FORENSIC PSYCHOLOGY: THE COGNITIVE INTERVIEW

Police interviews; eyewitnesses; cognition; memory; hypnosis; fabrication

‘Despite the obvious appeal of television police shows, where attractive investigators and their white-smocked laboratory colleagues solve crimes by conducting high-tech computer-assisted analyses of paint samples, cloth fibers, burn patterns, and the like, in fact most crimes are solved by ordinary-looking police who ask victims and witnesses: “What happened?” One of the best predictors of whether police will close a criminal investigation and how the court case will be resolved is the quality of an eyewitness’s report.’[i]

Eyewitnesses are a major – perhaps the major – source of information in criminal investigations. Police officers are trained to elicit as much information as possible from them. Naturally, their training is informed by research in academic psychology. Cognitive psychology is especially relevant, since it is, essentially, the scientific study of thinking. Psychologists working in this area conceive of thought as the operation of the brain’s software. Since we can usually understand a piece of software – on our laptops on phones - no matter how complex, we ought to be able to understand memory processes, too. That, in turn, would help police officers get the best value out of eyewitnesses. Cognitive psychologists have proposed four so-called ‘mnemonics’. You may want to try them out yourself, next time you’re trying to remember where you parked your car or left your hat.

Contextual reinstatement: The officer asks the witness to recall the event just as they witnessed it.[ii] The witness should think about what they were doing at the time – were they on their way out for groceries, or commuting home from work?; what was the weather like?; how were they feeling? Chances are that you’ve used this mnemonic yourself in everyday life. If you can’t remember where you left your phone, for instance, perhaps you try retracing your steps, either literally or mentally, in an attempt to jog your memory. ‘Right,’ you think, ‘I took off my jacket when I came home and I’m sure my phone was in the pocket. I should go check my jacket…’

Recall all: The witness must try to remember everything they can about the crime, regardless of how trivial it seems. Again, you may recognise this strategy from your own experience: how often does recalling some apparently tiny piece of information help us recall entire episodes from our lives that are connected to it? The phenomenon is analogous to finding one thread attached to a loose screw somewhere in your house, following the thread, and finding half of an unravelled jumper at the end of it. At the start of a police investigation, no one knows which details may prove to be important later. Maybe the thread is an important one. Maybe the jumper you find is the one you misplaced last Christmas.

Recalling in different orders: Naturally, witnesses – solid storytellers all - tend to start at the beginning and work their way to the end. As you may know if you’ve ever been interviewed yourself, police officers generally encourage them to do just that. This mnemonic has witnesses reversing the order – starting at the end and working back to the beginning, as in a postmodern novel - or perhaps starting with the crime and working out from there, as certain eccentric souls eat a pizza.

Changing perspective: The officer asks the witness to recall the events not only from their own point of view, but from that of, say, the victim, the perpetrator, or even a second eyewitness. What would those other individuals have seen? Something different from themselves perhaps, and perhaps something that will prove valuable in court.

Each mnemonic requires the witness to look over their own memories again – to ‘re-view’ them[iii] – and scrutinise the record in a new, different way. The hope is that scraps of information that are lost to one mnemonic may be available to others.

Of course, psychologists didn’t just conjure up these mnemonics willy-nilly. Each one has solid theoretical justification. The first two mnemonics - contextual reinstatement and recall all – are derived from the psychological phenomenon called encoding specificity. This is a jargon term for the idea that recall is aided by cues: that is, objects or phenomena in the immediate environment that overlap with the one you are trying to remember. Among other things, encoding specificity explains why you should never revise for an exam under a tree in the sunshine, or on the beach. The test isn’t going to take place there: it’s going to take place in a dull, institutional environment with artificial lighting. Learn the material in a similar environment and you are already a quarter of the way to a pass grade.

The last two mnemonics – different orders and changing perspective – capitalise on another aspect of memory you may be familiar with. They help maximise the number of ‘retrieval routes’. Imagine a memory located somewhere in the high hills of your long-term memory. It’s there all right, but it’s hard to reach. The different mnemonics represent different routes into the hills. Even if one route is blocked, another may be open.

As long ago as 1984, a group of psychologists carried out the first test of the Cognitive Interview. Witnesses viewed a police training film of a violent crime. They were interviewed 48 hours later, using one of three different methods: first, the Cognitive Interview; second, the ‘standard LAPD Police Interview’; third, hypnosis. The standard interview generated notably less information from the eyewitnesses than either of the other methods. The Cognitive Interview generated the most. It gave no increase in ‘confabulated’ material – that is, material that the eyewitness reported mistakenly but which was not actually present in the original film.[iv]

Psychologists went on to develop further techniques to help eyewitnesses remember car number plates. The techniques involved asking the witness

‘to form an image of the scene in which the car appears, then to focus on the rear end of the car, looking at the lights, the bumper and finally the number plate. Witnesses are then asked, did the plate have any special characteristics? Do you think the numbers were high or low? Did the letters or numbers remind you of any words or things?’[v]

These new techniques were also very effective, helping witnesses to remember far more than in standard police interviews.

