Home > Aging, Memory > Innocent Criminal: The Science behind Inaccurate Eye-witness Testimony.

Innocent Criminal: The Science behind Inaccurate Eye-witness Testimony.

Innocent Criminal: The Science behind Inaccurate Eye-witness Testimony

Ever noticed CSI shows? Every time a crime is committed, the potential perpetrator is told to stand behind a glass frame. Along with him or her are more people. What’s intriguing about all of this is that every single “false criminal” looks very similar to the original criminal. Whether it be the tattoos, the similar age, or maybe even the clothing, there is a sense of similarity across the spectrum. That similarity is done for a reason. Suspects who have distinctive features like a birthmark or scar were the easiest to identify in a line-up. To prevent any bias, all those in the lineup have similar features and physical stature to the perpetrator. While in theory this seems legitimate, in reality there are flaws. Previous research has shown that older adults show a decline in visual discrimination over time. Recollection of facts and events gets more difficult as people age, so older adults struggle to connect faces to distinctive features. This supports the idea that older adults with associative deficit hypothesis have a harder time identifying distinct features of a face when they are presented with other faces that look familiar.

Research has shown that eyewitness testimony is not a very accurate way to identify suspects who may have committed a crime; yet, eyewitness testimony is one of the most critical pieces of evidence that investigators use to build a case. New research is being done to figure out ways that law enforcement can help individuals who may have witnessed a crime, properly identify the perpetrator. Distinctive features such as moles or tattoos are things that help differentiate people. Witnesses rely heavily on these distinctive features when they are asked to identify a suspect.

In their study, “Replicating distinctive facial features in lineups: identification performance in young versus older adults,” Badham, Wade, Watts, Woods, and Maylor examine the accuracy of eyewitness testimony in younger and older adults. Sixty young adults and ninety older adults volunteered to participate in their study. They had four different experiment conditions. For their manipulations they used computer technology to digitally remove or replicate any distinct features (moustache, mole, tattoo, birthmark).

They were given the option of answering none if they did not think the target was present. In two of the conditions, the stimuli contained the target face, and in the other two conditions the target was absent. (Imagine being given a multiple-choice questionnaire and the answer not being presented, and you do not have the option of answering none of the above. hat is what the target absent would be like if you couldn’t answer ‘none of the above!) The participants were presented with a picture of a target and asked to identify that target in mix of six stimuli. In half of the experiments, the distinctive feature (bruise, mole, moustache, piercing, scar and tattoo) was applied to all of the stimuli and in the other half the distinctive feature was removed from the stimuli. The participants assumed that the target would be present in all the line-up since they were being asked to identify who they thought was the target in the mix of faces.

criminals

Fig. 1 Examples of distinctive features (top) digitally added to faces (bottom). From left to right: bruise, mole, mustache, piercing, scar, tattoo.

In the target present condition, where the distinctive feature was applied to all the stimuli, younger adults were more accurate at identifying the target then the older adults. Older adults were also more likely to identify a non-target in the target present condition then were the younger adults. When the distinctive feature was removed from the stimuli, the older adults had a more difficult time identifying the target then were the younger adults. In the target absent condition, younger adults were more likely to identify when the target was not present in the line-up then were the older adults. Younger adults were more likely to respond none in the target absent condition when the distinctive feature was either added to or removed from the stimuli.

The results indicated that younger participants were more accurate at identifying a target then were the older participants. Age also had an effect when it came to the replication and the removal task.  For the replication task, younger adults were more accurate at identifying a target then were the older adults. This indicates that younger adults were able to differentiate between the non-targets and the targets with more ease than the older adults and for the majority of the time they were accurate. Older adults performed about the same on both the replication and the removal task. An explanation for why older adults perform worse on removal tasks can be because they rely more heavily on familiarity. This makes it more difficult for them differentiate between stimuli that may look similar.

