Think back to your childhood and try to identify your earliest memory. How old were you? Most people are not able to recount memories for experiences prior to the age of three years, a phenomenon called infantile amnesia. The question of why infantile amnesia occurs has intrigued psychologists for decades, especially in light of ample evidence that infants and young children can display impressive memory capabilities. Many find that understanding the general nature of autobiographical memory, that is, memory for events that have occurred in one's own life, can provide some important clues to this mystery. Between ages three and four, children begin to give fairly lengthy and cohesive descriptions of events in their past. What factors are responsible for this developmental turning point?

Perhaps the explanation goes back to some ideas raised by influential Swiss psychologist Jean Piaget—namely, that children under age two years represent events in a qualitatively different form than older children do. According to this line of thought, the verbal abilities that blossom in the two year old allow events to be coded in a form radically different from the action-based codes of the infant. Verbal abilities of one year olds are, in fact, related to their memories for events one year later. When researchers had one year olds imitate an action sequence one year after they first saw it, there was correlation between the children's verbal skills at the time they first saw the event and their success on the later memory task. However, even children with low verbal skills showed evidence of remembering the event; thus, memories may be facilitated by but are not dependent on those verbal skills.

Another suggestion is that before children can talk about past events in their lives, they need to have a reasonable understanding of the self as a psychological entity. The development of an understanding of the self becomes evident between the first and second years of life and shows rapid elaboration in subsequent years. The realization that the physical self has continuity in time, according to this hypothesis, lays the foundation for the emergence of autobiographical memory.

A third possibility is that children will not be able to tell their own "life story" until they understand something about the general form stories take, that is, the structure of narratives. Knowledge about narratives arises from social interactions, particularly the storytelling that children experience from parents and the attempts parents make to talk with children about past events in their lives. When parents talk with children about "what we did today" or "last week" or "last year," they guide the children's formation of a framework for talking about the past. They also provide children with reminders about the memory and relay the message that memories are valued as part of the cultural experience. It is interesting to note that some studies show Caucasian American children have earlier childhood memories than Korean children do. Furthermore, other studies show that Caucasian American mother-child pairs talk about past events three times more often than do Korean mother-child pairs. Thus, the types of social experiences children have do factor into the development of autobiographical memories.

A final suggestion is that children must begin to develop a "theory of mind"—an awareness of the concept of mental states (feelings, desires, beliefs, and thoughts), their own and those of others—before they can talk about their own past memories. Once children become capable of answering such questions as "What does it mean to remember?" and "What does it mean to know something?" improvements in memory seem to occur.

It may be that the developments just described are intertwined with and influence one another. Talking with parents about the past may enhance the development of the self-concept, for example, as well as help the child understand what it means to "remember." No doubt the ability to talk about one's past represents memory of a different level of complexity than simple recognition or recall.

回忆你的童年并尝试找出你最早的记忆。那时你多大？大多数人无法描述出有关三岁前经历的记忆，这种现象就叫做婴儿期遗忘。为什么会发生婴儿期遗忘这个问题已经引发了心理学家们数十年的兴趣，尤其是有大量的证据说明婴幼儿表现出具有令人惊讶的记忆能力。不少人发现理解自传式记忆，即对在某人自己的生活中发生的事件的记忆的一般特性可以为这个不解之谜提供一些重要的线索。3到4岁的儿童开始可以对自己过去经历过的事情给出相当长的具有连贯性的描述。是什么因素导致了这个发育的转折点。

也许对这个问题的解释可以追溯到具有影响力的瑞士心理学家让·皮亚杰，他认为两岁以下的儿童与大于两岁的儿童回忆事件的方式有质的不同。根据这个思路，两岁的儿童发展出的语言能力可以使他们对事件的组织方式与婴儿基于动作的组织方式有根本的差异。事实上，一岁儿童的语言能力与他们一年后对事件的记忆有关。当研究人员让一岁的儿童们在第一次见到一个动作顺序后的一年模仿这个动作顺序，他们能否成功完成这个记忆任务与他们第一次看到这个事件时的语言能力相关。但是，即使是语言能力很差的儿童也显示出了记得该事件的证据，因此，语言能力可以促进记忆，但是记忆并不依赖于语言能力。

另有人提出在儿童能够讲述他们过去经历的事情之前，儿童需要对把自我当做一个心理实体有合理的认识。对自我的认识的发展在1到2岁之前非常明显，并在随后的几年中显示出迅速地细致化。根据这个假说，身体自我在时间上的连续性是出现自传式记忆的基础。

第三种可能是儿童在他们理解故事发生的一般形式，即叙述的结构以前无法描述他们自己的“生活故事”。有关叙述的知识来源于社会互动，尤其是父母给儿童讲故事以及父母尝试跟孩子聊聊孩子们过去经历的事情。当父母跟孩子们说起“昨天我们做了什么”或者“上周”或者“去年”时，他们就会引导儿童形成讲述往事的框架。他们还唤醒了孩子们的记忆，并且向孩子们传达了记忆是文化体验宝贵的一部分的信息。值得一提的是有些研究显示白种美国儿童比韩国儿童的童年记忆更早。此外，其它研究显示白种美国母亲与孩子交流过往的事情的次数是韩国母亲与孩子的三倍。因此，儿童具有的社会经验的类型是发展出自传式记忆的一个因素。

最后一种解释是儿童必须在他们能够讲述自己对过去的记忆前开始发展出一种“心理理论”——对他们自己或别人的心理状态（感觉、欲望、信仰和思想）概念的认识。一旦儿童能够回答诸如“记得是什么意思？”以及“知道某事或某物是什么意思？”等问题的时候，这就会促进他们可能发生的记忆。

可能上面描述的各种发育之间会相互交织并且相互影响。与父母聊聊往事可以加强自我认知的发展，举例来说，就像帮助儿童理解什么是“记得”一样。讲述自己的往事无疑代表了比简单的认出或回忆更为复杂的记忆。