It may have struck you - as it struck psychologists who watched them in progress - that a police interview is more than just a set of techniques for eliciting information. It is also a social phenomenon: a somewhat solemn one, at that. A police officer, in a position of some authority, trying to get a job done, is trying to squeeze information out of a member of the public who may be feeling overwhelmed, upset, anxious, intimidated. Stressful circumstances are rarely the optimal ones for cognitive tasks. The best police interview would minimise such circumstances.

It would also take into account other processes. We know that small changes to the way a question is phrased can lead to rather large distortions in the witness’ memory. Officers who used the cognitive interview often failed to use it quite as clinically as psychologists intended. There were ‘endemic problems’, including frequent interruptions, use of closed questions, and inappropriate sequencing of questions.[vi]

Later versions of the cognitive interview took all these social effects into account.

Using the Enhanced Cognitive Interview, officers open not by asking questions but by building rapport with the witness. As you can imagine, that helps make the whole scenario less stressful and daunting. Officers then ask the witness to freely recall the event – that is, describe it, in their own words, without prompts. Only then do officers start introducing the four mnemonics we encountered above.

This later version of the cognitive interview seems pretty effective. It seems to produce greater quality and quantity of information than the standard police interview, at minimal cost in inaccurate, confabulated material.[vii] That said, the whole process can be awfully time-consuming and police officers, (unlike cognitive psychologists,) rarely have the whole day to spare. Since they rarely had time to use all the mnemonics, they had to pick and choose. Often, the first to go was the ‘different orders’ mnemonic, which seems to confuse a lot of witnesses. The ‘change perspective’ mnemonic was similar. Some psychologists reported that it didn’t even seem very effective.[viii] According to some police officers, not only was it difficult and confusing to use, but it also led to fabrications. Many never used it at all.

The so-called ‘Modified Cognitive Interview’ omitted the two controversial mnemonics, replacing them with new, motivated, attempts to ‘try again’. Instead of being exposed to fancy and confusing mnemonics, witnesses were simply told, ‘We are getting a lot of information here. But now I would like you to describe the crime to me again, in as much detail as possible, in your own words’.[ix] The Modified interview produced as much information as the Enhanced version, with no increase in confabulation.

Another alternative, shorter, version has witnesses draw a sketch of the scene – quite a good method for reinstating context, without all those time-consuming questions. It also allows the witness to create their own memory cues without interference from the police officer.[x]

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All pictures courtesy of WikiMedia Commons. References provided partly out of academic habit, but also so that you can chase up anything that looks particularly interesting.

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[i] Fisher, Ronald P & Schreiber, Nadja: ‘Interview Protocols to Improve Eyewitness Memory’, in Michael P Toglia, J Don Read, David F Ross & RCL Lindsay(eds): The Handbook of Eyewitness Psychology: Volume I, Psychology Press, 2007, p28

[ii] Brace, Nicky & Troth, Ilona: ‘Memory – Structures, processes and skills’ in Dorothy Meill, Ann Phoenix & Kerry Thomas,(eds): Mapping Psychology, Book 1, Milton Keynes, UK, 2007, pp111-155

[iii] Harrower, Julie: Applying Psychology to Crime, Hodder Arnold, Oxon, 2006, p152

[iv] Geiselman RE, Fisher RP, Firstenberg I, Hutton LA, Sullivan SJ, Astevissian IV & Prosk AL: ’Enhancement of eyewitness memory – an empirical evaluation of the cognitive interview’, Journal of Police Science & Administration, 1984, vol 12, pp74-80

[v] Harrower, Julie, op cit, p153

[vi] Davis Michael R, McMahon Marilyn, & Greenwood Kenneth M: ‘The Efficacy of Mnemonic Components of the Cognitive Interview: Towards a Shortened Variant for Time-Critical Investigations’, Applied Cognitive Psychology, January 1, 2005, p1

[vii] Memon Amina, Meissner Christian A & Fraser Joanne: ‘The cognitive interview – A meta-analytic review & study-space analysis of the past 25 years’, Psychology, Public Policy, and Law, 2010, Vol. 16, No. 4, 340–372

[viii] Boon J, & Noon E: ‘Changing perspectives in cognitive interviewing’, Psychology, Crime and Law, 1, 1994, pp59–69.

[ix] Davis Michael R, et al, op cit, p6

[x] Dando C, Wilcock R, Milne R & Henry L: ‘A modified cognitive interview procedure for frontline police investigators’, Applied Cognitive Psychology, 23, 2009, pp698-716