What makes memories?

Do you ever wonder how famous people set about writing their memoirs? Did they just sit down and write, pulling all the details out of their vast memory? Or did they have to hunt through their old diaries and documents, trying to piece it all together? Perhaps they paid someone else to do the research.

The question came to mind when I started writing a blog post about children leaving home. It was easy enough to remember waving farewell to my younger daughter as the train taking her to Adelaide pulled out of the station. It was an emotional moment that sticks in my mind. But what year was it? And was my older daughter in Australia at the time, or overseas, and if so, where? For a moment I had a panicky sense of my memory failing me.

By looking through my calendar (I've used an online calendar that forgets nothing for the last few years) and checking the dates on photos, I was able to make some sort of timeline. But unlike my husband, who can probably recall the date of every significant event that ever happened to him, my memory just doesn't serve me well when it comes to dates. I have a few key dates fixed in memory, such as the year I left school, our wedding day, and the births of our children. Beyond that, I have to calculate and guess when most things happened.

Part of the problem with recalling my life is that often I wasn't there at the time. What I mean is, I was physically present, but my mind was elsewhere. I'm a dreamer. Sometimes things going on around me just don't register. I'm always envious of friends who can recall what someone was wearing at a wedding six weeks ago. To me, it's all a pleasant blur. I remember it was a happy day, and not much else. That's how I've always been.

This tallies with what psychologists tell us. The first component of any memory is registration or encoding. Memories have to be processed and laid down from information being received by our brain. Lack of attention, due to personality, tiredness, busyness, or distraction, can all result in memories failing to form. And it's not possible to remember something if your brain didn't register it in the first place.

That's one reason why depression is often associated with poor memory, and the reason why doctors will consider it as a possible alternative diagnosis when they're assessing someone for dementia. Those who are depressed are likely to be too sleep deprived, too distracted and too uninterested to register much of what's going on.

Once a memory has been registered, it has to be stored. This is a complicated process, which is not well understood, but let's just say that not all memories are stored permanently. A lot of information is kept only in our short term memory. Think of shopping lists and telephone numbers - our brains would be swamped if we remembered every detail of our daily lives.

To be transferred to long-term memory information has to be rehearsed - brought back to mind, used, then stored again. Anyone who has tried learning another language will know how important it is to keep rehearsing what has already been learned at regular intervals.

Memories of events also stick better the more we go over them in our minds and tell people about them. Unfortunately we can also elaborate and 'remember' things that didn't happen by the same process. Our memories are also quite open to suggestion.

As with my memory of my daughter leaving home, the more emotional content an event has attached to it, the more likely it is to stay in long term memory. We can remember in detail the birth of a child or the death of a friend 30 years ago, yet forget what we did on Tuesday last week. (Extremely emotional memories may sometimes be supressed, but they're not forgotten.)

Even a bad photograph can bring back vivid memories.
This one instantly reminds me of a fantastic dinner
we had on the waterfront in Cairns.

Finally there is recall or retrieval. Often this is helped by having some sort of cue. I've written before about the "orange on the bed" method of jogging the short-term memory.

One photograph may bring back a wealth of memories of a holiday that we haven't thought about for years. And we've probably all had the experience of a smell suddenly bringing to mind every detail of a long-forgotten place or event. A few days ago, I caught a whiff of rain in the air and was immediately taken back to my years in Albany (where it rained a lot.)

Fortunately I don't think I'll ever need to write my autobiography. Just putting a CV together would be a daunting task. But I'm thankful that these days everything in life seems to be photographed, date-stamped and electronically stored for ever. It gives me a fighting chance of 'remembering' who I am and where I've been.