactions and psychological traits that people manifest through their actions. I would be interested in hearing other people's ideas on this last point...

The difference can be quite subtle. In informal English both are used to indicate something that occurs without the speaker's full awareness when speaking about perceptions and opinions. Thus they contrast with those things which the speaker is fully aware of. Both words can be substituted in the following: 'Although I did not speak Turkish, I understood his words on an unconscious level' 'She seemed to be subconsciously biased against me' 'Unconscious' is also used to mean 'the opposite of conscious', i.e. asleep or passed out. Thus you could not use 'subconscious' in these sentences: 'An unconscious man was lying in the street' 'Before the surgery, the patient must be fully unconscious' Hope that helps!

unconsciousness is when you've passed out and subconsciousness is when you do something without realizing it or how to say it, kind of not noticing? so yeah, there's a difference. you probably wouldn't be able to use the second phrase ever though since you can't really do much when unconscious.