What’s your earliest memory? Chances are you can’t remember anything before the age of three. Otherwise known as childhood amnesia, it affects us all but isn’t quite the stuff of Hollywood. In the movies, the plot usually revolves around someone being bopped on the head and suddenly having no idea who they are or what they are supposed to be doing. And more often than not, a second whack to the head and the person’s memories return, good as new. But is that an accurate depiction of amnesia?