Few adults can remember anything that happened to them before the age of 3. Now, a new study has documented that it’s about age 7 when our earliest memories begin to fade, a phenomenon known as “childhood amnesia.”
For the study, researchers at Emory University interviewed children about past events in their lives, starting at age 3. The children were then interviewed again years later to test their recall.
“Our study is the first empirical demonstration of the onset of childhood amnesia,” said Emory University psychologist Dr. Patricia Bauer, who led the study. “We actually recorded the memories of children, and then we followed them into the future to track when they forgot these memories.”
It’s been long known that most people’s earliest memories only go back to about age 3. Sigmund Freud coined the term “childhood amnesia” to describe this loss of memory from the infant years. Using his psychoanalytic theory, Freud theorized that people repressed their earliest memories due to their inappropriate sexual nature.
But now, research is showing that infants do not have the sophisticated neural architecture needed to form and hold onto more complex forms of memory.
For their experiment, the researchers recorded 83 children at the age of 3, while their mothers or fathers asked them about events they had experienced in recent months, such as a trip to the zoo or a birthday party.
Bauer explained that parents were asked to speak as they normally would to their children, prompting them with questions, such as “Remember when we went to Chuck E. Cheese’s for your birthday party? You had pizza, didn’t you?”
The child might then recount details of the birthday party or divert the conversation to another event, such as a visit to the zoo.
The researchers noted that some mothers might keep asking about pizza, while other mothers would ask about the trip to the zoo.
Parents who followed a child’s lead in these conversations tended to elicit richer memories from their 3-year-olds, according to Bauer.
“This approach also related to the children having a better memory of the event at a later age,” she said.
The researchers then followed up with the children years later, asking them to recall the events that they recounted at age 3. The children were divided into five groups, and each group of children returned only once to participate in the experiment, from the ages of 5 to 9.
While the children between the ages of 5 and 7 could recall 63 to 72 percent of the events, the children who were 8 and 9 years old remembered only about 35 percent of the events, the researchers reported.
“One surprising finding was that, although the 5- and -6-year-old children remembered a higher percentage of the events, their narratives of these events were less complete,” Bauer said. “The older children remembered fewer events, but the ones they remembered had more detail.”
Some reasons for this difference may be that memories that stick around longer may have richer detail associated with them, she said. More advanced language skills also enable an older child to better elaborate the memory, further cementing it in their minds, she adds.
Young children tend to forget events more rapidly than adults because they lack the strong neural processes required to bring together all the pieces of information that go into a complex autobiographical memory, she explained.
“You have to learn to use a calendar and understand the days of the week and the seasons,” she said. “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.”
She uses an analogy of pasta draining in a colander to explain the difference between early childhood and adult memories.
“Memories are like orzo,” she said, referring to the rice-grained-sized pasta, “little bits and pieces of neural encoding.”
Young children’s brains are like colanders with large holes trying to retain these little pieces of memory, she continued.
“As the water rushes out, so do many of the grains of orzo,” she said. “Adults, however, use a fine net instead of a colander for a screen.”
Bauer said further research is planned to find the age when people acquire an adult memory system, which she believes is between the age of 9 and the college years.
“We’d like to know more about when we trade in our colanders for a net,” she said. “Between the ages of 9 and 18 is largely a no-man’s land of our knowledge of how memory forms.”
Source: Emory University