According to BBC's "The Secret You," humans do not become self-aware until the age of 18-24 months. This is tested by placing a red dot on children's faces without their knowing, and then seeing if they realize it is there when placed in front of a mirror. If they reach up to their face to investigate the dot they see in their reflection, they are self-aware.
My niece is 17 months. Before today, I thought she was completely self-aware. I know she understands she is looking at a person when standing in front of a mirror, like the boy did at the beginning of the video. She may even realize that it is the same face she usually sees when looking in a mirror, but what does that mean? I'm not sure she'd recognize the red dot on her cheek right away like the 22 month old girl did. I took the below picture with my niece about a month ago on my computer, so she was 16 months. Right when she saw our faces come up on the screen, she waved. She knew she was looking at people's faces, but she probably didn't understand it was her own.
Before becoming completely self-aware, babies are constantly experiencing and learning new things. So, if we become self-aware around 18-24 months, what are we before then? Do babies carry out ideas without knowing how they do it? Do they think of the desired result, like playing with a toy, and their body simply takes care of the walking and picking it up without them realizing? I would love to know how a baby's mind works, because I don't quite understand how we can even function without knowing we are our own "self".
And self-awareness goes hand in hand with memory, I believe. My earliest memory was getting my pet dog when I was just under 2 years old, and I don't think it's a coincidence that that falls under the period where one becomes self-aware. I don't think you can have one without the other. So, I could argue that my life didn't truly start as a full-fledged, self-aware person until I was 2, right?