The Evidence
In one of Shenk’s footnotes on page 94 (“From the cradle,
Yo-Yo was surrounded by a world of music,” his mother recalls. “He heard
hundreds of classical selections on records, or played by his father or his
sister. Bach and Mozart were engraved in his mind.”), Shenk focuses on the
impact sound has on a fetus in utero, or in the womb. He gives an example of a
pregnant mother visiting the lion’s section of a zoo from Giselle E. Whitwell’s
observations, saying that the sound of the roar of lions would be “so intense
she had to leave the scene as the fetus reacted with a strong kick and left her
feeling ill” (p. 286). Many years later, the child would “[react] with fear
when viewing TV programs of lions and related animals” and have to “leave war
movies and concerts because the auditory stimulus caused the fetus to become
hyperactive”. Shenk uses this observation to support the quote/argument that
Yo-Yo Ma had a head start in his musical career; his early exposure to music
even before he was born certainly played a role in his ability to have perfect
pitch. If a human fetus reacts so strongly to sounds, one would think sounds in
the environment have a similar impact on animal fetuses also. Could these
sounds become sign stimuli, especially with how they affect the fetus before
and after birth (focusing on lion example)? If so, would the fetus’s reaction/behavior to it be innate or
learnt? (Chapter 51). Since both genetic makeup and environment status contribute
to the development of animal behavior, how can these sounds be used to the
fetus’s selective advantage? Relate the fetus’s response to sounds in the
environment relate the biological theme of interdependence of nature.
Tracy Lai
(tracymlai@hotmail.com)
Tracy Lai
(tracymlai@hotmail.com)
The advice, “Mozart makes babies smart”, is anything but foreign to new mothers. In his book, David Shenk explains, “the sense of hearing is probably the most developed of all the senses before birth” (286). Being one of the first developed senses, sound is definitely a source of stimuli—although not necessarily sign stimuli. Sound stimulates the developing brain of the fetus—either positively or traumatizing. The fetus responds to sounds by increasing its heart rate. A study in the Music Educators Journal concluded the change in heart was positive since it was linked to more sound imitation and earlier vocalization—but it can also make a baby uncomfortable, and have traumatizing consequences like the lion example (http://pregnancy.more4kids.info/336/effect-of-music-on-the-fetus/). Sounds affect the fetus before birth by enhancing neural connections. Babies are born with 100 million nerve cells, and each experience helps establish and strengthen neural connections in the brain (http://www.tinylove.com/index.aspx?id=4193&itemID=6657&text=&returnUrl=%2Fall_articles.html). The phenomenon of exhibiting a similar reaction to stimulus before and after birth could be chalked up to what David Shenk also calls, “long-term memory” (286). When the baby first hears the sound, a neural connection is established. In the example of the lion roar stimulus, the fetus must have established long-term memory in which connections within the cerebral cortex are made permanent (Campbell 1079).
ReplyDeleteAlthough the stimulus of the lion’s roar contributed to long-term memory before and after birth, it is debatable whether it is sign stimulus. A sign stimulus is associated with a fixed action pattern. A fixed action pattern is a series of unlearned acts that is unchangeable and carried to completion once initiated (Campbell 1121). This would imply that the child in the lion example would fear lions for the rest of his life. That would be unlikely since behaviors such as the child’s fear of lions would be subject to learning—such as habituation. Habituation is the loss of responsiveness to a stimulus (Campbell 1125). Dr. Jan Nijhuis of the Maastricht University Medical Center in the Netherlands performed a study to test the effects of repeated stimuli. He found that, “A normal fetus, of about 30 or 32 or 34 weeks, would stop responding after [about] 13 or 14 stimuli” (http://www.livescience.com/5585-fetuses-memories.html). Thus, the lion example would be unlikely to be a fixed action pattern as the child grows older and have repeated stimuli of lions. The child would then learn through habituation and form a new memory.
As the preceding paragraph talks about learning through habituation, the answer to whether the fetus’s reaction is innate or learnt is this: the fetus’s reaction is learnt. By definition, innate behavior is developmentally fixed behavior. The lion example is not the case since as Dr. Jan Nijhuis points out the importance of habituation. Thus, the lion example is a form of learning—a behavior that is variable depending on experience and environment (Campbell 1125). The child was not meant to inherently fear lions; rather, it was the environment the mother was in and the child’s genes (GXE) that influenced the child’s behavior.
The sounds can be used to the fetus’s selective advantage since it stimulates brain activity. The fetus can practice memory and building neural connections. By building a connection to classical music when the baby is still a fetus, the baby could later on recognize the rhythm and be soothed by the familiar music. On the other hand, registering a terrifying lion roar can distress the child, causing the child to have psychological consequences which are not selective advantages. But, it does teach the child to recognize what she or he does not like and to avoid danger associated with the stimuli. Furthermore, the lion roar that made the fetus kick its mother can still be a selective advantage—by communicating to its mother of its distress, the mother can then learn to avoid loud sounds like the lion roar for the remainder of her pregnancy.
ReplyDeleteThis topic displays the theme of interdependence in nature. The interaction of the environment and genes in the fetus that contributed to memory development and learning was caused by an outside stimulus (lion’s roar). The exchange of stimuli and reactions is the foundation of learning; each individual needs an environment that stimulates and influences its development. In this case, the lion provided the environment. Whether the child liked it or not, the lion’s roar triggered the child’s long term memory by promoting more gene expression involved in formation of that neural connection.
~Linda Xu (lindaxu22@hotmail.com)