Which theory postulates that a second language is acquired unconsciously?

The Innatist theory posits that language acquisition, including that of a second language, occurs unconsciously. This theory suggests that humans have an innate capacity for language and that exposure to a language triggers this natural ability. According to this perspective, learners pick up a second language through natural exposure and interaction rather than through explicit instruction or conscious memorization of grammatical rules.

This theory emphasizes the importance of input and interaction in a supportive environment, where the learner can absorb the language through context rather than focusing on formal rules of grammar. It aligns with the understanding that much of language learning is intuitive, similar to how children learn their first language, which resonates with the idea that second language acquisition can follow a comparable unconscious process.

In contrast, the other theories provided do not focus on the unconscious nature of language acquisition. Two-way and one-way communication theories primarily address the dynamics of interaction and the sender-receiver model rather than the cognitive processes involved in learning a language. Cognitive theory focuses on the mental processes involved in learning, stressing conscious engagement and the application of strategies rather than the unconscious absorption of a language. Therefore, the Innatist theory is specifically centered on the unconscious aspect of second language acquisition, making it the correct answer to this question.