Eyewitness Memory: Wrongfully Convicted


I felt compelled to write about eyewitness memory by a recent blog entry which I feel paints a misleading picture of the nature of memory and the (un)reliability of eyewitness memory.

Other skeptics have written about the subject and coverage has ranged from the pretty good to not so great. This blog post is somewhere in between. I have a great deal of respect for Vandy Beth Glenn and her knowledge on a wide range of topics, but I feel the need to address some issues in this piece that I think are important.

My first problem is that the inaccuracy of memory is overstated.

We don’t remember very well events that really happened to us.

Vandy Beth asks:

[S]hould eyewitness testimony be declared inadmissible evidence in court?… Eyewitness testimony has … brought many infamous individuals to account for their crimes. However, we shouldn’t doubt that at least as many innocents and patsies have been wrongly made to pay as well… We shouldn’t accept a faulty system just because it works more than 50 percent of the time.

How does one get the impression that eyewitness memory is so bad and so hopelessly unreliable that a reasonable solution is to toss it out all together? The literature on the subject of eyewitness memory (let alone memory generally) is vast and complex. Watching a presentation on false memory by Loftus and visiting the Innocence Project website, does not give one the requisite knowledge to make informed policy recommendations. Though I’m sure this is not the extent of Glenn’s knowledge on the subject, these are the only sources cited.

Daniel Loxton has argued that when skeptics write about things outside of their domain of expertise, they must exercise due diligence.

Skeptics solicit … trust. We make the implicit (and sometimes explicit) promise that we are able to provide the nuanced, objective, evidence-based facts. That combination of stated commitment to science, limited qualifications, and weighty ethical responsibilities … place a very high due diligence burden upon skeptics.

When Ed Clint, co-founder of the Skeptic Ink Blog network, and blogger at Incredulous, posted this article, I voiced concern regarding the exaggerated negative portrayal of memory, however both he and Vandy Beth seemed to believe this view was justified.

Ed, essentially began a lengthy explanation about eyewitness memory errors, not quite addressing my criticism and then side-stepping it altogether, saying that it doesn’t matter how many have been wrongfully convicted …

We can’t know if eyewitness testimony is the leading cause of wrongful convictions because most such convictions will never be found out, and the pattern of which get found out could be biased in one or other direction. The evidence suggests that it is, and that’s as far as we can go.

But is that really important here? If anything beats this cause, it is prosecutor misconduct, and reform is needed there, too. But prosecutor misconduct is, at least, a known problem that juries and judges are mindful of (or should be). Are they equally mindful of the problem of unreliability of eyewitnesses? Or do they assume it is correct, if the witness is firm and sure on the stand? I’d guess the latter is the case, and in the most dire need of being addressed. This is true whether eyewitness misidentification is the #1 cause or #10 cause of wrongful convictions. I, frankly, don’t give a fuck what number it is. Steve Titus should not be dead.

Vandy Beth appealed to Elizabeth Loftus’s authority and reputation.

I admit I didn’t do my own research…I relied on my sources, like Elizabeth Loftus and the Innocence Project, to be themselves reliable. If you think they’re wrong, and can back it up, I’d be glad to learn about it.

I am confident that both Ed and Vandy Beth will recognize that I mean no disrespect in the criticism that follows. I consider Ed a friend and, having just met Vandy Beth, hope to one day call her a friend as well.

Yes, Steve Titus (and the many other exonerated individuals whose stories are detailed on the Innocence Project webpage) should not have been convicted. It very rightfully violates our sense of justice that these wrongful convictions have occurred and we feel outrage. This may motivate us to want to offer solutions to the problem that would prevent miscarriages of justice like this from occurring again and give us the sense that we have a good grasp of the nature of memory. But, it is not that simple.

We cannot know the truth in each criminal case, thus preventing us from being able to estimate the true incidence of wrongful convictions as a result of eyewitness memory. However, there is no data of which I am aware that suggests that the legal system gets it wrong in half of all cases as suggested by the text quoted above. A database of 317 exonerations since 1989 tells us that errors occur and that they are not exactly uncommon. But perspective is important, lest we erroneously conclude that the justice system is as broken as we mistakenly perceive our memories to be… According to published statistics from the Department of Justice, in 2010 alone, cases were filed against 91,047 defendants. Ninety-three percent, 81,934, of defendants were convicted. And of those convictions, 97 percent, or 79,260, pled guilty.

