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1 .<-NARRATOR:->Listen to a part of lecture in a psychology class.
1 .<-FEMALE PROFESSOR:->OK. If I ask about the earliest thing you can remember, I'll bet for most of you your earliest memory, would be from about age 3, right?
2 .Well, that's true for most adults… we can't remember anything that happened before the age of 3.
3 .And this phenomenon is so widespread and well-documented it has a name.
4 .It's called childhood amnesia and was first documented in 1893.
1 .As I said, this phenomenon refers to adults not being able to remember childhood incidents.
2 .It's not children trying to remember events from last month or last year.
3 .Of course it follows that if you can't remember an incident as a child, you probably won't remember it as an adult.
1 .OK, so, so why is this? What are the reasons for childhood amnesia?
2 .Well, once a popular explanation was that childhood memories are repressed ... uh, the memories are disturbing so that as adults we keep them buried.
3 .And so we can’t recall them… and this is based on… well—well it’s not based on–on–on the the kind of solid research and lab testing I want to talk about today, so—so let’s put that explanation aside and concentrate on just two. OK.
1 .It could be that as children we do form memories of things prior to age 3, but forget them as we grow older. That's one explanation.
2 .Another possibility is that children younger than 3 lack, lack some cognitive capacity for memory.
3 .And that idea that children are unable to form memories that's been the dominant belief in psychology for the past hundred years.
1 .And this idea is very much tied to two things. The theories of Jean Piaget and also to language development in children.
2 .So, Piaget's theory of cognitive development.
3 .Piaget suggested that because they don't have language, children younger than 18 to 24 months live in the here and now, that is they lack the means to symbolically represent objects and events that are not physically presented.
4 .Everybody get that?
5 .Piaget proposed that young children don't have a way to represent things that aren't right in front of them.
6 .That's what language does, right?
7 .Words represent things, ideas.
1 .Once language starts to develop, from about age 2, they do have a system for symbolical representation and can talk about things which aren't in their immediate environment, including the past.
2 .Of course, he didn't claim that infants don't have any sort of memory.
3 .It's acknowledged that they can recognize some stimuli, like faces.
4 .And for many years, this model was very much in favor in psychology, even though memory tests were never performed on young children.
1 .Well, finally in the 1980s, a study was done.
在20 世纪80 年代，研究终于结束了。
2 .And this study showed that very young children under the age of 2 do have the capacity for recall.
3 .Now, if the children can't talk, how was recall tested?
4 .Well, that's a good question, since the capacity for recall has always been linked with the ability to talk.
1 .So the researchers set up an experiment using imitation-based tasks.
2 .Adults used props, uh, toys or other objects to demonstrate an action that have 2 steps.
3 .The children were asked to imitate the steps immediately.
4 .And then again after delays of one or more month.
5 .And even after a delay, the children could, could recall or replicate the action, the objects used, the steps involved and the order of the steps.Even children as young as 9 month.
1 .Now, tests showed that there was a faster rate of forgetting among the youngest children.
2 .But most importantly, it showed that development of recall did not depend on language development.
3 .And that was an important finding.
4 .I guess I should add that the findings don't say that there was no conncetion, no connection between the development of language and memory.
5 .There are some evidence that being able to talk about that event does lead to having a stronger memory of that event.
6 .But that doesn't seem to be the real issue here.
1 .So back to our question about the cause of childhood amnesia.
2 .Well, there is something called the rate of forgetting and the childhood amnesia may reflect the high rate of forgetting.
3 .In other words, children under the age of 3 do form memories and do so without language.
4 .But they forget the memories at a fast rate, probably faster than adults do.
5 .Researchers have set a standard, sort of unexpected rate of forgetting.
6 .But that expected rate was set based on tests done on adults.
7 .So what is the rate of forgetting for children under the age of 3.
8 .We expect it to be high. But the tests to prove this really haven't been done yet.