The Importance of Conscious Attention in Language Learning

How does your first language influence how you learn a second language? The reason for like 90% of the errors that we make when we are speaking or using our second language is most of the time due to influence from the first language. For example, and I've mentioned this before, French people will say they should be saying 'I am not agreeing' instead of 'I agree', because it's just so much easier in French. That can affect the way you learn another language too. So L1, language one, definitely influences language two. How does it influence the way you learning a second language?"