So if there are all these flaws in eyewitness testimony, why is it still being used in convicting suspects? Research has shown that it is very easy for memory to be distorted, especially in older adults. Since this form of evidence is still critical in convicting suspects, law enforcement needs to make changes so that older adults make the least amount of mistakes when they identify perpetrators. The possibility that an innocent person could be sent to prison for a crime that they did not commit is frightening. Improvements need to be made so that there are many forms of evidence needed to convict someone.  They also need to make it clear that there is a possibility that when they get people in a line-up that the target described might not be in the line-up. As citizens, we depend strongly on our security systems, and we need to make sure that the individuals who end up paying for the crime, are actually the ones who committed the crime.

 

Reference

Badham, Stephen, Wade, Kimberley, Watts, Hannah, Woods, Natalie, & Maylor, Elizabeth.  (2013). Replicating distinctive facial features in lineups: identification performance in young versus older adults. Psychonomic Bulletin and Review, 20 (289), 289-295.

Doi: 10. 3758/s13423-012-0339-2

 

 

Categories: Aging, Memory Tags: ,
  1. May 6th, 2013 at 22:59 | #1

    This is an interesting conclusion. I have a few questions regarding some more possible factors. Do eyesight and/or brain development played roles in identifying the target as well? Is there any part of the study that talked about how older people may also simply have worse eyesight on average an thus identifying a target might be a more difficult? Also do you think there could be an age bias?

  2. May 8th, 2013 at 20:34 | #2

    spittballing of the last part of the question above about bias. Would there be different results or more errors for individuals of different races due to the races faces bias? If so, is it even practical to do a line up with people of different ethnicity?

  3. May 11th, 2013 at 14:07 | #3

    This was really interesting and also slightly unsettling to read about. I wonder if there is as well an age bias in the sense that younger people are better at identifying younger people, and older people are better at identifying older people.

  4. May 12th, 2013 at 15:12 | #4

    This article makes me wonder how much flashbulb memories play a role in eyewitness identification of perpetrators. Could a flashbulb memory somehow alter the memory of the appearance of the perpetrator? Any event in which an eyewitness is necessary seems indicative of a flashbulb memory, which would be very difficult to produce in a lab setting.

  5. May 15th, 2013 at 15:42 | #5

    I think that bringing up the setting is an interesting point. Often in criminal situations an eyewitness observes many different variables that can influence recognition, which can include how the perpetrator walks, how they speak, what they smell like, etc. and all these combined together can help effectively differentiate between people. I wonder why line-ups occur at a police station versus having the potential perpetrator and similar-looking innocents re-enact the scene. With everything we know about how environment can influence memory, it is surprising that line-ups don’t occur in the same scene as the crime. I also wonder at what age do we begin to lose our ability to recognize faces? Is it gradual, or at some point in our life does this ability drop off suddenly?

  6. May 18th, 2013 at 16:09 | #6

    This is an interesting study with interesting results. I wonder how the ability to differentiate between faces changes over time. I would be curious how other age groups would do in this test in comparison. Does this mean that an elderly person’s eye-witness testimony should warrant less standing in a court case? At what point does eye-witness testimony become a risk to innocent civilians being wrongly convicted?

  7. May 18th, 2013 at 21:28 | #7

    The topic of this article is very interesting, as it is such a controversial subject. As you stated, TV shows make eye-witness testimony seem like it never fails and is always accurate, when that is clearly far from the truth. One of the most intriguing aspects of this study, in my opinion, is the idea that our ability to differentiate between faces and their characteristics actually deteriorates over time. If that is the case, is there a measurable rate at which this ability decays? Obviously it would be hard to measure but it would be interesting to see more data on this. This post does a great job illustrating the flaws of using eye-witness testimony to convict guilty (or maybe their innocent) individuals. Personally, I believe eye-witness testimony should never be the sole evidence used to convict someone, as the inaccuracies are clearly well known today.

  8. May 19th, 2013 at 22:07 | #8

    This post really made me think of ‘My Cousin Vinny,’ specifically the scene where eyewittness testimony is thrown out because of the eye sight of the wittness. The more and more I read about eyewittness testimony the less faith I have in it. But is there a way to phase out, or at least rely minimally on eye wittness testimony? I believe this is an issue that we have to tackle, the science is too strong.

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