What does the brain do? It gets a workout, resolving the conflict! It calls on its command system, which directs the processes we use for planning, problem-solving, and other mentally demanding tasks - like ignoring distractions, switching attention, and holding information in mind (sequences of instructions, for example, or linguistical grammars). In the studies mentioned, bilinguists performed better at these tasks and were more efficient at it.
There is reason to believe that the bilingual experience may influence the brain from INFANCY to OLD AGE! Bilingual pre-schoolers were quicker at performing challenging sorting tasks than the monolinguals. The conclusions even apply to those who learn a second language later in life. The higher the degree of bilingualism, the later the age of onset of dementia (a recent UCSD study).
So I began thinking about our daughters-in-law when they were pregnant with our grandchildren. In the early 1990's, there was something called the "Mozart-effect." Dr. Tomatis (French resesarcher) claimed that if a fetus listened to classical music in utero, his brain growth and neural connections would be enhanced. Both daughters-in-law listened to music in-between the demands of their professional lives.
I know that parents of pre-schoolers in N.Y.C. who apply to prestigious private pre-schools (often in excess of $10,000 a year tuition) must interview with their child. In addition, the child must submit essays (I have to assume they are artwork), as well as undergo interviews alone. So, it won't be surprising to me if some day pregnant mothers repeat calculus and physics formulas to their infants in utero. After all, once the child is born, he could scream to clear his lungs, then spew formulas to get a jump on all those other pre-schoolers!
I see a couple of problems with all this scheduling of fetal activities in utero. First, there's NO firm scientific evidence as yet that acoustic stimulation does anything to influence a fetus' creativity, smarts, or development. A mother's voice is apparently enough to stimulate development. Secondly, the child might become a "Type A" personality in infancy, crying for a new Chinese word in-between his cries for milk!
At least there's still hope for old fogies like me, if we sign up for Italian at the Adult Education Center.