The power of the mind influences the way that we perceive reality and therefore remember it.
May 2011
by Robert A. Goerman
Eyewitness testimony is a common form of evidence in law and the legal system has mechanisms to test witness evidence for reliability or credibility. Examples of approaches to testing and assessment include the use of questioning, evidence of corroborating witnesses, documents, photographs or video and forensic evidence.
This testimonial evidence is sometimes also described as anecdotal evidence.
In science, anecdotal evidence is defined as casual and non-scientific observations which do not provide proof but may assist research efforts.
The formal study of eyewitness memory is usually undertaken within the broader category of cognitive processes. Cognitive processes refer to all the different ways in which we make sense of the world around us. We do this by employing the mental skills at our disposal such as thinking, perception, memory, awareness, reasoning and judgment. If you accept that the way we think, perceive, reason and judge is not always perfect, then it’s easy to understand why psychologists study cognitive processes and the factors influencing these processes.
Is seeing is always believing?
Our normal perceptions do not correspond directly to reality. The things that we perceive are not entirely determined by what our senses detect. Our perceptions are also determined by what we expect, what we know, and what we believe. This constructive perception helps us make sense of the world. Perception is a selective act, dependent upon belief context, expectation, emotional and biochemical states, and a host of other variables. Memory is prone to a range of distortions, deletions, substitutions and amplifications. Therefore the testimony that people offer of what they remember seeing or hearing should always be regarded as only approximately accurate.
Testimony should never be regarded as reliable evidence in and of itself for the simple reason that any human being can lie or make a mistake. Sincerity lends nothing to the credibility of testimony. Even if people are telling you what they sincerely believe to be the truth, it is always possible that they could be mistaken or mentally impaired. For example, some people confess to crimes they have never committed.
Psychologists inform us that the memory process can be divided into three stages. The first is the acquisition or entry of the information into the memory system. This is followed by the retention stage, during which time elapses before the witness tries to remember the event. The retrieval stage occurs when the witness recalls the stored information. Events at any of these stages can be the cause of memory failure. The information simply may not have been perceived in the first place because the witness was not looking, the lighting was bad, the event did not seem important or many events took place in a very short time.
Acquisition
Certain aspects of human nature come into play when a person witnesses, or is part of, a dramatic event. The witness rarely observes all of an occurrence, and even if they do, the tendency is to report those events which were most vivid. Because of selective attention, different people see different things.
Both event factors and witness factors influence the acquisition stage or the perception of the event.
Event factors include environmental conditions such as weather, visibility, time of day and ambient light, as well as the duration of the event and distances involved.
Witness factors include fear and trauma (more stress equates to less clear memory) and personal significance (more personal involvement equates to better memory).
Alternatively, the event initially may have been perceived incorrectly because the witness interpreted the event consistently with his or her expectations and stereotypes. Often we fill in our observations of reality with the way we think things should be, based on our expectations. And when these misperceptions become part of our memory, they can affect new perceptions and interpretations. Did the witness recognize and understand what they were seeing?
Questions regarding the state of health of the witness need to be asked: Do they wear glasses? Were they wearing them at the time? Were they under the influence of alcohol and if so, how much had they imbibed? Were they under the influence of medication or “recreational” drugs? Had they had emotional problems or suffered from hallucinations, dizzy spells or memory loss? Have they seen this phenomenon before? If so, where and when?
Retention
Memory does not function like a video recorder which captures an event and stores it for future playback. Images recorded electronically do not change over time and are not altered by external or subsequent events. Memory, on the other hand, changes and fluctuates based upon several factors. When someone experiences an important event, that person acquires fragments of information from the environment. This information then is combined with information previously stored in memory, with information acquired after the event occurs, and evens with prior expectations. The result of this amalgamation is the current memory of the event.
The length of the retention interval, meaning the time between when the memory is acquired and when it is retrieved influences the retention or storage stage. There is a natural fading of memory and all witnesses forget some information as time passes. The longer an event is in the past, the more likely the witness will have only a partial memory of it. Even some of the simplest and most obvious facts may have been forgotten.
Numerous studies have shown that eyewitnesses incorporate information learned after the event into memory. “Post-event contamination” or “post-event information” is information that is learned after an event takes place that is then integrated into the memory of the event. After integration occurs, it generally is not possible to disentangle information which came from the event itself from information which was learned and became integrated later on. To the degree that the post-event information is false, this results in the ultimate memory becoming more inaccurate. Examples of post-event information include leading questions, overhearing other witnesses talking about the event or engaging in conversation with other witnesses, reading about the event in the newspapers or viewing an account of it on television, and other similar occurrences.
Human memory does not exist so that an observer may accurately report previously seen events. Each witness extracts an interpretation that is meaningful in terms of his own beliefs, experiences and needs. Once the interpretation occurs, the events themselves become relatively unimportant. Moreover, since each person interprets the events in terms of his own worldview, different eyewitnesses observing the same event may have different interpretations and different memories.
Retrieval
The way in which information is retrieved from memory also appears to affect recall. Even information perceived and retained accurately can become distorted by improper questioning. The retrieval stage is affected by whether a witness is asked specific questions or is asked only to give a narrative description. Narrative reports are more accurate but less complete; answers to interrogatories cover more of the events but contain many errors. Witnesses, when questioned in detail, become aware of gaps in their observations and may apply logic, answer in generalities, and add to their statements to make their observations seem more plausible.
Assessing witness reliability
It is advisable for the investigator to have some knowledge of following factors to better understand why witnesses report as they do, as well as to ascertain the reliability and validity of the information:
Intelligence is not as much a factor in observing phenomena as it is in the area of ability to recall and in the organization of thoughts. The less intelligent witness may have difficulty presenting their observations in an articulate and coherent manner.
Emotions tend to produce distortion and exaggeration, especially in the verbal description of an occurrence. The degree of accuracy depends partly on the observer’s mental state at the time and partly on the complexity of the situation.
Repetition may cause witnesses who have spoken to many people about their experience to exaggerate or “fill in gaps” with each retelling. As people recall an event over and over, they drop details from earlier versions and add new ones. The more times an eyewitness is questioned, all things being equal, the less accurate the latest version will be.
Transposition can occur when witnesses report all facts accurately, but place them out of sequence with the actual occurrence. Make every attempt to verify the chain of events independently.
Omissions of details are common in witness statements. This most frequently occurs because the witness does not consider certain information significant.
Preconception can influence what a witness remembers. If they hear an explosion, they expect to see fire and will remember seeing it. Believe it or not, children have more open minds and are often more reliable than adults.
Robert A. Goerman is a native of New Kensington, Pennsylvania. As an author and investigative scholar of the unknown and unexplained, he has been fortunate enough to have his research and writings featured in national magazines and serve as source material for many books and television shows such as Unsolved Mysteries, The Unexplained, History’s Mysteries, Animal X, and MonsterQuest.
