The process of language acquisition has some basic requirements. During the first two or three years of development, a child requires interaction with other language-users in order to bring the general language capacity into contact with a particular language such as English. We have already seen, in the case of Genie, that a child who does not hear or is not allowed to use language will learn no language. We have also identified the importance of cultural transmission, meaning that the particular language a child learns is not genetically inherited, but is acquired in a particular language-using environment.

The child must also be physically capable of sending and receiving sound signals in a language. All infants make “cooing” and “babbling” noises during their first year, but congenitally deaf infants stop after about six months. So, in order to speak a language, a child must be able to hear that language being used. By itself, however, hearing language sounds is not enough. One case, reported by Moskowitz (1991), demonstrated that, with deaf parents who gave their normal-hearing son ample exposure to television and radio programs, the boy did not acquire an ability to speak or understand English. What he did learn very effectively, by the age of three, was the use of American Sign Language, that is, the language he used to interact with his parents. A crucial requirement appears to be the opportunity to interact with others via language.