Most people don't have any memory of events that occurred before the age of about three; new research suggests these early memories begin to fade at about the age of seven in a phenomenon referred to as "childhood amnesia."
"Our study is the first empirical demonstration of the onset of childhood amnesia," study leader psychologist Patricia Bauer said in an Emory University news release. "We actually recorded the memories of children, and then we followed them into the future to track when they forgot these memories."
Sigmund Freud first came up with the term "childhood amnesia" in order to describe the loss of early memories; Freud thought this occurred because they were repressing inappropriate sexual memories.
"In recent years, however, growing evidence indicates that, while infants use memory to learn language and make sense of the world around them, they do not yet have the sophisticated neural architecture needed to form and hold onto more complex forms of memory," the news release reported.
The team looked at 83 children around the age of three. They had the parents ask their children about six events that had happened in the past few months, such as trips to the zoo.
"We asked the parents to speak as they normally would to their children," Bauer said. "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 start recounting details of the Chuck E. Cheese experience or divert the conversation by saying something like, "Zoo!" She said. The parents would then choose to divert their child's attention to either the pizza or the zoo.
Parents who chose to follow their children's lead in the conversation tended to get more detailed answers.
"This approach also related to the children having a better memory of the event at a later age," Bauer said.
The team asked the same children about the events a few years later. They found the children between the ages of seven and five could recall up to 72 percent of the events while kids between eight and nine could only remember up to 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 said. "The older children remembered fewer events, but the ones they remembered had more detail."
Children are believed to lack the "strong neural process" that stores autobiographic memories.
"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," Bauer said.
