Age seven is when these earliest memories tend to fade into oblivion, a phenomenon known as childhood amnesia, reveal psychologists.
The research involved interviewing children about past events in their lives, starting at age three. Different subsets of the group of children were then tested for recall of these events at ages five, six, seven, eight and nine.
Emory psychologist Patricia Bauer, who led the study, said that their study is the first empirical demonstration of the onset of childhood amnesia.
She said that they actually recorded the memories of children, and then they followed them into the future to track when they forgot these memories.
The experiment began by recording 83 children at the age of three, while their mothers or fathers asked them about six events that the children had experienced in recent months, such as a trip to the zoo or a birthday party.
After recording these base memories, the researchers followed up with the children years later, asking them to recall the events that they recounted at age three. The study subjects were divided into five different groups, and each group of children returned only once to participate in the experiment, from the ages of five to nine.
While the children between the ages of five and seven could recall 63 to 72 percent of the events, the children who were eight and nine years old remembered only about 35 percent of the events.
The study has been published in the journal Memory.