Criminal Justice

How Confirmation Bias Sends Innocent People to Prison

A new study of wrongful convictions shows the problem goes beyond misconduct by police and prosecutors.


Last week an Oklahoma judge freed Corey Atchison, who had spent 28 years in prison for a murder he has always said he did not commit, after concluding that he had been convicted based on the false testimony of "purported eyewitnesses" who had been "coerced" by prosecutors. The next day, an Idaho judge exonerated Christopher Tapp, who had served more than two decades for rape and murder, after DNA evidence implicated another man, who confessed to the crimes.

While cases like these often feature wrongdoing by individual prosecutors and police officers, a new study suggests the problem is deeper. After analyzing 50 wrongful convictions and other investigative failures, Texas State criminologists Kim Rossmo and Joycelyn Pollock found that confirmation bias, reinforced by groupthink and strong incentives to quickly identify the perpetrators of highly publicized crimes, figures prominently in the mistakes that send innocent people to prison.

Once police decide they have the right suspect, Rossmo and Pollock report in the Northeastern University Law Review, they tend to develop "tunnel vision" that obscures other possibilities. They become focused on building a case against the person they've decided is guilty, ignore or minimize countervailing evidence, and interpret ambiguous evidence in a way that supports their initial conclusions.

After Angela Correa, a 15-year-old high school student in Peekskill, New York, was raped and strangled to death in 1989, for example, police quickly settled on one of her classmates, Jeffrey Deskovic, as their sole suspect. "Suffering from tunnel vision, detectives pursued a single-minded course of action designed to get Deskovic to confess," Rossmo and Pollock write. "Police did not look for other suspects despite the presence of exculpatory physical evidence. In a classic confirmation bias pattern, detectives changed their theory of the case when the DNA test results came back excluding Deskovic."

Deskovic was convicted in 1990 based on a false confession he later retracted. For years the Westchester County district attorney, Jeanine Pirro, now a Fox News host who opines on justice, rejected Deskovic's requests to compare the DNA evidence against a criminal database. Deskovic was not exonerated until 2006, after he had served 16 years in prison, when a new D.A. approved testing that identified the actual perpetrator.

Christopher Tapp's conviction also was based on a false confession that was contradicted by DNA evidence, the pattern in about a third of the 367 cases in which the Innocence Project has used such evidence to clear people who were wrongly convicted. "Interrogations are not a quest for information," observes the Innocence Project's Vanessa Potkin. "The purpose is to get an admission."

In another case that Rossmo and Pollock examined, Bruce Lisker was wrongly convicted in 1985 of stabbing his mother to death at their home in Sherman Oaks, California. He was not released until 2009, at which point he had served 26 years, after a judge determined that he had been convicted based on false evidence, including the testimony of a jailhouse snitch police knew was unreliable.

"Investigators coerced a confession (quickly recanted) from the 17-year-old teenager through the offer of a plea bargain," Rossmo and Pollock write. "A rush to judgment followed by tunnel vision led to confirmation bias. Exculpatory evidence was ignored, while the alibi of an alternative and viable suspect was never checked despite inconsistencies in his story."

Confirmation bias is common and hard to root out. Rossmo and Pollock recommend training in "cognitive de-biasing," better evidence procedures, closer supervision, and a general awareness of cognitive biases and the factors that let them run riot.

Rossmo and Pollock also note that the "probable cause" standard for arresting someone, which creates momentum toward a conviction, is a low bar that does not require showing the suspect is more likely than not to be guilty. "A probable cause that is not probable is inconsistent with both language and mathematics," they write. "The most certain way to prevent a wrongful conviction is to minimize wrongful arrests of innocent people."

© Copyright 2019 by Creators Syndicate Inc.

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  1. Don't Talk to the Police:
    You Have the Right to Remain Innocent:

    Following Professor Duane’s advice won’t guarantee you don’t end up in prison, but you should know your rights. You have the right to remain silent and the police have to stop questioning you once you ask for an attorney.

    If they don't, you should still keep your mouth shut. Confessions are a major source of convictions.

  2. What a shocker - not. This is WHY the Founders set up our judicial system the way they did. Because even one innocent person in jail is an atrocity.
    Even without all these "studies" and "think tanks" they knew this shit. Imagine that.

    1. Not just an atrocity, but a threat.

      "It is more important that innocence be protected than it is that guilt be punished, for guilt and crimes are so frequent in this world that they cannot all be punished.

