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Remember When?
The nature of early memory
In This Issue
What do babies remember—and when? Most adults’
earliest memories are of being a toddler or
preschooler. Before the third or fourth year, the
brain isn’t mature enough to store long-term
memories. In addition, babies lack language, and
their memories are not attached to words; they are
not in a format we can access as adults.
Remember this?
There is some evidence, however, of even newborns
having rudimentary memory, say specialists in infant
memory. How do experts know when an infant remembers
something? Research has shown that newborns can
learn to suck on a pacifier at a certain rate in
order to hear a recording of their mother’s voice.
This ability to associate their own actions with a
memory of something they desire allows researchers
to study what babies remember as they grow and
develop.
Dancing mobiles
One classic experiment that demonstrates that babies
do remember events, and can act on these memories,
studies infants lying in their cribs under a
brightly colored mobile. A soft ribbon is strung
between the infant’s ankle and the mobile’s
crossbar. Babies soon learn that the more they kick,
the more the mobile moves as the ribbon pulls it.
They adore watching the dancing mobile, and kick
with vigor to make it move even more.
Researchers wanted to know how long babies would
recall that their kicks make the mobile move. They
found that after one “training session,” infants as
young as 2 months would remember for a day or two,
while a 6-month-old would kick up a storm when
reintroduced to the same mobile as much as two weeks
later.
New and different
Another way in which infant memory is studied is
based on a universal parental observation: babies
love novelty. Infants soon tire of the “same old,
same old” and are driven to seek and explore new
things and experiences.
In order for researchers to determine what is new,
however, babies must be able to recognize, and
remember, what is familiar. Throughout infancy and
childhood, this “recognition memory” continues to
grow steadily. While a newborn may need to stare at
a new stimulus for many minutes in order to
recognize it just a few minutes later, a 6-month-old
can store this information in a few seconds and
recognize the stimulus up to two weeks afterward.
Brainy babies
Researchers are learning more about how memory
develops by going straight to the source: the brain
itself. At the University of Minnesota’s Center for
Neurobehavioral Development, colorful hairnets
threaded with electrodes measure how babies’ brains
react to what they see and hear. Infant brain waves
differ, the data shows, when they see novel, rather
than familiar, objects and faces.
Interestingly, comparing memory development of
infants born to healthy mothers with that of infants
born to diabetic mothers reveals which parts of the
brain make memory possible. Depending on how well a
woman’s diabetes is controlled during pregnancy, her
fetus may experience iron deficiency and other
factors that affect the development of the part of
the brain involved in memory formation. The
differences in development of these two groups of
babies pinpoints the role of this area of the brain
in the ability to form and store memories.
Eight months and beyond
While young babies certainly take in, store, and
adapt to a lot of information, they are not yet
consciously aware of it, researchers say. It’s not
until a baby’s brain has matured to the point that
he or she is capable of conscious, or explicit,
memory—what we generally think of when we refer to
“memory” in adults—that true recall begins to
emerge.
Unlike earlier recognition memory, when an infant
must look at, hear, feel, smell, or taste something
to know whether he has experienced it before, a baby
of 8 months or so begins to remember faces, words,
objects, and other stimuli without reencountering
them with his physical senses. Indeed, as babies
approach their first birthday, they are able to use
experiences derived from one sense to build memories
that draw on another sense. One study explores this
remarkable ability to make connections between the
senses of touch and sight. After feeling (but not
seeing) 11 different wooden geometric shapes,
healthy 8-month-old babies were able to recognize
visual images of the objects they had held in their
hands, but did not recognize images of objects they
had not touched.
Equally thrilling at this age is the mastery of
“object permanence”—a baby’s ability to hold a
representation of an object (or a person) in mind
after it is no longer in view. As parents of older
infants are well aware, playtime becomes
exponentially more fun when babies reach this
point—when they can remember that there’s a toy
hidden under that blanket, or gleefully engage in a
game of peek-a-boo.
Researchers agree that everyday interaction between
babies and caretakers is the ticket to healthy
development of infant memory. Talking to babies,
playing with them, and reading to them provide just
the right amount of stimulation and intellectual
challenge—and babies’ lasting memories.
Sources: Pediatric Research 55 (2004): 1034–41;
Journal of Pediatrics 142 (2003): 575–82; personal
interview with Charles A. Nelson, Ph.D., April 4,
2005.
The Parent Review newsletter publishes the latest
research findings in child development, learning,
and health. Written for expectant and new parents
and the professionals supporting them, The Parent
Review bridges science and parenting to offer the
best and most relevant research-based news. To learn
more, visit www.theparentreview.com.
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