Cognitive Code Theory is a theory of second language acquisition that merged Chomsky's Transformational Grammar with Carroll's cognitive psychology. It views language learning as a conscious process of acquiring mental control over phonological, grammatical, and lexical patterns through analyzing these patterns as a system of rules. The key principles of Cognitive Code Theory are that learning occurs through cognitive memory structures, language learning should involve meaningful practice, and learners should discover grammar rules inductively. While it emphasized understanding language structure over usage, some criticisms are that it is more of a theoretical framework than a teaching method and ignores other influences on learning like culture, biology, and past experience.