      "But if innocence itself is brought to the bar and condemned, perhaps to die, then the citizen will say, 'whether I do good or whether I do evil is immaterial, for innocence itself is no protection,' and if such an idea as that were to take hold in the mind of the citizen that would be the end of security whatsoever." - John Adams

      1. Adams’ Argument for the Defense: 3–4 December 1770, Founders Online, National Archives

        "We are to look upon it as more beneficial, that many guilty persons should escape unpunished, than one innocent person should suffer. The reason is, because it’s of more importance to community, that innocence should be protected, than it is, that guilt should be punished; for guilt and crimes are so frequent in the world, that all of them cannot be punished; and many times they happen in such a manner, that it is not of much consequence to the public, whether they are punished or not. But when innocence itself, is brought to the bar and condemned, especially to die, the subject will exclaim, it is immaterial to me, whether I behave well or ill; for virtue itself, is no security. And if such a sentiment as this, should take place in the mind of the subject, there would be an end to all security what so ever."

        [Original source: The Adams Papers, Legal Papers of John Adams, vol. 3, Cases 63 and 64: The Boston Massacre Trials, ed. L. Kinvin Wroth and Hiller B. Zobel. Cambridge, MA: Harvard University Press, 1965, pp. 242–270.]

        1. That's a good one to pull out when people bitch about the system letting (assumed) guilty people go free over technicalities and because of misbehavior of cops.
          No legal system can work well if most people don't trust it and respect the laws it enforces.

  3. "The most certain way to prevent a wrongful conviction is to minimize wrongful arrests of innocent people."

    Which just changes the level at which to solve the problem, not a solution to the problem.

    1. The solution is executions by vigilantes against those who put innocent people in jail.

      1. What if they get the wrong person and suffer from the same kinds of confirmation bias?

        1. Then we get new vigilantes to execute the original vigilantes. Its a flawless plan!

  4. Sad to think that some of this stuff is news to some people. How old is that YouTube video about why you never talk to police? There's no excuse for being ignorant of how the criminal justice system works versus how it's supposed to work in theory. Warrants are rubber-stamped, grand jury indictments are rubber-stamped, cops want to clear their case files by whatever means necessary, prosecutors want convictions more than they want justice, the judges are too-frequently former prosecutors and they all "know" that the nearest suspect is the guilty party 99.999% of the time so why do we even need this charade of an investigation and a trial? It's not a mean evilness, it's just a banal evil. It's not that they deliberately want an innocent person to suffer, it's just that they don't give a shit whether or not an innocent person suffers.

    1. Truly. You would think that after cases like the central park five, the Duke lacrosse players, and the supposed child sex abuse cases out of daycare centers in which children were browbeaten into testifying about sexual abuse that never happened, Confirmation bias would be established fact.

      And as for interrogations, remember the first episode of Homicide, when Frank Pembelton tells young detective Bayless that the purpose of an interrogation is to sell a confession in the same way that a used car salesman sells a car.

      1. Confirmation bias is pervasive and almost impossible to spot from the inside. Just look at politics - that's just about all there is to politics, yet even very smart people are susceptible to the confirmation bias that results from team-think and believe that their side is always right and the other side is always evil.

        There's even an experience-based faith in confirmation bias in the judicial system... why do you think opening arguments are so important to lawyers? They want to set a picture in the juror's minds so that they will cherry-pick their way through the evidence that is presented - elevating things that auger in their direction and discounting things that don't.

        That's how you end up with verdicts like the McMartin Preschool Case and Little Rascals Preschool. That's why prosecutors spend so much time telling the jury how horrible the crime is. They want them to feel like they have to hold someone responsible... and then confirmation bias takes over.

        If you listen to opening arguments in big trials, most of the stuff presented by the prosecution is irrelevant. The victim was really wonderful - had a family, was universally loved. The crime was gruesome and particularly sadistic... All irrelevant to the task at hand, which is to prove that a crime was committed and that the defendant is the person who did it. It only exists to push the minds of the jury into a "we have to hold someone accountable" frame where they'll be looking for reasons to convict instead of looking for reasons to acquit.

  5. While we have the technology to drastically reduce wrongful convictions, trials in general and all crime, we’re too stupid and pig headed to use it.

    Then we whine and complain as we dwell in our ignorance.

    We have the technology to effortlessly record all our observations and immediately store them safely in the cloud. We just don’t have the human right to safely protect ourselves in this way.

    Because corrupt dipshits need to lie. Our economy is based on it.

