Most of us adults do not remember childhood events occurring before we were three to four years old. What is the reason for this period of childhood amnesia. Current psychologists dismiss Freud’s explanation -- that the memories were repressed because they are too traumatic. But they had no explanation for it. Till now.
Two researchers, Gabrielle Simcock and Harlene Hayne of the University of Otago noticed that the period of amnesia generally ends around the time kids start acquiring language. They devised an experiment to test their hypothesis. And their findings indicate that childhood amnesia may be due to the lack of language skills to encode the memories during those years.
More about the study and the findings here.