What theory is based upon the assumption that all human languages have the same structural foundation?

The Theory of Universal Grammar is rooted in the idea that all human languages share an underlying structural foundation, despite the outward differences in syntax, phonetics, and vocabulary. This theory, primarily associated with linguist Noam Chomsky, posits that the ability to acquire language is innately programmed in humans and that there are universal principles that govern the structure of all languages worldwide.

This approach suggests that humans are born with an inherent linguistic capability that allows them to learn any language to which they are exposed. By asserting that certain grammatical structures are common across languages, the Theory of Universal Grammar seeks to explain the similarities and the cognitive processes involved in language acquisition.

The other theories mentioned do not focus on this innate structural similarity among languages. The Behaviorist theory emphasizes learning through reinforcement and imitation, while the Social interactionist theory focuses on the role of social interactions and environmental factors in language acquisition. Cognitive theory centers on mental processes and how they relate to language development but does not make claims about universal structures across languages. Hence, the Theory of Universal Grammar stands out for its emphasis on the shared foundations of all human languages.