  6. Confirmation bias is common and hard to root out. Rossmo and Pollock recommend training in "cognitive de-biasing," better evidence procedures, closer supervision, and a general awareness of cognitive biases and the factors that let them run riot.

    Or why not just outlaw confirmation bias?

    1. If Indiana could legislate that Pi = 3.14 then I suppose anything is possible.

      1. Heck, for laying out a flower bed in the backyard 22 / 7 ~= pi works good enough.

  7. I noted in the article that several of the suspects had confessed and that they were very young when they confessed. This makes me consider whether confesses should be accepted for people under say 21 years of age. We are talking about young people who likely don't have the mental awareness to stand up to the pressures police or prosecutor may apply. These confessions often then substitute for hard evidence. The confession can then contribute to the bias as a juror may accept the confession in absence of hard evidence.

    1. Any juror is going to accept a confession. That's as cut and dried as it gets. It would take a lot to overcome a video of the defendant saying "I did it." That isn't even eyewitness testimony. That's about as ironclad as you are going to get. At that point you don't need forensics, DNA, blood spatter analysis, video... you have the defendant saying he did it. Case closed.

      Very few people are going to understand that the police can wear down people and make them believe that saying what they want to hear will make it all go away. The numbers at the innocence project on this are stunning. False confessions are involved in a huge number of wrongful convictions - and the possibility that DNA evidence is going to turn up is extremely remote. So we only have this percentage for cases of rape and in rare instance, murder. But you have to believe that there are similar percentages in armed robbery cases, etc. Which is pretty darned scary.

      1. Juries are like democracy that way: the worst system except for all the other ones.

      2. Another option - make all confessions inadmissible and make the prosecution prove its case through evidence.

        1. Or at least require that confessions be repeated in open court. Informing the jury that false confessions happen pretty frequently wouldn't be a bad idea either. Juries too often seem to presume that the police are more interested in getting the right person than closing the case.

      3. No juror should be allowed to see any confession not made in open court.

    2. All confessions should be on video.

      All minors should not be interviewed by police until a parent is present and they have a right to an attorney present.

      1. "All confessions should be on video."
        And the entirety of all interrogations should be required to be shown, so that the jury can see the pressure the defendant was placed under before "confessing".

  8. One big help would be to hold these prosecutors and cops accountable. Withholding exculpatory evidence? Refusing to check DNA evidence? You have framed someone. You should be held liable by being punished as your victim was (or could have been) punished.

    Cops and prosecutors would think long and hard about this kind of perjury if they knew the punishment was years in prison. Of course, some would put more work into covering up their malfeasance, but that would just be stronger evidence of their intentions.

    Some cops and prosecutors wold also be too cautious and not want to arrest or prosecute anybody. So be it -- they'd be fired for laziness or incompetence.

    1. I like this solution.

      The implementation question, unfortunately, is who will enforce it? Police have already demonstrated great difficulty in holding their own accountable. I think you'd have to include some private right of prosecution for it to work. Private prosecutions are extremely rare in the US these days. The UK seems to manage it, though.

  9. Another problem is that suspects are kept in the dark about evidence and investigations. Police are hardly unbiased, as shown; the proper counter balance is to bring suspects into investigations as full partners as soon as they are identified. The moment something points to somebody, they should be able to weigh in on all evidence immediately, including be in on witness interviews, evidence testing, etc.

    The idea that defendants can't interview witnesses until a trial six months or a year later is ludicrous. Memories have long since been frozen into place by repeated rehearsals. The time to dispute and cross-examine is right from the start, not only because the memories are fresh, but because this confirmation bias steers all following investigations down the wrong road, and by then there's too much sunk cost and too much face to save for any cop or prosecutor to ever back up and rethink things.

  10. I bet you would probably have a lot fewer dirty, corrupt, prosecutors if they had to personally compensate their innocent victims out of their own pockets!

  11. Despite the presumption of innocence in criminal cases, and that the plainitff in civil matters typically bears the burden of proviing his or her claim, I can't help but think that it's always better to be the accuser. For one thing, the accuser in both civil and criminal matters gets the first word (speaks first during opening argument) and the last word (speaks last duirng closing argument). This makes some sense in a legal context because the accuser must carry his or her burden of proof, but it ignores the fact that people generally tend to remember either the first or last things people say.

  12. A big part of the problem is that cops are fat retards. Find me a cop who made straight-As in high school. Or kindergarten.

