According to the natural order hypothesis, what is likely to lag behind oral proficiency?

The natural order hypothesis posits that language acquisition follows a predictable sequence, where certain grammatical structures are acquired in a specific order, regardless of the learner's age, first language, or the circumstances of acquisition. It is widely understood that oral proficiency typically develops earlier in the learning process compared to written skills.

Writing ability often requires a deeper understanding of grammatical structures, vocabulary, and the ability to organize thoughts coherently and cohesively in text. This level of reflection and internalization of linguistic rules usually comes after learners have established a fundamental level of oral proficiency. As learners become more confident in speaking and listening, they begin to apply that knowledge to writing, but this process naturally takes longer. Thus, in the context of the natural order hypothesis, writing ability is likely to lag behind oral proficiency as learners progress in their acquisition of the language.