In the late 1950s, the theoretical underpinnings of the method were questioned by linguists such as Noam Chomsky, who pointed out the limitations of structural linguistics. The relevance of behaviorist psychology to language learning was also questioned, most famously by Chomsky's review of B.F. Skinner's Verbal Behavior in 1959. The audio-lingual method was thus deprived of its scientific credibility and it was only a matter of time before the effectiveness of the method itself was questioned.