Memory: Improving Accuracy of Eyewitness Testimony (Cognitive Interview)

Last topic in memory!  Woo!  Personally, I really like this one – it’s something I actually really want to study in real life, just to see how effective it is.  Once I’ve finished my A Levels, I just might – so keep your eyes peeled.  Actually, now is probably a fairly good time to mention that whilst I’m not going on to study Psychology at university, I am going on to study Anthropology, and the two subjects are obviously intrinsically linked – so I’ll probably make a blog for that in around August, so keep an eye out for that, if you’re interested.

Now, onto the topic at hand!  As the last post demonstrated, eyewitness testimony isn’t always strictly accurate – but it is usually necessary.  That means that we have to figure out ways of improving it – and what better way than the cognitive interview?

(This is where the ‘about’ widget will be relevant in about five years, and someone will step forward and say “actually, there are many problems with the cognitive interview, which is why we use mind-deep meditation and informative hypnosis, combined with alcohol, to make sure things are as accurate as possible.  I learned this in class.”)

The cognitive interview has four main components to it, all of which aid memory in some way.  Let’s go through them all in order, for the sake of ease (for me).

The first one is mental reinstatement of original context.  This is to help a person remember exactly what they were doing and where they were when whatever happened happened.  That’s things like asking the witness to recount exactly where they were, what they had been doing before, what the time was, how they felt, what they could see, what they could hear and what the weather was like.  This links us back to retrieval failure: these pieces of contextual information can act as important cues to other information that might be crucial to the investigation.

The next step, Report Everything, is also based on the idea of ensuring that someone is given the cues that allow them to access important information.  I’m sure that you can sort of guess what it entails from the title, but I’ll explain anyway.  Report Everything is when a witness is asked to give information on every detail of an event, even if it doesn’t seem important.  This could be something like “my bag split” or “the person I was with tripped” or even something as trivial as “I coughed”.  This is because memories are interconnected, and so remembering one trivial detail, or a partial memory of spilling a carton of milk earlier that day (for example), might cue a full picture of the incident as it occurred.  Again, this is to counteract the effects of retrieval failure.

The next step isn’t so much to do with cues, but with removing the effects of someone’s schema of how events should occur.  A schema is a built-in framework in the brain which we compile from experience, and it helps us to navigate new situations more easily.

The first way of doing this is by using ‘change order’, in which a witness is asked to recount the event backwards, in order to remove any automatic preconceptions about how something should happen.  For example, I did this very quickly a moment ago, and remembered that the last time I went grocery shopping, I queued on the wrong side because a lady had done so before me and I didn’t want to confuse things when it came to who should pay first, but then a lot of people came to the queue behind me and ended up filing halfway down the fruit aisle.  If I had been asked to remember this forwards, I would probably say I had queued from the far left, because this is what my schema dictates I should do.

The final step of the cognitive interview is ‘change perspective’, which works for the same reason as change order.  Change perspective asks a witness to recall what the event might have looked like from, say, across the road.  This means that they don’t use their schema or their subconscious to fill in any gaps, and so only key details like ‘blue shirt’ and ‘male’ come into the equation.

A meta-analysis of 53 studies found that on average, the cognitive interview caused a 34% increase in the accuracy of information recall than when standard interviewing techniques were used.  However, this might be due to individual differences: when only individual components of the CI were used alongside a control condition, results were broadly similar across all five conditions.  When ‘report everything’ and ‘mental reinstatement’ were used, recall was higher than in the other conditions.  This suggests that the cognitive interview as a whole is an important method of increasing accuracy of eyewitness testimony.

Leading on from this, it should be noted that the cognitive interview is not really one technique, but a collection of techniques used to enhance eyewitness memory.  As such, its real-world effectiveness is difficult to assess, as many police forces – such as the Thames Valley Police – use only two or three of the steps rather than all four.

It should be noted that the cognitive interview does not guarantee accuracy.  Kohnken found that whilst there was an 81% increase in correct information using the cognitive interview, there was also a 61% increase in incorrect information.  This suggests that the police need to be very scrupulous indeed in their assessment of information gathered through use of the cognitive interview.

Furthermore, the cognitive interview is time-consuming and expensive.  We can’t guarantee that all police forces have the finances to fund training members in carrying out the cognitive interview, and when they need to apprehend a dangerous criminal, they  generally prefer to minimise time taken and do things as quickly as possible.  As such, the use of the cognitive interview is not widespread.

In spite of this, the Cognitive Interview is often very advantageous when interviewing older witnesses, as these are the witnesses who are most likely to struggle with retrieving information, often due to self-confidence issues.  This was evidenced in a study by Mello and Fisher.

And we’re done with memory.  Next up: attachment.

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