The document discusses several models of second language acquisition that consider the role of individual learner differences. It describes models with independent learner variables, such as the Good Language Learner model and Monitor Theory model, which view learner variables as separate from other factors. It also describes models with interdependent learner variables, such as Gardner's educational model and Skehan's model of language learning influences, which see relationships between social, individual, and contextual variables that impact learning outcomes. The document analyzes the strengths and weaknesses of each approach.