Edward Fisher of the University of California, Los Angeles, and Ronald Geiselman, of Florida
International University, were investigating ways of turning findings from psychological
research, such as the context reinstatement effect, into practical techniques that could
be used in real police investigations. They developed a procedure that they called the
cognitive interview.
The way that police traditionally interview eyewitnesses involves frequent interruptions
by the interviewer, a focus on details relevant to the investigation, and the use of the question-answer
format. As we’ve already seen, one problem with a question-focussed approach is that
there is the opportunity for false memories to be created by leading questions. Edward
Fisher and Ronald Geiselman raided the cognitive psychology literature, including the work
on context reinstatement, to create the cognitive interview.
Here are some of the key ideas behind it. First, memory research tells us that memory
traces are usually complex and contain different sorts of information. Second, research
indicates that the ease with which a memory is recalled depends on how much "informational
overlap" it has with the cues being used to retrieve it. This refers to work on what’s
known as the “encoding specificity principle” by Endel Tulving of the University of Toronto,
amongst others.
When something is remembered, it is encoded with respect to the context in which it
is studied, producing a unique trace which incorporates information from both target
and context. This means that the probability of successfully remembering something depends
on the degree of overlap between the information present at retrieval and the information stored
in memory. That is, the more overlap you can get between a memory of something that
you’ve already recalled and something you want to recall, then the better chance of
retrieving the desired memory. Another finding is that any given memory can be accessed by
a number of different retrieval cues. That is, if you can’t access the memory you want
via one particular cue, then try another.
The cognitive interview uses these principles of memory retrieval to help witnesses maximise
their chances of recalling the events of a crime.
The question is, what’s the evidence that it actually does result in better eyewitness
memory recall than more traditional police interviews? Fisher and Geiselmen tested the
original version of the cognitive interview by recruiting 17 highly experienced interviewers,
all of whom had been trained in forensic hypnosis. This included police detectives, CIA investigators,
and private detectives.
They were randomly assigned to either use the cognitive interview or to use standard police interviews
– as well as other options. Then the researchers got 89 undergraduates
to watch one of four films depicting a violent murder – borrowed from the LAPD training
academy. Forty-eight hours after watching the crime, the students were interviewed by
the professional investigators. These interviews were transcribed and scored.
An exhaustive list of all the details of the crimes that were mentioned was drawn up and
then researchers calculated the proportion of those items mentioned by each of the students.
Doing this, they found that the cognitive interview elicited between 25% and 35% more
information than the standard police interview. So – that’s very promising. As a result
of this early work, Fisher and Geiselmen went on to refine their methods and also to test
them in more realistic situations.
Here’s one example, where they tested the cognitive interview for real police detectives
solving genuine crimes. This time they recruited 16 police detectives based in Florida. In
the initial stage of the study, they recorded and analysed 5-7 interviews by each detective
over 4 months. Then they randomly chose half the detectives and trained them in how to
give the cognitive interview. Then they monitored and analysed interviews conducted by both
the trained and untrained detectives for 7 months afterwards. They eventually amassed
between 2 and 7 appropriate interviews per detective.
All the interviews were transcribed and analysed as before. Of course, one big disadvantage
of studying real crime investigations is that it is much harder to determine what is actually
true or not for the purposes of determining whether the interviews were yielding real
or false memories. The way they did this in this particular study was by comparing what
the witnesses said with another reliable source of information, such as another witness, a
confession by criminal, or from hidden camera footage.
So they only looked at corroborated facts, and this is what they found. So the cognitive
interview, in this real world study looking at real crimes, led to a 47 percent increase
in the number of facts recalled compared with a standard police interview.
There’s since been a large body of research looking at these cognitive interview techniques.
A meta-analysis of some of this work, by Gunter Kohnken of the University of Kiel and his
colleagues confirmed that, over 42 studies, the cognitive interview reliably generates
more correct details than the standard interview. And this effect was greater the more realistic
the context of the study.
The cognitive interview is now routinely taught to police officers in Britain and also widely
used in the US, Australia, New Zealand, the UK, Canada, Singapore, and Hong Kong.
Of course, as we’re taking a scientific approach in this course, we also need to talk about the
limitations of the cognitive interview. Like everything else in life, it’s not perfect.
The cognitive interview is more difficult to conduct than a standard interview, it takes
longer and it requires more effort on the part of the interviewer.
Also, it’s only useful for co-operative eyewitnesses.
It’s very much about improving recall memory, it doesn’t help with recognition memory
- for example recognising a suspect in a line-up. However, taking all that on board, overall
it’s still considered a valuable tool for the investigator – and it’s a great example
of how cognitive psychology research can be successfully applied to the real world.