To demonstrate the causal role of language, what's needed are studies that directly manipulate language and look for effects in cognition.

WSJ: Does Language Influence Culture?

His experimental research on cognition and language won the Troland Award from the National Academy of Sciences and two prizes from the American Psychological Association.

FORBES: Magazine Article

By requiring speakers to carefully consider the meaning of their words, he hoped that his analytical language would force many of the subterranean quirks of human cognition to the surface, and free people from the bugs that infect their thinking.

NEWYORKER: Utopian for Beginners