    1. One of my cousins made A's at Stanford Law School and then became a cop (first beat then detective now prosecutors office) after he hated corporate law (but paid off the debt).

      Course I don't know what his grades were in kindergarten or high school. Or even what sort of donuts he prefers.

      course you also know confirmation bias applies to everyone. Not just fat retards. right?

      1. And therein you nailed it: Tony is the problem and his take on the law was gleaned from where? School? Parents? If Tony were arrested he would hang himself in short order and no doubt he is one who thinks 'remaining silent' is evidence of guilt. (thank you Hollywood) A jury cannot be told a defendant exercised his/her Rights under the 5th.
        But... Being called "Tony" indicates guilt does it not? Tony and his brother Guido are caught with a case of stolen cigarettes so they are in the mob right? Separate them and tell each that the other is talking then you have two brothers ratting each other out and the cigarettes were planted by police because police wanted to seize the cool car they were driving. The DA offers a plea and they take it but their futures are now bleak but the tyrannical court system and its un-Constitutional inhabitants are doing very well for themselves which you point out using your cousin's experiences in that realm.
        Bottom line is to remember this a Constitutional Republic not a democracy where there was no mention of courts or cops in the Constitution and cops are not your friends nor do they serve or protect. They have twisted the Law of the Land into a nightmare of Latin phrases spoken only to each other in courtrooms while ignorant juries decide the fate of ignorant defendants who will be financially ruined when it is over. The jurors will get a stipend and a headache and cops do get paid very well in a job that is not really that dangerous and the DA has unlimited access to taxpayer funds to screw the taxpayer in court.
        Bottom line is we can do away with the criminal court and police forces and revert right back to what The Constitution intended if not for those among us who cannot be Independent and need rulers to ruin it all for everyone else.
        The Bill of Rights is all we have and the 5th Amendment is just as important as the others. Do not allow your protections and Rights to be diminished by other's protests.
        We are now seeing people protesting against their Rights for the first time in history. It is no accident they are high (public) school students and their leader is the son of an FBI agent. The son is an idiot and has been given a free pass to an Ivy League school after being rejected by 4 normal schools (schools I know are not 'normal' anymore either but I am only 65 and still learning). FBI director J. Edgar Hoover was a brilliant dictator and most do not know that fact thus proving his brilliance. Witness: A fierce gun battle in Los Angeles put gun control in the forefront again while the LAPD's history of rampant corruption and racism is largely forgotten. Overlooked is that the whole incident was over a bank robbery! LAPD enforcing federal law!? Why do they have to enforce federal laws concerning paper money? Gun free zones is federal law so local police have no jurisdiction there either and here we are scratching our heads about the tyranny we do not realize- unable now to what was once freely buy a Thompson sub-machine gun because of John Dillinger, J Edgar and FDR (D, New York) and the role of paper money once backed by gold but now backed by "trust" in government! (cue laugh track now) We must endure the constant beating over our heads all the nonsense this small group inflicts on all. And paper dollars.
        Now it should be easier (Tony, I am looking at you) to remember DO NOT talk to police, ever, never. (I am not an attorney )
        Tony, go back to school because those "retards" have got you by the short-hairs 24/7!
        We should not be trying to repair something we do not need. We have prisons full of people that do not need imprisonment. We have laws that are based solely in racism. We have career politicians which violates the very essence of our Constitution. Politicians all seem to have law degrees. In the top 10 career choices of sociopaths are "lawyer" and "police officer" and letting a sociopath run your life is the biggest mistake one can make. "Surgeon" is on the list but "doctor" is not. Why? Surgeons have no problem with slicing open a living human... Reality is contrary to common-sense and common-sense does not exist and what we think should be right often is opposite. Those that profit from our mistaken beliefs know enough to keep us in control and in the dark. They are experts in propaganda. It is no accident or fluke that television sets are wonders of technology today compared the 1950s and in 1950's dollars televisions today are next to being free of charge and would cost $4000 today if they had kept pace with the dollar. Television delivers the 'news' that drives the economics of politics and law. Television is cop shows and lawyer shows galore, filled with misinformation with news at 11, "eyewitness news", they lie, they saw nothing and eyewitnesses are totally unreliable. I rest my case your honor.
        I forgot to mention "presumption of innocence"... whatever happened to that?

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  14. It's where the incentives are. The incentive is to close the case, get a conviction, right or wrong. If there are the real criminals left out there - well, there are always criminals out there anyway. And if we put people in authority who hold to those views, that's the kind of justice we will get.

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