language learning, generalizing about the usage of new words from similar words that they already know how to use. Language acquisition researcher Michael Ramscar has suggested that when children erroneously expect an ungrammatical form that then never occurs, the repeated failure of expectation serves as a form of implicit negative feedback that allows them to correct their errors over time such as how children correct grammar generalizations like goed to went through repetitive failure. This implies that word learning is a probabilistic, error-driven process, rather than a process of fast mapping, as many nativists assume. In the domain of field research, the Pirahã language is claimed to be a counterexample to the basic tenets of universal grammar. This research has been led by Daniel Everett. Among other things, this language is alleged to lack all evidence for recursion, including embedded clauses, as well as quantifiers and colour terms. According to the writings of Everett, the Pirahã showed these linguistic shortcomings not because they were simple-minded, but because their culture—which emphasized concrete matters in the present and also lacked creation myths and traditions of art making—did not necessitate it. Some other linguists have argued, however, that some of these properties have been misanalyzed, and that others are actually expected under current theories of universal grammar. Chomsky himself has called Everett a charlatan, and other experts have even accused him of purposely ignoring instances of recursion. Other linguists have attempted to reassess Pirahã to see if it did indeed use recursion. In a corpus analysis of the Pirahã language, linguists failed to disprove Everett's arguments against universal grammar and the lack of recursion in Pirahã. However, they also stated that there was "no strong evidence for the lack of recursion either" and they provided "suggestive evidence that Pirahã may have sentences with recursive structures". Daniel Everett has argued that even if a universal grammar is not impossible in principle, it should not be accepted because there are equally or more plausible theories that are simpler. In his words, "universal grammar doesn't seem to work, there doesn't seem to be much evidence for [it]. And what can we put in its place? A complex interplay of factors, of which culture, the values human beings share, plays a major role in structuring the way that we talk and the things that we talk about." Michael Tomasello, a developmental psychologist, also supports this claim, arguing