Memories, true and false...

02 December 2007

Interview with

Dr James Ost, Portsmouth University

We've heard about the effect of Alzheimer's on memory, but what actually is memory? How does our brain create a memory, and how can it go wrong?  Dr James Ost, from Portsmouth University tells us more...

Chris - What is memory and how does it work?

James - That's a tough question!  Essentially there are a number of ways you can think about memory.  Some people think of it as kind of store in our head where we put facts and things to retrieve at a later date.  Much like you'd put in books.  Other people think of memory more as a sort of tool we use to help us get around the world.  We use memories or stories to remind us how we got where we are and where we're going next.  There are a number of different ways the psychologists certainly think about memory.  There's not a kind of clear answer to that one, I'm afraid.

BrainChris - Put simply, you take information into your brain and it's in some way converted into connections between nerve cells.

James - You can think of it like that.  That's certainly one way of doing it at a reductionist level.

Chris - When you get the memory back, effectively are those nerve cells recreating or replaying in you brain the sensation that the original experience would have given you? Is that how it works?

James - No.  That's a popular view.  That's referred to as a 'video player' analogy.  In some cases, say if you're retrieving facts or things you've rehearsed an awful lot, then yes indeed it would be like the kind of nerves replaying.  For more complex things like autobiographical memory: memory from episodes in your life and things like this we know that memory isn't a literal replay at all.  In fact, as the previous guest was speaking about in terms of musical memory we know that memories are a kind of reconstructive process.  We fill in lots of gaps as we go along.

Chris - How do you know what we're filling in?  That's a really interesting point, isn't it?  People think that their memory's infallible.  A lot of people think their memory's infallible and we think this is what I remember so it must be true.  How do you work out how much the brain's filling in the gaps for you?

James - You basically have no idea.  They've no clear way of knowing.  Psychologists at the moment are looking at a number of techniques to see if there are any clear markers of what one might call true markers of recall verses or what one might call false recall.  Even at that psychophysiological/cellular level it's almost impossible to distinguish these things.  People have looked at people remembering real things and people remembering imaginary things and eventually moved their brain wave if you like: compared the two.  Any differences are very, very short-lived and disappear within a matter of seconds.

Chris - How do you define a false memory?

Car KeysJames - Again, there are a number of takes on that.  The term 'false memory' was coined by one of the fore fathers of psychology, an American guy called William James, way back in 1890.  He was basically making the observation that a lot of us were relating memories that go wrong.  We forget where we put our car keys and so forth.  Real contemporary interest in that phrase, false memory, has only come about in the last 20-25 years or so in relation to cases of recovered memories in abuse or trauma in a child and things like that.

Chris - There's an interesting study I read, James.  About a year ago, scientists in America got a bunch of students and got them to fill in a questionnaire and said they were going to give them feedback on what they got from the questionnaire.  Then they invented the feedback and gave the same feedback to every single student and told them when they were little some strawberry ice cream made them violently sick.  They re-tested them later and a large number who had previously not reported any kind of allergy to strawberry ice cream then said that strawberry ice cream made them ill.  It's almost as if the researchers had planted a false memory. How does that happen?

James - Again, that's interesting stuff.  That kind of research I'm referring to is really at the forefront of research at the moment.  How does it happen?  Well, again what we know is that memory is a constructive process.  It's not just like pressing play on your DVD and everything coming back.  When we're asked to remember something we try to take information we do have to hand: bits of true memory, bits of things we've seen, bits people have told us and we weave these all into a kind of narrative if you like.  When people suggest things like in the study you were referring to that as a kid you got sick eating strawberry yoghurt [ice cream - QED] it's partly woven into your autobiographical memory, your narrative.  There is research that has shown that people are more likely to avoid strawberry yoghurt [ice cream] after receiving the suggestion but again, that is still in its infancy it's very interesting stuff.

Chris - Just to finish off, can you tell us, how does this impact on criminal proceedings? How do we know that someone's account in court is allowable?

James - That really is the $4m question! I think there's a lot of work over the last 5-6 years from the DNA exoneration cases and these are people, a lot of them on Death Row in America, later is turns out that DNA evidence shows they could not possibly have committed the crime.  Researchers have looked back at those cases and found that in 80% of those cases with DNA exoneration the most convincing piece of evidence to the jury was the eyewitness testimony.  That is someone saying, 'yeah it was definitely James, he was there. That's the feller.'  These kinds of memory errors like forgetting your keys or forgetting where you parked your car, all these things really are the minor ones.  They range on a full spectrum all the way up to these cases where people are being wrongfully imprisoned for things they haven't done.  It is an important issue.

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