Remember what happened when you were 3 years old?

Studies confirm that most adults can not remember anything that happened before the age of 3 and that it may be because infants don’t have the neural capabilities needed to retain an autobiographical memory. The new study shows we start forgetting our earliest memories around age 7, a phenomenon termed by Sigmund Freud “childhood amnesia.”

Scientists are pretty sure that our prefrontal cortex uses all our sensory input (eyes, ears, nose and mouth) to process experiences, sorts and tags the pieces and connects them by specific associations.  You see grandpa’s house, smell those grandpa smells, hear his voice and taste that cake that he always gives you.

Cue up that memory later – maybe when you see grandpa’s photo – and your brain searches related fragments and assembles them into the memory.

Of course, when you find that cake years later at a little bakery in Prague,  a new memory is connected to the old one. Bringing  up that old memory again refreshes those related bits and the connecting circuits become stronger.

I was reading today about some researchers in Canada that have demonstrated that some young children can remember events from even before age 2 — but those memories are fragile, with many vanishing by about age 10, according to a study in the journal Child Development this month.

I can’t remember anything clearly from before I attended school at age 5. My sons always maintained that after age 10, they couldn’t remember any early childhood memories except for ones that were triggered by looking at photos or videos. That was a revelation.

Their lives were so recorded by me – from the hospital birthing room on – that they had plenty of help with their memories. In fact, they maintain that they can’t really remember those moments and events. They remember the photo and the story that we have told them about it.  “Oh, this is you when you were three and we went to visit Grandpa in Florida.  Remember seeing the alligator in his backyard?”  He does remember. Well, maybe.

Baby me with my sister

The researchers asked children (ages 4-13) to describe their three earliest memories. Then they repeated the exercise two years later with the same children.

Generally, the youngest children (50 aged 4 to 6) were able to remember in the first interview events from when they were barely 2 years old. Their parents verified the events.

But 2 years later, only 5 kids recalled the same earliest memory. The older kids (1o – 13 at the first interview) mentioned the same earliest memory when they were interviewed two years later. Does that mean the older kids memories were better?

Probably not. The memories that remained of those early years when they were 10 were “crystallized” and so were retained.

There are several related theories.  Maybe storing and retrieving memories might require language skills that don’t develop until age 3 or 4.  Maybe children can recall fragments of their early life, but they can’t true autobiographical memories because they don’t have a firm concept of “self” until they are a few years older.

There definitely appears to be different kinds of memories, and they are stored in different place (neural circuits).

The generic memories (your childhood street, the backyard) are background the sets of a movie.  Then you have semantic memories for facts and other information.  Finally, you have episodic memory for the events that occurred.

So why are those earliest memories so weak or unreliable?  The fragments are there. But the neural traces are weak.

Lesson: The memories we revisit as we get older lay down stronger traces.

Caveat: The brain keeps reassembling the fragments and attaching them to new ones, so they do get distorted.

So, unfortunately, most of us will suffer from “infantile amnesia” – the inability to recall those earliest memories.

Read the article on online.wsj.com that got me started on this.

Click for larger illustration