Agreement from more than one witness is not much assurance of accuracy, either. Approximately 36% of the first 250 Innocence Project exoneration cases involved the testimony of more than one witness (Garrett, 2011). If all witnesses are subjected to the same biased lineup procedure, it’s not inconceivable that they may all choose the innocent suspect. And proposing to eliminate eyewitness testimony altogether is an absurd “toss the baby out with the bathwater” sort of solution.

It is tempting to assume that we might get rid of problematic eyewitness memory and instead rely on physical evidence, such as DNA evidence, because we perceive it to be more reliable. One problem with this approach is that in 90 to 95% of cases DNA testing is not an available option (Innocence Project, 2014). Furthermore, physical evidence is not immune to error or bias; it can be contaminated or it can be interpreted incorrectly (Murphy & Thompson, 2010; Thompson, 2006). Adherence to established standards and procedures for the collection, storage, testing, and interpretation of that evidence helps minimize the incidence of errors. Eyewitness memory can be thought of as analogous to trace evidence. It is evidence that law enforcement must collect from the mind of the witness while exercising the utmost care not to contaminate it.

Memory researchers would have long ago been done with the context of the legal system when it was first established that eyewitness memory can be inaccurate and unreliable. But the literature does not support such a negative view of memory. If our memories were so poor we would have serious problems functioning in day to day to life and it would not be possible for the layperson to live blissfully unaware of the potential frailty of memory. Elizabeth Loftus’s work on false memory shows us that false memories are possible (e.g. a quarter of participants reported a false event in the famous “Lost in a Mall” study, Loftus & Pickrell, 1995) but not that false memories are so pervasive that we should never trust our memories. “We make no claims about the percentage of people who might be able to be misled in this way, only that these cases provide existence proof for the phenomenon of false memory formation” (Loftus, Coan, & Pickrell, 1996; p.207)

Long before Loftus even began her work on the misinformation effect and later false memories, Hugo Munsterberg (1908) had noted the potential for inaccuracy in eyewitness memory. We could have written off eyewitnesses as hopeless then and moved on to other problems. Instead, Munsterberg and eyewitness researchers since have spent decades trying to identify what factors influence accuracy in an effort to offer more practical solutions to minimize inaccuracies in eyewitness testimony and identifications while also contributing to a better understanding of the nature of memory as a whole.

While confidence, detail, and vividness do not predict accuracy, eyewitness researchers have been exploring the influence of countless other variables as well. We have identified some factors related to accuracy which we cannot control (termed estimator variables, see Wells, 1978) but are nonetheless helpful to be aware of because they signal which instances of eyewitness memory are more error-prone, such as, poor lighting, short exposure to culprit, stress, witness intoxication, the presence of a weapon, mismatch between witness and culprit race, etc. Other factors which can influence accuracy and are under the control of the legal system (termed system variables) have also been explored: whether witnesses are shown books of mug shots, making composite sketches, the specific lineup instructions given, the composition of the lineup such as the number of persons included and how the fillers were selected, the format in which the lineup is presented (e.g. simultaneously or sequentially), blind administration, etc. All of these variables are at play and this is what forms the complexity that requires greater familiarity with the primary research.

Regarding eyewitness identification research specifically Wells & Loftus (2003) say “The primary lesson of the eyewitness identification work is that mistaken identification rates can be very high under certain conditions and many of these conditions could actually be avoided by the use of scientific procedures for lineups”, p.150. This research has helped to inform important guidelines and recommendations for law enforcement agencies; a committee of experts assembled by The Justice Department published a set of guidelines for law enforcement (Technical Working Group for Eyewitness Evidence, 1999). Increasingly more jurisdictions (state and local) are adopting reforms aimed at improving the accuracy and reliability of eyewitness identifications and testimony; for example, approximately 32% of law enforcement agencies have switched to a sequential lineup procedure (Police Executive Research Forum, 2013).

Memory is certainly malleable and it is reconstructive, but this does not mean that eyewitness testimony can never be trusted or be valuable in court. It can … IF certain conditions are met.


