Eyewitness Memory
Blandón-Gitlin, I., Fenn, E., & Paquette, K. (2019). True and false memories in forensic contexts. In The
Routledge International Handbook of Legal and Investigative Psychology (pp. 37-55). Routledge.
Introduction
Research has shown that witness memory in forensic contexts can easily be corrupted. This chapter
deals with: key processes and factors that can lead to memory errors, protocols to safeguard against
inducing errors in the investigative process itself, methods to discriminate between true and false
events.
Witness memory: constructed and reconstructed
Most people have misconceptions about how memory works. The majority thinks that memory works
like a video camera, 55% thought memory could be enhanced by hypnosis, 48% believed memory is
permanent and 37% believed the testimony of a confident witness is enough.
Memory does not work like a video camera. Memory is a constructive and reconstructive process.
When someone experiences a complex event, he will only acquire pieces of information from the
environment. These pieces are not enough to form a complete representation, so information from
other sources is used to form the memory (schema’s, information from external sources like other
witnesses or interview questions and making inferences when thinking about the event afterwards).
The result is a memory constructed of combined fragments. The gist of the information in memory is
stable (I was attacked), but the verbatim (actual details) might not be stored or will fade quickly.
Memories are fluid and can change overtime. When witnesses think about the event or answer
interview questions, the event is reconstructed. If something they recall does not fit with the current
story, this piece will be removed and new information will be integrated to make sense of the event.
This makes a memory fundamentally different from the original event.
The degree of reliability depends on different factors, the decisions investigators and legal
professionals make about how to process the memory evidence has a great effect.
Memory for traumatic events
Special memories for traumatic events will most likely be recalled and depending on multiple factors,
the accuracy of details can be more reliable than everyday memories. But they involve similar basic
cognitive processes of construction and reconstruction. Special event memories are also malleable,
prone to distortion and affected by the processes of forgetting.
Misinformation effects and false memories
Suggestive forces such as misleading questions, inviting speculation and imagination can lead to false
details of experienced events. Various real-life studies have shown that people claim to remember
non-existent films of highly publicized events. 55% falsely reported to have seen a film about an
airplane crash and they added a detail (fire started). Their false memories were schema-consistent, as
common sense would suggest that an airplane crash involves fire. Entire false memories about
perpetrating a crime can also be developed. After strong suggestive interview procedures (imagination
exercises) and social pressure to recall, the majority of participants developed a false memory for
committing the criminal act suggested. Altogether, 25% developed false memories for entire personal
events and suggestive techniques increased this number to 46%.
,People can develop entire false autographical memories of events such as being lost in a mall, being
attacked by an animal etc. The false events recalled by children include having been hospitalized for an
injury, riding a hot-air balloon and being accused of cheating.
Under strong suggestive conditions, people can develop false memories of events in which they now
believe they are victims and perpetrations. These memories can be detailed, have a great deal of
emotion and can be confidently held, which psychologists refer to rich false memories. These
memories only occur under specific highly suggestive conditions where interviewers use cognitive and
social persuasion tactics.
Distorting a memory remains easier than planting a new memory. Discriminating between true and
false memories is a difficult task.
Factors in memory distortion and false memories
Research has identified factors that can lead to distorted memories:
Post-event information: information encountered after an event can influence memories.
External information can integrate into a witness’s memory, especially if the event was poorly
encoded. It will be integrated as a part of the original experience, especially when the new
information makes sense to him. This process can be explicit (knowing that it’s happening) or
unconscious (most often). Overtime, the witness may not know the source of the information
that led to the (new) memory. Sources of misinformation:
- Co-witness influence: when witnesses hear each other’s testimony or discuss them, it
sometimes results in a positive effect by strengthening the memory. It can also
contaminate the memories, especially when the original memory is weak. Memory
conformity is when memories of witnesses become similar over time. People who know
each other are more likely to report information from their co-witness as if it was their
own. Social media also plays a role and is a breeding ground for significant
misinformation.
- Questioning witnesses: the method of questioning a witness affects the accuracy and
completeness of reports and subsequent memory for the events. One word change has
a big influence on the witness’ reports. For instance, when they used the word
‘smashed’ they reported having seen glass, because it’s schema-consistent. The schema-
consistent effects which can be induced by the framing of the questions can influence
witnesses’ reports. Repetition of the question can cause the witness to keep trying to
remember until they produce the ‘correct memory’. The forced confabulation effect
(forcing someone to remember details they maybe do not even remember) has shown
that people can develop false memories of details in response to the repeated
questions. There is danger in repeating the same question, especially about details they
explicitly said they do not remember.
- Visuals: photographs can trigger memories but can also have a negative effect on
memory. Research has shown that photographs, combined with other suggestive
techniques, can contribute to the creation of false memories of entire events. 65% of
participants in the photo group developed a false memory, whereas only 27% of the no-
photo group did. Another example was when the police had an artist draw the scene
with details the witnesses could not remember. The witnesses had to testify at trial and
were sure of having seen details in the demonstratives, even though they reported they
had no memories of it before.
, Retention interval: the longer the interval between an event and the time witnesses have to
provide an account, the more likely the account will have significant distortions. This is because
of the natural process of forgetting. The retention interval is important, but also the recollection
context (whether the event was experienced once or repeatedly, whether the event was
experiences in childhood or adulthood etc.). It is easy to plant or misinform on false memories
for distant events because they are less vivid, less detailed and less accessible.
