Other Linguistic Approaches to SLA. Typological and Functional Approaches. Typological Approaches. Stem from study of universals exhibited in languages worldwide. (Greenberg 1963, especially)
Typological and Functional Approaches
If ease/difficulty of acquisition depends on the typology of the language, and not on the discrete language itself, we should see similarities in acquisition patterns across languages with similar typologies.
Mr. Gates introduced me to the man who lives next door to him.
Mr. Gates introduced me to the man who(m) he met last night
Mr. Gates introduced me to the man to who(m) he had given the job.
Mr. Gates intoduced me to the man he bought the car for.
Mr. Gates introduced me to the man whose daughter lives next door to him
Mr. Gates introduced me to a man that he doesn’t have more money than.
(i.e., the verb isn’t inverted unless the question word is also extracted)
(i.e, no inversion in yes-no questions unless there is also inversion in wh- questions)
Yes/no inversion thus most marked among the languages of world, wh-fronting least.
Morphology then spreads to other types of verbs and other aspects, but is dependent on semantics.