Hakuta and Diaz, addressed the chicken and egg question concerning bilinguals and their reported enhanced cognitive abilities; do children with greater cognitive abilities tend to learn more than one language, or could knowing more than one language contribute to enhanced cognitive ability? They administered a set of non-verbal tests that are designed to measure cognitive ability (Raven's Progressive Matrices) to a bilingual sample of children. From these tests, the results showed a higher correlation with the degree of bilingualism (how proficient the individuals were in each of their languages) of their sample and scores on the test, as well as bilingualism did in fact predict performance (and therefore cognitive ability). However, an important point to note, is that most native bilinguals haven't learnt a second language because they are more intelligent. In most cases, they have grown up in a family where use of the two languages is necessary and therefore it is unlikely that the child's intelligence will allow them to learn the second language.