John B. Carroll, an influential psychologist in the field of educational linguistics, developed a theory about a cluster of four abilities that factored into language learning aptitude, separate from verbal intelligence and motivation. Using these four distinct abilities (phonetic coding ability, grammatical sensitivity, rote learning ability, and inductive learning ability), Carroll developed the MLAT, a language aptitude assessment for adults.
The four ability components are defined as follows:
Phonetic coding ability – ability to perceive distinct sounds, associate a symbol with that sound and retain that association
Grammatical sensitivity – ability to recognize the grammatical function of a lexical element (word, phrase, etc.) in a sentence without explicit training in grammar
Rote learning ability – ability to learn associations between words in a foreign language and their meanings and retain that association
Inductive learning ability
– ability to infer or induce rules governing the structure of a language