decision making of juries psychology essay

The psychology of jurors’ decision-making

It’s your job to know how they think, what persuades and what puts them off.

Jurors make decisions just like other human beings do, but they do so in an environment that is different from everyday individual decision-making. The conditions of trial and the group setting create some demanding characteristics that can lead to the use of cognitive shortcuts or unconscious biases influencing decision-making, and group dynamics can also play a role. What is not true is the belief that jurors are not intelligent enough to make decisions in complex cases, that their decisions are arbitrary and baseless, or that passion drives every verdict. Going into trial with that view of the jury pool will impact the way you present your case, to your detriment.

If the jurors don’t understand the case or don’t base their decision on the relevant evidence, that is in part your fault. It is your job as attorneys to know your audience, to know how they think, what is persuasive to them and what is off-putting. It is your job to make your case interesting, understandable, and compelling. To do that, it is useful to become familiar with the way human beings make decisions generally, and how the trial setting and case themes interact with those processes.

We’ll start with discussing cognitive psychology concepts known as cognitive biases. While we usually use the word “bias” to refer to an undesirable or negative trait, cognitive biases help human beings survive in a high-information world. We all have these cognitive biases; we all use them. Learning about these biases and how they may influence your case presentation will help you become better advocates for your clients.

Confirmation bias

Confirmation bias, also known as “my side” bias, is the tendency to seek out, attend to, and better recall information, for example, evidence and arguments, that confirms one’s preexisting attitudes and beliefs while at the same time discounting or ignoring information that is contrary to one’s preformed opinions. 1 When evidence is ambiguous – as it often is in cases that make it to trial, it is interpreted in a way that confirms the initial belief.

Confirmation bias is strongest concerning issues that are emotionally charged, and beliefs that we think form the basis of our own self-identity. Politics is the prime example. Conservatives listen to news outlets that support their views; Liberals do the same. We purge our Facebook pages of people whose opinions are different than ours.

Confirmation bias plays a significant role in decision-making and therefore it underscores the importance of jury selection. Every human being engages in confirmation bias. Intelligence, station in life, age, race, gender – none of it matters. Confirmation bias is why 12 people can hear the exact same case and come to vastly different interpretations of what happened, who was at fault, and what the damages should be. You will not change the mind of someone with strong views against essential elements of your case – not in jury selection and not during the trial.

What you must do instead is identify those whose personal life experiences – the most influential factor in shaping attitudes and beliefs – are problematic for your case. This is not accomplished by asking the jurors if they can be fair and follow the law. It is not accomplished by asking questions that begin with “Do you understand…” or “The judge will explain that the law is…” It is not accomplished by “asking” jurors hypothetical questions that only seek to advance themes or gain meaningless commitments. And in fact, asking some of these types of questions, which jurors may see as having little to nothing to do with the facts of the case, can cause them to think poorly of you. 2

The stereotypes

Confirmation bias also affects the decisions attorneys make in jury selection. There are long established stereotypes based on demographics like race, gender, age and education about who makes a “good” defense juror and who makes a good plaintiffs juror. There is a belief that higher status, higher educated, more intelligent, higher income, white male jurors are defense jurors because they will decide things more rationally, and base their decisions only on “evidence” and “logic” instead of “emotion.” There is the belief that lower-educated, lower-status, minority jurors and females will be pro-plaintiff because they will be more emotional and more empathetic, and that they will award more damages because they don’t understand the numbers. Preservation of these stereotypes in deciding who to strike and who to keep (even in the face of contradictory evidence) is not only illegal per Batson v. Kentucky 3 , but making demographic-based jury selection decisions can also be seriously detrimental to the outcome of your case. Stereotypical thinking along demographic lines will lead you to keep bad jurors and strike good ones.

For the last 20 years I have encountered this stereotypical thinking, even amongst some of the best trial lawyers in the country. I see attorneys ignoring dangerous statements coming from the juror’s own mouth about experiences, attitudes and beliefs that would affect their impartiality, all because of the potential juror’s demographics. Every human being has confirmation biases, and attorneys are no exception. Be cognizant of your own biases when selecting jurors. Ask yourself if you would feel the same way about the answer a juror has given if it was someone of a different demographic profile who said it. If the answer is no, pay attention to the words and the sentiment and react accordingly. Every juror is prone to confirmation bias, regardless of their intelligence, education level, or socioeconomic background. If they are telling you that they have pre-formed beliefs or strong views about relevant case issues that are detrimental to your case, confirmation bias will make it very difficult to change their mind.

