2. better classification skills;
3. better concept formation;
4. better analogical reasoning;
5. better visual-spatial skills;
6. better storytelling skills;
7. better semantic development.
Interaction as well as exposure seems to be critical. Children don't usually end up knowing a language just from TV. They need a fluent speaker to talk to. It used to be thought that it was better for the child to master one language well before hearing the other, to avoid confusion, but nowadays most researchers don't believe that. Children's brains have a tremendous capacity to absorb different languages and differentiate them.
In immigrant families, a child may learn only the minority language at home. They may become fully bilingual after they start school and learn the majority language. But a common historical phenomenon is that such children later forget the minority language, or retain only a receptive understanding, without full speaking fluency. There may be many complex psychological and social reasons, such as embarrassment at feeling different from peers. Yet in many parts of the world, such as Scandinavia, Switzerland and India, multilingualism is universal and is promoted naturally both in homes and school systems from an early age.