Welcome to Your Child's Brain: How the Mind Grows From Conception to College (36 page)

Since 1993, scientists have attempted to repeat the original experiment on college students, with mixed success. The closest that anyone has come to testing the idea on babies is that preschoolers do somewhat better on cognitive tests after hearing age-appropriate children’s songs. Even then, like the college students listening to Mozart, the effect is short-lived, not long-lasting, and probably attributable to improvements in their mood.

Beyond consonance, infants are open to different tonal structures. Eight-month-olds are equally good at distinguishing changes in Western scales or Indonesian scales, which are quite different once you get past the basic octave-level
similarity. This ability arises around the same time that infants develop the ability to distinguish vowels and consonants of their own language from other languages (see
chapter 6
). Western adults and older children, however, are much better with Western scales. Infants are similarly open to different culture-specific rhythmic structures. Musical capacities are another example of how the brain’s abilities and preferences are tuned to match the local environment during development.

Babies absorb major features of music, like language, well before they can produce it. One example is rhythm and meter. In Kindermusik, a method of early childhood education in music and movement, infants are exposed to rhythm by activities such as being bounced on the knee in time to a simple, repetitive beat. After two minutes of bouncing to every other beat, the baby is more interested in new rhythms of that type, as opposed to rhythms that emphasize every third beat in a waltzlike fashion. The same effect happens in reverse if babies are bounced in a waltz rhythm. So movement influences auditory rhythm perception in infants, and classes such as Kindermusik may enhance the development of culture-specific rhythm preferences.

In the preschool years, additional capacities develop. By age four, children show a good ability to detect different intensities (loudness), followed by frequencies (pitch), and finally tone duration. Intensity and frequency are processed in the earlier-maturing lower auditory system, while duration requires later-maturing structures such as the neocortex. This developmental process depends on experience. In deaf children who receive cochlear implants, the process is delayed by the period of deprivation, even though their rhythm processing is normal. The need for learning may explain why young children have difficulty staying in tune or on rhythm.

Around the same time, children develop an advanced aspect of music processing: key and harmony. As early as age three, children know whether notes are in key, can pick out dissonant notes in a familiar song, and even adjust their pitch to match another singer. At this age, children also can detect harmony between notes played together, an ability that emerges clearly by age six. Key and harmony preference are both refined by music training. Progress in these areas adds up to general musical aptitude, which by age nine reaches a degree of maturity that remains the same throughout life. By then, parents and teachers can get a sense of what kind of musician a child could become. If by that age she’s got a tin ear, perhaps it’s time to reconsider those flute lessons.

As you might expect, many brain structures that reflect musical aptitude have an auditory function. The auditory cortex, which is found in the temporal lobe, below the temporal-parietal sulcus, is a major site of music processing. The auditory cortex is largely found in structures called
Heschl’s
gyrus
and the
planum temporale
, whose sizes stabilize around age seven. The hemispheres seem to be specialized, with a note’s fundamental frequency processed in the left hemisphere and its spectral pitch (the actual frequencies contained in the note) in the right hemisphere.

In adults, the size of these structures is strongly related to musical ability—the largest known structural variation connected with ability in people. Trained musicians, whether professional or amateur, have over twice as much gray matter in anteromedial Heschl’s gyrus compared with nonmusicians. The additional gray matter is active, too; when a tone is played to musicians, they produce characteristic brain signals, found between fifteen and fifty milliseconds after the tone, that are considerably larger than in nonmusicians. At fifty milliseconds, the signal is five times as large in musicians.

These distinctive characteristics suggest that it might be possible to predict musical aptitude based on brain anatomy. To an extent, this is true: the gray matter volume of anteromedial Heschl’s gyrus is related to musical aptitude with a correlation coefficient (called
r
) of about 0.7. This translates to the statement that if an adult has an above-average amount of gray matter in this brain region, odds are about 3 to 1 that he or she is above average in musical aptitude.

PRACTICAL TIP: THE BENEFITS OF MUSIC AND DRAMA

Playing classical music for your kids isn’t likely to help their brain development. But what about having them play music for you?

Music lessons certainly make children better at musicrelated capacities. These improvements can begin as early as age three and continue as children advance musically. A more common question, though, is whether music training makes a child smarter. Psychology journals are filled with studies showing that music lessons predict visual, motor, attention, and mathematical skills. There is one difficulty with many of these studies, though: nearly all of them are correlative. Perhaps the musically experienced people who took these surveys were smarter to begin with. They often come from advantaged families, as parents who fund music lessons tend to be well educated and financially secure.