If everyone has confirmation bias, how can we ever select jurors who will be impartial? There is some evidence to suggest that making people aware of the tendency for confirmation bias can reduce their tendency to fall victim to it. Talking to jurors about how the process works and asking them to be aware of the potential for it to happen to them may result in them actively working to keep an open mind to the evidence and arguments presented. 4

Research has also demonstrated that people with high confidence levels are less susceptible to confirmation bias because they are open to and actively seek out contradictory information when forming arguments. 5 Their self-identity is less tied in to the preservation of their beliefs.

Fundamental attribution error/defensive attribution

The role of jurors in a civil trial requires them to make attributions about causality and responsibility. Psychologists have developed a distinction between two types of attributions for behavior, 1) internal or dispositional attribution, which focuses on characteristics of the person, or 2) external or situational attribution, where the focus is on the situation or circumstances. 6

When making decisions about the cause of negative events that happened to others we are most likely to form internal attributions, meaning that we are more likely to scrutinize the behavior of the individuals involved as opposed to the circumstances. On the contrary, we are more likely to place blame for our own misfortunes on circumstances, or the situation. This is what is known as the Fundamental Attribution Error. 7

A subset of the fundamental attribution error is Defensive Attribution. 8 This is a cognitive bias we use to protect ourselves from the fear that a negative event that happened to someone else could happen to us. When we hear about a tragic outcome, we want to psychologically distance ourselves from the belief that we could befall a similar fate. How do we do that? We focus on the actions, motivations, and behavior of the victim as opposed to the circumstances. We say, “If I were in that situation I would have checked my mirrors, crossed the street, notified HR, etc.” The more similar we are to the person who has experienced the bad event, or the more likely it is that we could find ourselves in similar circumstances, the more likely we are to engage in defensive attribution. Plaintiffs’ attorneys must be constantly looking for ways in which potential jurors might be personally threatened by what happened to the client and therefore seek to distance themselves psychologically from a similar fate by focusing on what he or she did to cause or contribute to the situation.

Attribution Theory is another important construct to be aware of in jury selection. Are jurors similar to your client likely to be more empathetic and favorable? Or not? There is a sizable body of literature examining the impact of litigant/juror similarity in terms of both demographics and personality variables on verdicts. 9 The belief behind the early research was that similarity results in attraction, so similarity would also result in more favorable treatment of a similar party. That certainly seemed to be the case in some studies, and many trial attorneys hold the belief that a juror who can “identify” with the client is a good one.

There is, however, a flip side to similarity: that is, similarity and rejection, as opposed to liking. This phenomenon, known as the “black sheep effect” can occur when a similar other either has negative attributes or has suffered negative consequences or outcomes. 10 This causes other “in group” members to want to distance themselves from the offending party. This results in harsher treatment by similar others than by those who are dissimilar to the target person. This is often the result of the psychologically protective mechanism of defensive attribution. We don’t want to believe the same thing could happen to us, so we denigrate the similar other, thus differentiating him or her from ourselves.

How does defensive attribution play out in trials?

A juror with similarity to a litigant is always a risk. She can be great for you, or she can be your most dangerous juror. On the one hand, similarity to a litigant, for example the plaintiff, can lead to empathy. Having undergone a similar situation, the juror knows how hard it was, how awful it was, how painful it was, etc. Or, in the case of the defendant, maybe the juror’s family was sued for something she felt was unfair, or maybe she has a small business and is overly concerned with litigation, resulting in empathy to the defendant’s situation.

Identification can also, however, lead to rejection. Someone who was harmed in an accident, or lost their job because of unfair treatment and didn’t receive any compensation for it can be bitter and judgmental. Even though their claim was just, this person obviously brought this upon themselves. Similarity-rejection can happen to civil defendants too. Someone who works in the same industry may compare how things work at their company as opposed to the defendant and say, “We would never have done XYZ,” or, “Where were the written policies?” “Why wasn’t HR contacted?”

Lastly, similarity can also result in denial. Someone who has experienced a similar situation as a plaintiff can downplay the impact it would have on someone (because they chose not to sue, or didn’t get sued), or downplay the need for compensation. For example, “I have a bad back, but that’s just part of getting old.” “Even if she weren’t in that car accident she could have suffered from memory loss.” This type of juror might become an “expert” on the jury, telling others the real extent of the pain, insinuating that the plaintiff is exaggerating.

Cognitive dissonance

Cognitive Dissonance is the state of being uncomfortable when our actions don’t comply with our beliefs. To reduce this state of mental discomfort we either change the underlying belief (less likely) or justify our actions through rationalization, minimization, or discounting. 11 You can manage cognitive dissonance in jurors when you let them believe they are coming to a decision on their own instead of doing something that you tell them they should do. We are more motivated to act based on things we think are our own ideas instead of those coming from someone we believe is actively trying to persuade us.

