The case of Laura (also known as Marta), a young retarded woman with a testable IQ of 40, provides the opportunity to address key issues concerning the relationships between language and other mental functions as well and among the components of language use. The case shows that language can develop and function in spite of marked, pervasive cognitive deficiencies, and it provides clinical evidence in support of the notion that language is an independent cognitive ability.
Possibly the most in-depth and comprehensive study of selectively intact language done to date, this case counters claims that cognitive, social/interactive, and perceptual factors can wholly account for language acquisition and upholds the notion that language is a highly evolved, specialized human ability driven at least in part by a set of principles seen in no other cognitive domains.
Jeni Yamada presents Laura's provocative performance profile of relatively advanced linguistic abilities alongside significantly impaired nonlinguistic skills. Laura differs from other subjects studied in that her cognitive impairment is particularly marked. In addition, her syntactic and semantic knowledge are more dissociated than previously studied subjects. As the data on Laura unfold, they show that language can emerge and develop despite limited nonlinguistic cognitive abilities, including those hypothesized to be prerequisite for language or to reflect underlying principles necessary for both nonlinguistic and linguistic development. In addition, the case indicates that various components of language are separable and differentially related to nonlanguage abilities.