The psychologist E. Glenn Schellenberg sought to eliminate this variable. He placed advertisements, recruiting families with six-year-olds for free art lessons. They were then split into four groups: standard keyboard lessons, age-appropriate vocal music lessons, drama lessons, or placement on a waiting list for one year (after which they received the promised art lessons). The drama and lessons-deferred kids provided two control groups against which the other two groups could be compared. Music lessons were given at Toronto’s prestigious Royal Conservatory of Music.

The children were given IQ tests before lessons began and then tested again after thirty-six weeks. On average, the children receiving music lessons scored not quite three IQ points higher than the two control groups, which were similar to each other. The differences were spread over categories that included resistance to distractibility, processing speed, verbal comprehension, and mathematical computation. The effect size was modest, d' = 0.35 (see
p. 64
). That is, the average child receiving music lessons scored better on the IQ test than 62 percent of the control children.

Drama classes showed an unexpected, larger benefit: better social adaptation. Children who took drama lessons at the conservatory showed marked improvement on a rating scale for adaptability and other social skills. The effect size was d' = 0.57, so that the average child receiving drama lessons scored higher than 72 percent of children in the nondrama groups. This effect is large enough that you would be likely to notice the change in your own child. Perhaps deliberate practice at inhabiting the character of another person served to improve the performance of brain areas involved in daily social interactions.

In general, practicing any activity is likely to have the strongest effect on the brain capacities that the activity directly requires. Learning to play music does have some ancillary benefits that span a variety of cognitive abilities, perhaps because it trains the brain’s attentional networks or because musical performance calls so many brain regions into action. In the end, the benefits appear to be small—but real.

Compare this with the intrinsic benefits of music for its own sake, such as whether your child likes playing the instrument or will enjoy music more in adulthood. This benefit of musical training goes beyond the utilitarian. Training gives your child access to music at a deeper level and can contribute to a lifelong love of music.

It might be possible to predict musical aptitude based on brain anatomy.

Does experience influence the size of this brain structure? A clue that such a change is possible can be found in the white matter, which contains long-distance connections between distant brain regions. The long-distance connections through the white matter are organized differently in professional musicians than in nonmusicians. If musical training starts earlier in childhood or involves more cumulative hours of practice, these differences are larger. So extended childhood practice seems to result in measurable changes along with the hard-won skills, though it remains possible that children who started with a larger Heschl’s gyrus were more likely to stick with music lessons.

More convincing evidence comes from a prospective study that followed two groups of children for fifteen months in which one group took weekly keyboard lessons, while the other group participated in a school music class involving singing while playing rhythm instruments. There were no differences in brain structure at the beginning of the study, when the children were six years old on average, but by the end, the keyboard group had larger volumes in the frontal gyrus and the
corpus callosum
. Increases in the size of the corpus callosum, which links the halves of the neocortex, are likely to lead to faster communication between the two hemispheres, which should facilitate the production of well-coordinated two-handed movements. For children who later became musicians, the difference in corpus callosum size persisted into adulthood. There was also some increase in the size of Heschl’s gyrus, but it did not reach statistical significance. Longer follow-up may show a practice-based increase in this region as well.

The processing of melodies involves additional brain regions, including the temporal and frontal areas of the neocortex. These regions are critical for tonal working memory, for instance, holding a melody in your head.

Playing music calls into action yet more brain regions, as the musician must generate precisely timed sequences of motor activity. In brain scanning experiments,
activity during sequence learning and production encompasses motor-related regions of the neocortex as well as the basal ganglia and the cerebellum of musicians and nonmusicians alike. These brain structures are necessary for the initiation and guidance of movement. In the case of music, the demands of coordinating auditory experience and fine movement are particularly intense. How this coordination is achieved by the brain is a very active area of research.

The same brain regions, as well as parietal parts of the neocortex, are activated when people listen to musical sequences. The cerebellum is active in both musicians and music listeners, which likely means it is involved in both producing precise timing and processing purely auditory information. Even more brain regions are activated when people hear complex sequences and combinations of notes.

Such widespread recruitment of brain areas is not surprising if we think of the complexity of recalling a musical sequence. Try to remember the following numerical sequence: 1, 1, 3, 5, 8, 6, 6, 4, 5, 6, 5. Doable, certainly, but you’d have to rehearse it in your head many times to get it. But what if those numbers were translated into music notes, like this?

Even a nonmusician can memorize this melody. Add rhythm and harmony, as you probably did without trying if you know the song, and the piece becomes even more complex. A powerful property of music is its capacity to call into action mechanisms for recalling and producing sequences with a rich structure. In this regard, students of music achieve levels of memorization, recall, and technique that are aided tremendously by music’s capacity to guide and organize brain activity. Music provides scaffolding for mental feats that are otherwise hard to attain.