Think back to your earliest memory. Perhaps images of a birthday party
or scenes from a family vacation come to mind. Now think about your age
when that event occurred. Chances are that earliest recollection extends
no further back than your third birthday. In fact, you can probably
come up with only a handful of memories from between the ages of 3 and
7, although family photo albums or other cues may trigger more.
Psychologists refer to this inability of most adults to remember events
from early life, including their birth, as childhood amnesia. Sigmund
Freud first coined the term infantile amnesia, now more broadly referred
to as childhood amnesia, as early as 1899 to explain his adult
patients' scarcity of childhood memories [source: Rapaport]. Freud
proposed that people use it as a means of repressing traumatic, and
often sexual, urgings during that time. To block those unconscious
drives of the id, Freud claimed that humans create screen memories, or
revised versions of events, to protect the conscious ego.
More than a century later, researchers have yet to pin down a precise
explanation for why childhood amnesia occurs. Only in the last 20 years
have people investigated children's, rather than adults', memory
capabilities in search of the answer. This research has brought with it a
new batch of questions about the nuances of young children's memory.
For a long time, the rationale behind childhood amnesia rested on the
assumption that the memory-making parts of babies' brains were
undeveloped. Then, around age 3, children's memory capabilities rapidly
accelerate to adult levels.
However, psychologists have discovered that children as young as 3
months old and 6 months old can form long-term memories. The difference
comes in which memories stick around. For instance, it appears that
babies are born with more intact implicit, or unconscious, memories. At
the same time the explicit, or episodic, memory that records specific
events does not carry information over that three-year gap, explaining
why people do not remember their births.
But why does this happen, and what changes take place in those first
years? And if we can form memories as babies, why don't we retain them
into adulthood? On the next page, we'll take a closer look at a baby's
brain to find out the answer.
Memory Encoding in Children
To form memories, humans must create synapses, or connections between
brain cells, that encode sensory information from an event into our
memory. From there, our brains organize that information into categories
and link it to other similar data, which is called consolidation. In
order for that memory to last, we must periodically retrieve these
memories and retrace those initial synapses, reinforcing those
connections.
Studies have largely refuted the long-held thinking that babies cannot
encode information that forms the foundation of memories. For instance,
in one experiment involving 2- and 3-month-old infants, the babies' legs
were attached by a ribbon to a mobile [source: Hayne]. By kicking their
legs, the babies learned that the motion caused the mobile to move.
Later, placed under the same mobile without the ribbon, the infants
remembered to kick their legs. When the same experiment was performed
with 6-month-olds, they picked up the kicking relationship much more
quickly, indicating that their encoding ability must accelerate
gradually with time, instead of in one significant burst around 3 years
old.
This memory encoding could relate to a baby's development of the
prefrontal cortex at the forehead. This area, which is active during the
encoding and retrieval of explicit memories, is not fully functional at
birth [source: Newcombe et al]. However, by 24 months, the number of
synapses in the prefrontal cortex has reached adult levels [source:
Bauer].
Also, the size of the hippocampus at the base of the brain steadily
grows until your second or third year [source: Bauer]. This is important
because the hippocampus determines what sensory information to transfer
into long-term storage.
But what about implicit memory? Housed in the cerebellum, implicit
memory is essential for newborns, allowing them to associate feelings of
warmth and safety with the sound of their mother's voice and
instinctively knowing how to feed. Confirming this early presence,
studies have revealed few developmental changes in implicit memory as we
age [source: Newcombe et al]. Even in many adult amnesia cases,
implicit skills such as riding a bicycle or playing a piano often
survive the brain trauma.
Now we know that babies have a strong implicit memory and can encode
explicit ones as well, which indicates that childhood amnesia may stem
from faulty explicit memory retrieval. Unless we're thinking
specifically about a past event, it takes some sort of cue to prompt an
explicit memory in all age groups [source: Bauer]. Up next, find out
what those cues are
Language and Sense of Self in Memory-Making
Our earliest memories may remain blocked from our consciousness because
we had no language skills at that time. A 2004 study traced the verbal
development in 27- and 39-month old boys and girls as a measure of how
well they could recall a past event. The researchers found that if the
children didn't know the words to describe the event when it happened,
they couldn't describe it later after learning the appropriate words
[source: Simcock and Hayne].
Verbalizing our personal memories of events contributes to our
autobiographical memories. These types of memories help to define our
sense of self and relationship to people around us. Closely linked to
this is the ability to recognize yourself. Some researchers have
proposed that children do not develop self-recognition skills and a
personal identity until 16 or 24 months [source: Fivush and Nelson].
In addition, we develop knowledge of our personal past when we begin to
organize memories into a context. Many preschool-age children can
explain the different parts of an event in sequential order, such as
what happened when they went to a circus. But it isn't until their fifth
year that they can understand the ideas of time and the past and are
able to place that trip to the circus on a mental time line [source:
Fivush and Nelson].
Parents play a pivotal role in developing children's autobiographical
memory as well. Research has shown that the way parents verbally recall
memories with their small children correlates to those children's
narrative style for retelling memories later in life. In other words,
children whose parents tell them about past events, such as birthday
parties or trips to the zoo, in detail will be more likely to vividly
describe their own memories [source: Urshwa]. Interestingly,
autobiographical memory also has a cultural component, with Westerners'
personal memories focusing more on themselves and Easterners remembering
themselves more in group contexts [source: Urshwa].
More detailed explanations exist regarding childhood amnesia. But brain
structure, language and sense of self are its foundation. To learn more
about amnesia and memory, don't forget to read the links below.
Primal Healing
Flying in the face of childhood amnesia research, some people claim to
recall pre-verbal memories and even recollections from the womb. One
form of psychoanalysis, called primal healing, focuses on traumatic
early memories similar to Sigmund Freud's theory of repressed and screen
memories. Primal therapy links people's present pain with the pain of
birth, taking patients back to the memory of their own birth in a
process referred to as rebirthing. However, in spite of anecdotal
evidence, no scientific study has verified the authenticity of these
rebirthing experiences [source: Eisner].
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