Should we trust our memories? Consolidation and reconsolidation of memory.

Think about a special event from your past. Maybe a favorite trip, a wedding, or when you started your dream job. What do you remember about that day? Do you remember where you were, who you were with, what the weather was like, or maybe even what you were wearing? In psychology we call memories for important and emotionally charged events like these “flashbulb memories” because we often recall them so vividly it is like we took a snapshot of the event. Or so we think. There is a good chance that some part of that special memory you can see so clearly didn’t happen the way you remember it. You are remembering it incorrectly without even being aware. Why does that happen?

 

To make a memory of an event like the one you are thinking about we need to get the information into our memory, store it there, and then be able to get it back out when we need it. If a memory is strong enough it can become part of our long term memory storage.

 

For a long time our standard view of this long term memory storage process was consolidation theory. According to consolidation theory once memories formed in long term memory they are stable. This means each time you remember an event from your past you are recalling the original, stored memory. This theory views our brains like computers. We store memories in our brain’s hard drive, and when we want to think about a memory we open up a file, read the contents, and store it back again.

 

Reconsolidation theory challenges this view that our memories of our past are fixed, and there is research support for this theory from both cognitive psychology and the neurosciences (see this 2009 article in Karim Nader and Oliver Hardt in Nature Reviews Neuroscience for a review). According to the reconsolidation theory of memory each time we pull a memory from our memory storage it becomes unstable and susceptible to change. Just by thinking about that memory we can change the memory itself. As a result, when we send that memory back to the storage vault we are actually storing the modified memory. Each time we recall that memory the process repeats, resulting in small changes in our memory for the actual event. In effect, when we think about an event from our past we are not recalling the original memory, but a memory of a memory. Reconsolidation theory implies that we have some ability to change our memories, which might be of benefit for people who have experienced past traumatic events.

 

Perhaps it is better to think about our memories less like computers and more like that game of telephone we used to play when we were kids. Each time the message is passed down the line it is changed a little until “the car is green” becomes “by far the spleen”. So next time you are arguing with your partner about what you ate on your first date, keep in mind that you both might be wrong.