There has been parallel interest in associations between formal music lessons and nonmusical abilities. Although such associations are often evident, debate remains about their specificity and whether the causal direction goes from music lessons to nonmusical abilities. Children who take music lessons outperform their counterparts without lessons on a variety of cognitive tests, including tests of language abilities and general intelligence (IQ), and these associations cannot be accounted for by group differences in socio-economic status. When adult musicians are compared to equally professional nonmusicians, however, advantages for the musicians are evident most consistently on tests that involve listening.
Because the vast majority of the relevant studies did not involve random assignment to music lessons, it is impossible to infer that music lessons have causal effects that extend to nonmusical domains. It is equally likely that pre-existing differences influence (1) who takes music lessons, and (2) performance on many tests of nonmusical abilities. In fact, evidence that music lessons cause improvements in nonmusical abilities is limited primarily to interventions in childhood that involve intensive training in listening, which may confer some advantages on tests of language abilities. These small and specific effects cannot explain findings showing large advantages for musically trained children in IQ, and in academic achievement even when IQ is held constant.
Rather, the available evidence suggests that high-functioning children are more likely than other children to take music lessons. Moreover, personality variables may be even better than cognitive variables at predicting who takes music lessons. Even associations between music training and performance on listening tests are unlikely to be independent of pre-existing differences. For example, music aptitude (i.e., innate musical ability) is measured with listening tests, and individuals with low aptitude would be unlikely to take music lessons.