Even with all the research surrounding early childhood, there aren't definitive answers as to when -- exactly -- we lose the memories of being a baby. Even among your circle of friends, there are likely to be those who can remember childhood experiences more vividly, and from an earlier age, than others.
One intriguing hypothesis is that the ability to remember being a baby may be linked to left- and right-handedness. A study published in the journal Neuropsychology suggested people who perform tasks with both the right and left hands may be able to remember childhood memories formed at an earlier age than those who are solely right-handed [source: Winerman] .
In the study, about 100 collegiate participants who were mix-handed (ambidextrous) or right-handed were asked to write down two memories from early childhood. They were instructed that one memory should be an event they personally remembered, while the other should be an event retold to them by their parents or another witness, which would later be verified as true. The exercise, designed to measure semantic and episodic memories, revealed the mix-handers' personally remembered (episodic) memories were recalled from an earlier age than the right-handers memories. In addition, mixed-handers could retell memories retold to them from an earlier age, too. The suspected reason? Mixed-handers may have more communication between the brain's hemispheres [source: Winerman].
The corpus callosum, a nerve bundle that connects the two sides of the brain, becomes functional at age 4 or 5. At about that same time, childhood amnesia begins to disappear as episodic memories become encoded on the left hemisphere of the brain and retrieved from the right. (Semantic memories are both encoded and retrieved in the left hemisphere.) The study hypothesized that the increased communication between the right and left brain could allow mix-handers to encode and retrieve early memories more efficiently than right-handers, and that they may have a thicker corpus callosum to boot [source: Winerman].