Imagination/visualization: imagination inflation is that the person’s confidence that the
imagined event occurred will be amplified by simple imagining the event itself, which can lead
to false beliefs. Repeatedly visualising, thinking and speculating about an event can lead to
detailed imagery that enhances false beliefs. Imagination is one of the most important factors
in memory distortion, including memories for traumatic events.
Event plausibility: this construct relates to the type of prior knowledge the witness has about
suggested events. Having general knowledge about how an event occurs, and possessing
schema-relevant information in memory, makes it more plausible to implant information about
the occurrence of such an event. What is plausible to particular individuals depends on their
knowledge base. Manipulations that suggest to witnesses that an event occurred will increase
the false beliefs that it occurred. Imagination increases the likelihood of developing a false
memory that is believed to be plausible.
Inconsistency within and across interviews: the accuracy or reliability of a detail depends on:
- The nature of the inconsistency (contradiction, addition or deletion)
- The type of detail (core vs peripheral)
- How the detail was elicited (same vs different interview or question type).
Inconsistencies can be categorized as:
- Direct contradictions: conflicting responses, different details at time 1 vs time 2. This is
the least accurate or reliable because memory of the detail tends to be poor. These are
also less likely to occur for central details of an event.
- Reminisce: more recall, new detail at time 2 but not reported at time 1
- Omissions: forgetting, detail reported at time 1 but not at time 2.
Cognitive processes in memory errors and false memories
Source memory errors: when people search for events in memory, a memory trace starts. The
source memory judgment is how people decide whether a memory representation is of an
experienced event or the product of thinking. Errors in this judgment occur when people
become confused about the source of the information. Confusion is more likely to occur when
the memory representation of a false/imagined event has the characteristics of true memories
(vivid, detailed). This error in source memory judgment is one of the important cognitive
mechanisms that explain why distorted and false memories occur and why people believed
them to be real. Visualizing objects or events in detail can be encouraged by the content of the
question.
Gist and verbatim memory traces: the fuzzy-trace theory suggests that there are two memory
traces: the verbatim (detailed actual memory of seeing a person yell) and the gist (general
interpretation of what happened). The gist memory is the basic story the witness tells himself
(he hates me). Gist contains less detail than the verbatim experience. Verbatim memory traces
fade much more quickly. This makes a memory primarily a gist memory, with less sensory
details. When verbatim memory traces are weak and gist strong, witnesses can develop false
memories which can be exacerbated by the retention interval.
, Individual differences: individual difference factors such as age, intelligence, personality
(suggestible) and psychopathology make people more vulnerable for false memories than
others. Especially people with low IQ and poor perceptual abilities are likely to be highly
susceptible to misinformation. Recovering a trauma memory through suggestive techniques are
more prone to false memories than those who report spontaneously recovering memories.
Protocols to promote quality memory reports
Relevant aspects of the two most important protocols to create quality reports from witnesses are: the
Cognitive Interview (CI) and the National Institute of Child Health and Human Development protocol
(NICHD). These are created to reduce the likelihood of misinformation effects and false memories.
They are both information-gathering protocols, where witnesses’ memory abilities and limitations and
their thoughts and emotions are taken into account.
The CI is for all groups, the NICHD especially for children. They put a strong emphasis on developing
rapport and taking a witness-centered approach (focus on the importance of question types that
promote accuracy and allow for flexibility in the use of memory retrieval techniques).
Rapport and transfer of control: to break down psychological barriers, rapport development
and maintenance is necessary when interviewing witnesses. It can start by simply letting the
witness know that the investigator wants to know him better and that they should talk about
their day. It involves interest in the person, active listening, respect and empathy. The witness
should not just answer questions, but have an active role in reporting because it’s the firsthand
knowledge of the event.
Question type and memory retrieval technique: when rapport is established, the witness
should place himself in the time frame of the target event or mentally recreate the context in
which the event took place. The professional then uses open-ended questions that prompt a
narrative response from the witness. The professional used follow-up questions that elicit more
responses about specific aspects. Forced-choice, leading and suggestive questions are avoided
because it could lead to misinformation. The professional could ask the witness to engage in
memory retrieval techniques to elicit more details (self-relevant cues, drwing and providing the
event in reverse chronological order).
These protocols are effective in improving the quantity of information elicited from witnesses without
compromising quality. Engaging in multiple memory retrieval technqiues can reduce the detrimental
effects on memory from the factors outlined previously. CI has an inoculation effect in that it may
protect participants from being influenced by misleading information. Encouraging the use of various
retrieval strategies without social pressure increases the likelihood of locating new information and
decreases the chance of misinformation
The Self-Administered Interview (SAI) uses the core principles of CI. It’s a booklet which prompts
witnesses to recall their experience immediately after the critical event. They recalled more without
compromising accuracy compared to a group who were simply asked to recall without special
prompting. It’s not always appropriate unfortunately, then the CI and NICHD are more useful. The CI
and NICHD take up a lot of training for professionals, that’s why SAI was developed.
Protocols to discriminate between true and false memories
Once a memory has been developed in a rich false memory, it’s difficult to identify it as false. Two
commonly used assessment techniques o systematically assess truthfulness in witnesses’ accounts of
events are Criteria-based Content Analysis (CBCA) and the Reality Monitoring Framework (RM). The
