Most adults find it hard to remember the things happened while they were children. Now scientists have found exactly when these memories d.

    A new study has found that most three-year-old children can remember a lot of what happened to them a year e, and these memories are still clear while they are 5 and 6, but by the time they are over 7, these memories become weaker r.

    Most children by the age of 8 or 9 can only remember 35% of their e from under the age of 3 according to the new studies.

    The scientists say this is because at around this age the way we form(形成)memories begins to change. They say that before the age of 7 children do not have a s of time and place in their memories. In older children, however, the early things they can remember become more adult-like in the way they are formed. Children also have a far faster speed of f than adults. The discoveries also help to explain why children can often have clear memories of what they have done, b then forget them just several years later.

    The children were organized to the laboratory for the first time at the age of 3 and discussed 6 impressed(印象深刻的) things from their past, such as the first relaxing trip with your family, the first d accident you met, and the first day of school. The children then returned for a second s between the ages of 5 and 9 to discuss the same things. The scientists found that between the ages of 5 and 7,the amount（量）of memories that the children could remember r between 63%~72%. However, between the ages of 8 to 9, the amount of memories that the children could remember fell to between 35%~36%.