Researchers and parents alike have long assumed that experiences that occur during infancy are fundamental to both behavioral and cognitive development. Paradoxically, not only do adults typically fail to recall events that occurred prior to the age of 3, but until the middle part of the twentieth century, there was limited evidence of long-term retention during the infancy period itself. By way of example, although acquiring our first words or taking our first steps was undoubtedly monumental at the time it occurred, we have no conscious recollection of achieving these milestones. In contrast, our memories of other important achievements that took place slightly later in development, like our first day of school or the first time we rode a bike without training wheels, often survive the test of time and eventually form part of our autobiography.