We come now to the question of what effect bilingualism has on the individual. This has been a topic of empirical investigation for quite some time, and there are literally hundreds of studies in the literature. In this chapter, I restrict the discussion, for the most part, to studies investigating the effects of early bilingualism--that is, bilingualism in preschool children.
The question of the effects of early bilingualism is of more than theoretical interest. It is a pressing practical issue for many people. Parents in an increasing number of families have to deal with the question of whether to raise their children in a bilingual or monolingual environment. In some cases parents who have learned a second language for educational purposes may wonder about the advantages or disadvantages of raising their children bilingually. In many families husband and wife have different first languages and may wish to give their children access to both languages by using both in the home. In other cases the parents may have immigrated to a new country and may want to maintain the language of the old country while at the same time providing the conditions in the home for the children to learn the language of the new country.
How advisable is it to raise children bilingually? What consequences are there to bilingual upbringing? As we have seen, Jules Ronjat ( 1913) reported that his son Louis showed only positive consequences from having been raised in a bilingual, French-German home environment. According to his father, Louis learned to speak both languages as a native-speaking child would--he showed very few signs of interference between languages; nor did his bilingualism have a deleterious effect on his cognitive development. His development seems to have been quite normal and it has been reported