Sophistication

Step 3 of interlanguage development:

understanding the nuances of vocabulary and grammar usage and learning to express meaning in a more precise way.

Learners at this stage benefit from more reading and writing. They may become more adept at noticing the differences between their interlanguage and the target language.

Advanced students will reach this phase in lower secondary school.

Bruntt, Karen and Bryanne, Ulla. Handbook for Grammar Detectives, page 25-27.