October 26, 2023 | Barb Carr

Why is Eyewitness Testimony so Unreliable?

eyewitness testimony

If you do incident investigation interviews, you have probably noticed how multiple workers can witness the same incident, but their stories will be entirely different. Why is eyewitness testimony so unreliable? Is everybody lying?

Many factors make eyewitness testimony seem very “suspect.” A big one is a memory, and how memory works. Daniel Schacter wrote a book titled,  “The Seven Sins of Memory: How the Mind Forgets and Remembers,” (Houghton Mifflin, 2001) that explains it well.

Let’s take a look at the seven sins he wrote about, and see how the sins influence memory.

How Do Eyewitnesses Forget so Easily?

Schacter wrote that there are three “sins of omission” or ways we forget. They are:

  • Transcience. This describes the deterioration of memory that happens over time. The longer the pause between the incident and the interview, the more the memory may deteriorate. This is especially true after a longer (a year or more) lapse of time.
    • Try to schedule your eyewitness interviews as soon as possible after an incident.
  • Absentmindedness. This memory problem typically happens because our brains try to store information about an event, but we are distracted and thinking about something else. The brain doesn’t multi-task well. (This is also why we can’t find our keys/the dog leash/our car in the grocery store parking lot).
    • Remember that a witness may be there when an incident happens, but may have been absorbed in their problems of the day, and did not properly encode the information to memory.
  • Blocking. Have you ever been talking to someone about a great restaurant you visited on your vacation and then tried to recall the name . . . which was on the tip of your tongue but you simply could not recall it? This is blocking.
    • If your witness has a “tip of the tongue” moment, try taking a short break or tell them you will call later to see if they remember. “Tip of the tongue” information will commonly pop into your mind hours or even days after the conversation is over.

Why Does Eyewitness Testimony Sound So Fictitious Sometimes?

Sometimes an interviewee’s story can sound really “out there” and wild! Schacter highlighted four “sins of commission” or distorted recollections that can explain stories like this. They are:

  • Suggestibility. When witnesses get together and re-live an incident, suggestibility happens. You must be very careful to avoid suggesting anything to the witness because it could create false memories and even false confessions. (Yes, suggestibility can convince your brain to confess to sins you didn’t even commit!)
    • Don’t do group interviews with eyewitnesses. They will confuse each other with conflicting information, and change their stories to adapt to new information other witnesses bring. Always interview eyewitnesses one-to-one.
  • Bias. Ah, biases. We all have them, it is just part of the wonderful human experience. Humans have emotions, and emotions affect memory recall. (I also wrote about specific biases last week, Tame your Cognitive Distortions.)
    • During an investigative interview, it is sometimes helpful to find out what the witness was feeling emotionally at the time of the incident. They may have arrived to work after an argument with a loved one or may have been struggling with depression after a loss that day. If you can help them recall the feeling, the memory of the incident might be stored with it.
  • Persistence. Sometimes we experience something that we’d rather forget. Maybe a situation embarrassed us or was just too traumatizing to keep thinking about. Persistence can lead to terror and phobias.
    • If your witness saw a fatality or serious injury occur, they may not be able to recall the details. An ethical interviewer would stop the interview when they notice the witness becoming fearful or emotionally distraught. Depending on the circumstance, the witness may be able to provide information at a later time, or it may be best to collect information about the incident another way.
  • Misattribution. This memory problem will make you very suspicious of your witness! They may falsely recall something you know didn’t happen (because you already watched the security video). Or, they may think their mind is making up an event that really did happen but they are confusing it with another event – they won’t trust their own memory. Misattribution is connecting information to the wrong event.
    • Just because the story a witness is telling you seems wild and way off track doesn’t mean they don’t believe it’s true.

So, now you know that when a witness gives you false information, he or she may believe they are telling the truth. The science of memory proves it!

What do you think is the biggest memory problem you deal with as an incident investigator of the seven listed above? Leave your comments below.

To learn more about the science of a good investigative interview, please consider registering for my 2-Day PreSummit Course. It will be held April 29 – 30, 2024 at Horseshoe Bay Resort near Austin, Texas.

I love this course, and we have a lot of fun not only talking about improving incident investigation interviews but also practicing new skills in mock interviews. Stay a few extra days at the resort and join us for our 3-Day Global TapRooT® Summit, May 1 – 3.

Interviewing & Evidence Collection
Show Comments

2 Replies to “Why is Eyewitness Testimony so Unreliable?”

  • Reynaldo Sabandal says:

    Most of the time the witness is not telling the truth because of fear of being blamed by others or the witness is protecting their co-workers.

    • Barb Carr says:

      Very true! There are ways to minimize fear in a witness (including building rapport) which are built into the TapRooT® 12-Step Interviewing Process.

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