Garrett, B. (2011). Convicting the Innocent. Harvard University Press.

The Innocence Project (2014). Unreliable or Improper Forensic Science, retrieved from: http://www.innocenceproject.org/understand/Unreliable-Limited-Science.php

Loftus, E.F., Coan, J.A. & Pickrell, J.E. (1996) Manufacturing false memories using bits of reality. In L. M. Reder (Ed.) Implicit memory and metacognition. Mahwah, NJ: Lawrence Erlbaum Associates, pp. 195-220.

Loftus, E., & Pickrell, J. (1995). The Formation of False Memories Psychiatric Annals, 25 (12), 720-725 DOI: 10.3928/0048-5713-19951201-07

Munsterberg, H. (1908). On the Witness Stand.

Murphy, E., & Thompson, W. C. (2010). Understanding potential errors and fallacies in forensic DNA statistics: An amicus brief in McDaniel v. Brown Criminal Law Bulletin, 46 (4), 709-757.

Police Executive Research Forum (PERF), & United States of America. (2013). National Survey of Eyewitness Identification Procedures in Law Enforcement Agencies.

Technical Working Group for Eyewitness Evidence. (1999). Eyewitness Evidence: A guide for Law Enforcement. Washington, DC: National
Institute of Justice.

Thompson, W.C. (2006). Tarnish on the “gold standard”: Understanding recent problems in forensic DNA testing The Champion, 30 (1), 10-16

Wells, G. (1978). Applied eyewitness-testimony research: System variables and estimator variables. Journal of Personality and Social Psychology, 36 (12), 1546-1557 DOI: 10.1037//0022-3514.36.12.1546

Wells, G. L. & Loftus, E.F. (2003). Eyewitness memory for people and events. A. M. Goldstein (Ed.) Handbook of Psychology. Vol 11 Forensic Psychology (I.B. Weiner, Editor-in-Chief). New York: John Wiley & Sons, pp 149-160

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10 comments to Eyewitness Memory: Wrongfully Convicted

  • GregB

    While your overall point is well-taken, I call “BS”on a couple of things.

    First, using DOJ stats showing that 97% of convictions where do to defendants pleading guilty ignores another very large (and largely ignored, particularly by institutions like the DOJ) problem of gross over-charging by prosecutors in the US. Harsh mandatory minimum laws, and the fact that fighting criminal charges brought by the state can lead to immediate financial ruin absent any court result, very often force defendants to plead out. The lower on the socio-economic totem pole you find yourself, the more likely this is to be a proble, which is why I’d guess a person with time to blog wouldn’t appreciate this point.

    Second, while it wasn’t raised by you…does any informed adult actually think the pervasive problem of prosecutorial misconduct is actually well-appreciated? There is little evidence to suggest this. Prosecutors caught red-handed in all sorts of terrible conduct are very rarely reprimanded by name, making it impossible to hold repeated offenders to account. Lock-em-up judges often overlook egregious behavior that to a less biased eye might lead to different outcomes at trial. And as we have seen time and again from such cases of pathological “justice” as the day care center and recovered memory scares, and incidents like the Central Park Five jogger case, out-of-control prosecutors will very often double down on their initial terrible decisions to pursue weak or otherwise dodgy cases, for the basest of reasons…in losing, their careers would be tarnished. This does not even begin to address such abused practices as bribing so-called “jailhouse snitches” with favors, reduced sentences and even money in order to drum up testimony.

    There seems to be plenty of room in our current justice system for observing “BS”; perhaps a blog dedicated to flailing that sort of thing should ignore a few of these (there are several others)as well.

    • Wow. This blog post is about the usefulness of eyewitness testimony. You seem to have ignored that completely in your comment indicting its author on two points, one of which you admit she isn’t guilty of and the other a point not relevant to her discussion.

      And this:

      … I’d guess a person with time to blog wouldn’t appreciate this point.

      Is simply uncalled for and presumptuous.

      If you have something to say that actually relevant to the discussion of eyewitness testimony/memory…

  • GregB

    I guess *you* ignored my very first comment about her post.

