Why do children generally forget all their memories from before the age of three or four? — E. Lawrence Langan III, Wynnewood, Pa.
Paul Reber, a psychology professor at Northwestern University, answers:
OUR INABILITY to remember many of our early experiences is a phenomenon known as childhood (or infantile) amnesia. Exactly why we forget these memories remains a mystery, although two hypotheses put forth possible explanations.
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The brain systems that support our memory of experiences—the hippocampus and medial temporal lobe—appear to function reasonably well by the end of the first year of life. Infants and toddlers can remember such things as receiving a gift from a favorite uncle or breaking a beloved toy. After early childhood, however, these memories fade or disappear.
One idea is that the brain's prefrontal cortex may not contribute adequately to memory formation at young ages. A recollection of an event consists of a number of pieces of information that, when tied together, create a full picture. Across all ages, we try to summon a memory by using an initial bit of information (a “retrieval cue”) that helps to initiate recall.
Some parts of the memory are not really central to an event, such as where you were standing when you took your first step, but are important for recall. Remembering such contextual information invokes the prefrontal cortex, which develops throughout childhood and even into adulthood. If this part of the brain is not assisting in memory formation early in life, then children may not form vivid, lasting recollections until they are a little bit older.
Another possibility is that our mental representations of the world—the elements from which we form thoughts and memories—change during the first few years of life. For example, it is very likely that learning language during these young years dramatically alters how children see the world. Very early memories from our prelanguage mental representations might become harder and harder to remember as we mature.
Our brain's flexibility and capacity to learn new information and adapt to new experiences are extremely valuable to our survival. It appears that an accidental consequence of this trait is amnesia regarding our early lives. Maturing—putting our childish ways behind us—may cost us our young memories.
Can you make a sociopath—either through brain injury or other types of trauma? —Chris Daly, via e-mail
Jeannine Stamatakis,an instructor at various colleges in the San Francisco Bay Area, explains:
PSYCHOLOGIST John Watson, the founder of behaviorism, once said, “Give me a dozen healthy infants, well formed, and my own specified world to bring them up in, and I’ll guarantee to take any one at random and train him to become any type of specialist
I might select.”
If we take Watson’s logic one step further, it may be possible to mold someone into a psychopath. Psychopathy, also called sociopathy, is defined by a lack of empathy, deceitfulness and complete selfishness. Current thinking is that although certain genes may predispose people toward psychopathy, their environment seems to provide the ultimate catalyst. Thus, a person who possesses the particular genes associated with this malady and is brought up in an abusive or neglectful household will be at a higher risk of exhibiting the traits associated with this disorder.
Severe trauma to specific regions of the brain can cause a person to undergo marked personality changes, such as in the famous case of Phineas Gage. While working as a railroad construction foreman in Vermont in 1848, he survived an accident in which a large iron rod was driven through his head, damaging much of his brain’s left frontal lobe. Although he did not become a sociopath, the reported effects on his personality and behavior were so profound that friends saw him as “no longer Gage.”
An incident two decades ago supports the idea that brain trauma can lead to psychopathic behaviors. In 1991 convicted sex offender Phillip Garrido kidnapped 11-year-old Jaycee Dugard and kept her as a prisoner in his home for 18 years. Experts believe that Garrido experienced severe brain damage after a serious motorcycle accident as a teenager, which was compounded by intense drug use. Garrido’s father said that his son
had been a “good boy” as a child but that he had changed radically after the accident and had become unstable.
Recently neuroscientists have identified areas of the brain related to psychopathic behaviors. Subtle damage to the amygdala, a brain region that helps us process our emotions, may explain why psychopaths act so cruelly and cannot express emotions properly. Psychopathic behaviors are also associated with injury to the cerebral cortex, which regulates memory and self-awareness, and the frontal lobe, which is responsible for self-control and judgment.