Expert explains why eyewitness testimonies can be unreliable in solving crimes

After showing the results of the "GMA" social experiment, former Secret Service agent Evy Poumpouras discusses why our memory of a crime may fail us.
7:53 | 11/10/17

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Transcript for Expert explains why eyewitness testimonies can be unreliable in solving crimes
Work here man. Did it Delaware where ticket given that. I can't help you do I just came from California I need some help here to do the death and death dear I said I can't help. Hey no worries everyone. In case you haven't guessed that was our social experiment we're gonna break at all down from the from not. Audience how have you witnessed the stage altercation between two actors in our studio just. As you've probably got something out there isn't just about altercation in the CI can't help we asked do you remember exactly. What happened when it comes to solving a crime. Eyewitness testimony is key but just how reliable is at work about the find out. With a look. The faces that landed behind bars for crimes they didn't commit. Some of the thousands who were wrongfully convicted of a crime based on what eyewitnesses. I thought face off. Eyewitness errors are common because most crimes are very fast. And so witnesses have a limited opportunity to be able to see the perpetrators. Roughly 13 of cases in which a person was wrongfully convicted of a crime and later cleared of all charges. Is due to what experts call mistaken eyewitness identifications. That's when a witness gets it wrong about who the per arbitrator is and what happened. Can it yeah. This morning we put the accuracy of eyewitness student test cannot live social experiment that our audience witnessing a state altercation on sex. What do they remember and what actually happened. It's more than meets TIL now the results reveal live. And we are joined now by street analyst former Secret Service agent any palm course every thank you for joining us. This morning in you know you there was a guy opening right there we know the innocence project isn't worth 7%. Convictions overturned by DN Evans were based on on reliable eyewitness testimony. Why do I wouldn't think get a wrong so often. He knew you wanting a stressful event are you having the stress response your adrenaline does KK and so when you're watching me vent your hyper focus on. What's happening the action cannot paying attention to the description of the clothing or even the description of the person's face which is why so many people get it wrong. All right audience we want to see just how much you remember about the incident that took place just a short while ago as a grab your clicker is. Everybody has them we're gonna pass through a series of three multiple choice questions about what happened so good looking your best dancer. So the question we first asked. Was the perpetrate are wearing glasses. Click a B or CAA is yes B is now see is not sure. And the results. Look at that meet gut B 891%. Which is. True no classes so they got a we have reliable eyewitness who. If you notice we did have a couple of people who actually did click that yes but for free trader was wearing glasses this is something that's called transpose -- it's it's a source of confusion we'll literally take. In the accessories and clothing from one person and transpose them onto the other person and sometimes it happens with the victims. They'll actually confuse the clothing description from a perpetrators on to a person who was actually come to help them. Afterwards. Gregg because sometimes it's not just ten minutes later it's a day later or a week later and those memories to confuse or its we have our second question for the audience. What color was the perpetrators hair click in your answers a dark brown. Beam light brown C black where dean dirty blocked and we have the results in right now so. They're still there are still growing but it looks like a dark brown. Is going to win it and that is the young men is true it's an interesting that we have some people out how hot it's. Yeah how many they believe did have some people actually picked the last choice which was light blond. Excuse me doc wants. And it would not situation is when people don't know what to take big deep faulted to their last choice. Also hair term of gas will we don't know what a pic it's always a last Joyce. Com and hair color subjective so for example I have very light hair color so when I see somebody with brown hair I may interpret that as dark brown or even black. Would you have darker hair George so yes I did. You think you might look at Kelly's hair color differently when you look at it. All right we've got our third question. What was the age of the perpetrators. A 29 B 36. C 42. Or. And it looks like most people think he was a 29. But I believe the real answer is full flat who actually not gonna say they're real and hiring yet because of me wanna. Show something else afterward but let's talk about H brown moment so when somebody is closer to lessen age we are more accurate ad describing that person's age. When we are farther apart from that person in age we are less accurate. You could argue this to me like a gift of the morning both in 2936. At all it's the same happened. We'll we also please labs also key component in identifying a suspect in we have one. Of Iran's who want to bring him out right now. Kevin take a good luck. And then we want you know if you. Can identify the person who is involved in the incident click. Eight BCD. Or me for none of the about. Cool. I have most people are going with. I'm your guy. Yes but we do have some people who picked other choices so this is what happened in the situation with with police lineups. Sometimes a person feels compelled that they feel like they have to choose somebody in the lineup. And because of that the end of choosing someone that sometimes is not even neck. It's an accident take away from this experiment the big takeaways if you are someone you see something to be a good witness remember what we just had disgusted day. Try to remember what you are seeing an all those descriptions will really help law enforcement and also don't feel compelled to give an answer if you don't really know right yes yes he can say I don't know and that's in that's honest sometimes the brain actually plugs and information for us. And we think we're not sure if it's truth efforts also just if you don't know to say I'm not I wonder what. Different sort of maybe because there's an audience to do quite well here with the fact that we also showed he had some again in a little bit in my. And there's a fairly short period of time it was yes 'cause you have to also think about how long it takes police to get to an event after the fact and you sometimes are talking. But it's we did this ten minutes but usually is meeting our a couple of hours before the interview semblance of the audience most of the audience believe that the fervor trader was 29 but the actual age was quite different. Actually age was 42 of the country and I big like how they gonna differences that make when police are looking for someone. He candy because they're looking at somebody who's in their forties vs somebody who's an early twenty's. Absolutely. Things an official working here since seemed like some of those witnesses were influence that what they were seeing go up. On the board and things are shifting around a little bit they're can be influenced by other people story. Yes you can meet you can also be influenced by other people that's when you interview people you want to isolate people you don't want people listening to the answers of somebody else. Also it's a way that police can Haskell question. To someone that you can influence someone's answer as well but it's like nearly interest. Yes thank you so much Devi and debts also to turning technologies for providing us with our survey software. And be sure to subscribe to ABC news podcast murder on orchard street new episodes drop on Tuesday into you can also watch the entire series. On our website abcnews.com. Slash orchard street.

This transcript has been automatically generated and may not be 100% accurate.

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