    If the poster is making claims in buttressing a point, those claims should be subject to discussion I would think. Suggesting (as she did in the evidence presented) that 97% of defendants are guilty is just as absurd as believing that about half of eyewitness testimony is. Using such a misleading statistic in order to suggest that the justice system may not be “broken” seems to me uncalled for.

    And while the other issue was not “raised” by the article writer, it certain was included in her quote and allowed to pass without comment. If anything, it’s a *far larger* issue if one is truly interested in problems with the way we handle criminal matters.

    I thought the larger point of the blog (and the blogsite) was to call down misleading information, wherever one finds it? Are you suggesting that certain matters get a pass in order to prove some more interesting–to you–problem (and again, since you seem to have missed it, I agree the author’s overall point is important). I applaud all efforts to make the justice system more accurate in every sense…perhaps when we get there, we won’t continue to have absurd situations like the one we find ourselves in today, where we incarcerate more people on an absolute basis than does a country with 4 times our population (China). Getting eyewitness evidence right should be one of those efforts..

    There are many others…

    • This post was about eyewitness memory specifically so I did not get into other causes of wrongful convictions outside of mentioning forensics to make the point that that is not exempt from error. You seem to think that because I chose to limit the scope of the post to eyewitness memory that I am somehow blind to the host of other shortcomings that also need attention. And you also found it perfectly acceptable to draw conclusions about me personally based on that. I invite you to reacquaint yourself with the definition of bias.

  • I thought the larger point of the blog (and the blogsite) was to call down misleading information, wherever one finds it?

    Of course not. I’m suggesting that you’ll get a lot further if you don’t act like an ideological asshat who missed the point of the piece. Like it or not, that’s exactly how you come off.

  • Ed, essentially began a lengthy explanation about eyewitness memory errors, not quite addressing my criticism and then side-stepping it altogether, saying that it doesn’t matter how many have been wrongfully convicted …

    That is not what I was saying. What I was saying there was the matter of exactly which cause is #1 and which is #2 hardly seems all the important. What if Vandy, or whomever, said mistaken/wrong eyewitness testimony was the leading cause of wrongful convictions, causing 36.8% of them; but then you bring evidence that it’s not the leading cause because prosecutorial misconduct is actually 37.2%, how dare you misrepresent the facts! I think that would be a trivial point. I did not mean to side-step any points of yours, perhaps I did not understand you correctly.

    I do not think eyewitness testimony should be tossed out. Rather, I would endorse the recommendations of the Innocence Project and other legal experts in advising things like double-blind lineups, sequential not group, public and jury education, crackdowns on witness coaching, etc.., I also think that we need much more research here.

    The evidence I know about persuades me that eyewitness testimony is a leading cause of wrongful convictions. The national exoneration registry indexes 1427 exonerations. These are mostly non-DNA-related exonerations. Since that is a fairly large number and it covers all sorts of crimes, it seems a reasonably representative sample in most respects. Mistaken witness ID was a factor in 35% of those. The registry counts perjury and false accusation separately and it is a factor in 56% of cases, but I wonder if they separated out the cases where the accuser’s testimony was the “eyewitness testimony” or wasn’t. Those numbers give me pause.

    • Ed, absolutely the exact number are irrelevant, even if we could estimate them. The IP selects the cases they assist with and that selection bias may favor cases with certain causes of error that are easier to prove. I am definitely not making the Scalia argument here. There are too many cases for these to be isolated issues and the commonalities between cases suggests there are systemic problems that need to be addressed. The recommendations from the IP are from the same literature I have been summarizing (e.g. see the things I listed as system variables). Reform is needed (and this speaks to Greg’s comments too), but we won’t win the ear of the legal system by accusing them of deliberate misconduct. In the majority of these cases there’s no reason to suspect that these persons (witnesses, police, techs, judges, etc.) didn’t genuinely believe they had the culpable party. Many do resist acknowledging errors, but that’s as easily understood by cognitive dissonance theory.

      • Glad we have that miscommunication straightened out. I don’t think I disagree with any of that. I also see this particular problem as one of juror and witness psychology, not anyone’s misconduct. Blogs for public consumption are more useful in educating the public about memory and perception than they could be re: misconduct, which is something better addressed by reformers and experts within the system.

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