Eyewitness Testimony’s Large Margin of Error
Testimony provided by credible eyewitnesses plays a major role in the criminal justice system. These accounts are commonly used to paint a complete and accurate picture of the crime, and they have been known to make or break the case of a client of a Pennsylvania criminal defense attorney.
When an eyewitness is shown not only to be a trustworthy person but also someone whose memory and perception can reasonably be counted on, the testimony they provide in court may be used as evidence that holds unduly significant weight. If an ideal witness has sufficient confidence in what they saw, it may be enough to sway a jury that has no reason to doubt the validity of their statements.
But when eyewitness mistakes are made, the stakes are often high. These errors may end in tragedy for the falsely accused, who ultimately have to pay the price for what is a common psychological phenomenon.
The Psychology of Eyewitness Memory
There’s a difference between witnesses who give inaccurate testimonies versus general forgetfulness. The psychology behind flawed eyewitness testimony is significantly more intricate than your average memory issues, and this is owed to the variety of factors involved.
The idea that no one’s memory is flawless has been around for decades. Psychologists have long been aware that people’s recollections quickly become altered and shortened while many of the key details steadily slip further away the more time ticks by. To muddy the waters even more, the human mind likes to reshape these memories so that they fit better into what the individual personally already believes.
Elizabeth Loftus conducted some of the most well-known experiments that revealed the influence of post-event information on memory. As it applies to eyewitness cognition, post-event information refers to input that a witness receives during the time between when they saw the event and when they provide their testimony.
In the famous Loftus and Palmer experiments of 1974, respondents were shown a video of one car rear-ending another at a low speed. The way these respondents remembered the video changed based on the language that was used to describe the collision afterward.
The Difference That One Word Can Make
The wording seemed to influence how fast they perceived the cars to be moving as well as the intensity of the collision. Although only one word was changed, it made a difference in the way respondents remembered important details. This showed how easy it is to overlook this post-event information and how it may be included unintentionally.
When the word “hit” was used, respondents were able to estimate the speed of the vehicles fairly accurately. But when changed to the word “smashed,” more respondents felt they were able to confirm that damage was done to one or both of the vehicles. Respondents thought they saw glass breaking, although that hadn’t happened at all in the film they saw.
Loftus performed another study in 1979 involving a short video, but this one did not include a collision. This time, interviewers slipped in an added piece of false information. Many respondents accepted the suggestion because they were focused on the details in question rather than the assumed fact that was presented to them.
Participants were asked how fast a vehicle was traveling as it went past a barn down a rural roadway. A high percentage of the respondents said they could remember the barn, but there wasn’t one. The experiment showed how the information that people receive after the fact can cause new details to manifest.
The Information That Is Already Present
In addition to what enters the mind of a witness after they see a crime occur, extraneous information also plays a role. This refers to what they already have in their mental bank: things they remember from the past that inform their perception of the present. It also plays into how people reconstruct memories.
Some studies have shown that what a witness already knows about types of guns and other weapons has a direct influence on how accurately they will identify a weapon used in a crime. This is true whether they know about firearms from:
- Movies
- TV shows
- Video games
- Military
This comes into play with common firearms like a Colt .45 semiautomatic pistol versus something like a short-barreled revolver. A witness may be less familiar with the latter, but this type of weapon is much more commonly used in real-life crimes.
As an investigation is conducted, details such as the weapon that was used can repeatedly transform, although the witness is no less certain about their testimony. It’s not that they’re trying to be deceptive; when these mistakes happen, it’s because the witness truly believes what their memory tells them.
The criminal justice system has seen a real impact as a result of these eyewitness mistakes. This is not the fault of the witnesses, who are simply doing their best to remember. These witnesses genuinely believe that their memory has it right, and they’re playing their part in a system that still gives undue weight to these accounts.
The types of falsely identified weapons that perpetrators are often remembered as wielding tend to be expensive firearms of the type that police officers typically use. But for perpetrators who are trying to rob a store because they’re desperate for cash, this doesn’t add up.
A Stressful Environment
It’s not always obvious which preconceived notions or post-event information will lead witnesses’ memories astray. To further add to the confusion, a stress-free environment is a luxury that eyewitnesses are rarely afforded.
The aftermath of a crime is often hectic, and things move fast. It’s enough to cause a state of distress in anyone, even if you weren’t directly involved in the incident. Adrenaline may be pumping, and this heightened emotional state prevents the mind from functioning at its best.
But an initial report, by its very nature, has to happen right away in an attempt to capture details and impressions when they are fresh. Law enforcement has to operate quickly in the immediate aftermath of the crime and can’t afford to wait until everything is calm and quiet.
These conditions are unfortunately ideal for post-event information to latch onto a person’s memory. People are more willing to accept suggestions of added details that they didn’t witness for themselves. This is especially true since they’re talking to officers of the law, who they may presume have better or more complete information than they do.
A Common Officer Mistake
A witness who has no prior experience with firearms may be initially unable to identify the weapon type. They might not be able to tell whether there was a gun involved at all.
Some police officers have made the mistake of presenting a witness with their own service weapon in an attempt to help their memory. Their intention is often to provide something for reference so they can better identify the weapon through comparison.
However, this tends to only pollute the person’s memory. While the witness had only a vague sense of the weapon used by the perpetrator, the gun that the officer showed them was clear and detailed.
They have time to look it over, so they can develop a strong mental image with clear features. This tends to supersede whatever weapon they had already remembered, no matter how accurately this piece of post-event information fits into the true story.
Not all law officers are aware of these psychological factors or how they play into their interactions with witnesses. The subtlest suggestion can contribute to eyewitness errors and skew everything from minor but crucial details to the big picture of the whole story.
The law firm of Bauer, Scanlon & Wigginton understands the pitfalls of eyewitness testimony and how to navigate them. Call 610-590-5092 to set up an appointment with one of our Media, Pennsylvania criminal defense attorneys to discuss your case.