January 26, 2014
Childhood Amnesia – At What Age Do We Start Forgetting Childhood Memories?
[ Watch the Video: At What Age Do We Start Forgetting Childhood Memories ]
April Flowers for redOrbit.com - Your Universe OnlineMemories are the way that infants learn new information, however, few adults can remember events that occurred before the age of three. According to a new study from Emory University psychologists, these early memories fade around age seven in a phenomenon known as "childhood amnesia."
According to Emory's Carol Clark, the research team interviewed children about past events in their lives, starting at age three. At ages five, six, seven, eight and nine, different subsets of the total group of children were tested for recall of those same events.
“Our study is the first empirical demonstration of the onset of childhood amnesia,” said Emory psychologist Patricia Bauer. “We actually recorded the memories of children, and then we followed them into the future to track when they forgot these memories.” Bauer collaborated with Marina Larkina, a manager of research projects for Emory's Department of Psychology.
“Knowing how autobiographical memory develops is critically important to understanding ourselves as psychic beings,” Bauer says. “Remembering yourself in the past is how you know who you are today.”
Based on interviews with adults, scientists have known for a long time that most people's earliest memories only go back to about age 3. The name "childhood amnesia" was coined by Sigmund Freud to describe this memory loss from the infant years. Freud, using his psychoanalytic theory, made the controversial proposal that people repressed these early memories due to their inappropriate sexual nature.
However, recent growing evidence indicates that, while infants use memory to learn language and make sense of the world around them, they lack the sophisticated neural architecture required to form and capture more complex forms of memory.
Previous studies of childhood amnesia have relied on interviews with adults. The Emory team took a different approach, wanting to document early autobiographical memory formation, as well as the age at which people forgot these memories.
The team recorded 83 children at the age of three, while their mothers or fathers asked them about six events — such as a trip to the zoo, or a birthday party — that the child had experienced in the last six months.
“We asked the parents to speak as they normally would to their children,” Bauer says.
As an example, Bauer gave the following scenario: “The mother might ask, ‘Remember when we went to Chuck E. Cheese’s for your birthday party?’ She might add, ‘You had pizza, didn’t you?’”
The child might recount details of the visit to Chuck E. Cheese, or they might divert the conversation by saying something like, "Zoo!"
Bauer said some mothers would keep asking about pizza, while others would follow the child's request to talk about the zoo. She found that parents who followed the child's lead tended to elicit richer memories from their three-year-olds. “This approach also related to the children having a better memory of the event at a later age.”
The researchers followed up with the children years later and asked them to recall the events they described at age three. The participants were divided into five groups with each group returning only once between the ages of five to nine to participate in the second part of the experiment.
They found that children between the ages of five and seven could recall 63 to 72 percent of the events. Children who were eight or nine years old, however, retained only about 35 percent of the events.
“One surprising finding was that, although the five-and-six year-old children remembered a higher percentage of the events, their narratives of these events were less complete,” Bauer says. “The older children remembered fewer events, but the ones they remembered had more detail.”
Bauer hypothesizes that the difference in retention may be that memories which stick around longer may be richer in detail associated with them, while increasing language skills enable an older child to better elaborate the memory. This would further cement the memory in the child's mind.
Bauer explains that young children tend to forget events more rapidly than adults because they are missing the strong neural processes required to bring together all the pieces of information that make up a complex autobiographical memory. “You have to learn to use a calendar and understand the days of the week and the seasons. You need to encode information about the physical location of the event. And you need development of a sense of self, an understanding that your perspective is different from that of someone else.”
To understand the difference between early childhood and adult memories, picture pasta draining in a colander.
“Memories are like orzo,” she says, referring to the rice-grained-sized pasta, “little bits and pieces of neural encoding.”
Young children's brains are likened to colanders with big holes. They are unable to retain these little pieces of memory. “As the water rushes out, so do many of the grains of orzo,” Bauer says. “Adults, however, use a fine net instead of a colander for a screen.”
Bauer hopes to continue her research by honing in on the age that people begin to acquire an adult memory system. She believes this age to be between age nine and college.
“We’d like to know more about when we trade in our colanders for a net,” she says. “Between the ages of 9 and 18 is largely a no-man’s land of our knowledge of how memory forms.”
Results of this study were published in a recent issue of the journal Memory.