Whether or not this particular schema is the correct one, one clear conclusion that can be drawn from this literature is that there is little doubt that children show left hemisphere dominance for much of the language function well before puberty. There is also no necessary relationship between cerebral dominance and second language acquisition ability. As mentioned above, alternative explanations have been proposed for child-adult differences in second language attainment, explanations that are probably unrelated to cerebral dominance. As an example we briefly sketch one possibility.
In Chapter 2 it was hypothesized that certain cognitive and affective changes taking place around puberty, possibly connected to the onset of the stage of formal operations (Inhelder and Piaget, 1958), an event which generally occurs at around age 12, may have the effect of boosting language learning potential, while limiting or weakening the language acquisition potential. This change may be responsible for observed child-adult differences in language acquisition.
At formal operations, the adolescent becomes an abstract thinker, and is able to "reflect on the rules he possesses and on his thoughts" (Developmental Psychology Today, 1971, p. 336). He can, for the first time, "take his mental constructions as objects and reason about them", and can "deal with problems in which many factors operate at the same time" (Elkind, 1970, p. 66).
The meta-awareness and ability to theorize brought about by formal operations allows the learner (or compels him) to create an abstract theory (or grammar) of the language he is approaching. Formal operations may thus allow the "conscious grammar", or