The most influential factor in bilingual language acquisition is the languages spoken by parents to their children, and the languages spoken by others with whom the child comes into contact. This language exposure is called comprehensible input. In a 1984 edition of "Bilingual Education Paper Series," Carolyn Kessler claimed that "children develop faster in the language which is used most in their environment", which may or may not reflect the language of the surrounding community. However, bilingual acquisition can also be affected by the amount of input, the separation of input, and the stability of input, as well as attitudes about bilingualism.