Hindsight bias

Hindsight Bias is also known as the “I knew it all along” effect or “Monday morning quarterbacking.” This refers to our tendency to, after all information is known about an event, perceive it as having been foreseeable and/or preventable, regardless of the surrounding circumstances. 12 This cognitive bias can play a significant role in jury decision-making. Knowing what we all know now, after the event, actions that could have prevented or mitigated the outcome are apparent. After an auto accident, we can all think of what we would have done differently and how that would change an outcome.

A doctor whose care resulted in an adverse outcome “should have known” that their choices would result in an adverse outcome. Hindsight bias is most detrimental to the party that is perceived as having the ability to prevent the bad outcome.

Hindsight bias can be reduced by using counterfactuals and putting the juror at the beginning, in a position of foresight. 13 Counterfactuals cause decision makers to think about alternative outcomes based on what was known at the time that a choice was made. The use of “If only” statements are effective in countering hindsight bias. For example, “If only the driver had chosen to drive the speed limit,” “if only the company had installed the low-cost part,” “if only the manager had done a proper investigation,” etc.

Trial presentation and jury decision-making: The story model

Why is the Story Model effective in trials? Because we all use stories to make sense of the world. It is how we best learn and categorize information. A story creates a “schema” or narrative of what we believe happened, and then through other cognitive biases, we tend to filter the evidence and arguments through this schema. 14   Jurors come to trial wanting to know what happened. A good story answers this question in the way that is most beneficial to your client but also fits the evidence most succinctly. Each element of the story is important to think of when preparing your case. If there are holes in the narrative, jurors will fill them in on their own. 15 The story has a setting. It has a beginning or the initiating events; characters, each of whom has motivations to act; actions or turning points; consequences and outcomes of actions; and a conclusion, which the jury ultimately decides. 

The story structure also improves comprehension and memory and makes sense in terms of determining cause and effect, which is what jurors are mostly tasked with. 16 It is familiar. An engaging story draws people in and makes them care about what happens. It is less like attending a lecture and more like watching a film or reading a book. A legally strong case may fail at trial if there is not a viable, compelling human story that shapes the case presentation.  This is not to say jurors don’t follow the law; they work hard and for the most part do the best they can with the limitations imposed on them by arcane jury instructions. But jury instructions, like much within the trial setting, can be ambiguous and open to interpretation. The story that jurors form about what happened and why is what drives the verdict, not the instructions.

The law and the instructions become a part of the story during closing arguments. More recent research has found that both sides do better employing a legal expository structure for closing as opposed to a strict narrative. 17 What does this mean?

The Legal Expository Structure is a point/counterpoint structure that is often employed by the defense. This involves comparing plaintiff arguments/evidence to defense argument/evidence point by point, structured around the instructions and legal elements as opposed to only chronological order. 18 This works well for both sides in closing because it gives context to the evidence within the rules for decision-making and focuses jurors on evidence that supports their side, based on those rules.

Defendants typically use the legal expository structure for both opening and closing and research has found that this works for them even better than a pure narrative structure. 19 Why might this be? One theory is that because of primacy effects, the jurors will develop a schema or story of what happened based on the plaintiffs’ opening. The defense, rather than simply retelling the story from their point of view, challenges or reinterprets the story that plaintiffs have told.

A mixed structure is likely best for both sides. 20   Plaintiffs should anticipate and counter defense arguments in their openings, and defendants need to make jurors see their clients as being part of a coherent, human story. Without story elements like setting and goals a narrative seems incomplete and therefore less persuasive. In closing arguments put the story in the context of the law and instructions. Be sure to tell them how to vote to side with you!

When telling your story, the initial focus should not be on your client. The focus should be on the other side and their motivations, poor choices, and actions. Why? Because trials occur when there was a negative outcome for someone. Both the fundamental attribution error and defensive attribution teach us that people want to blame the actors for bad things that befall them, and credit the situation for good things that occur. They will begin the case by looking to see who was at fault. The plaintiff’s case must be about the defendant’s conduct. This is where you want the jury’s attention. The idea is that the defendant’s actions set up a situation that could have harmed anyone – your client just happened to be the one who suffered this time. 

For example, let’s say you have a case involving allegations of a dangerous roadway condition that resulted in a fatal accident. One approach from the plaintiff perspective is to begin like this: “On Monday morning October 4, 2016, James Smith left his house to go to his job of 20 years at the Bank of America where he worked as an accounts’ manager. He was driving along Broadway, his usual route, going the speed limit. He needed to make a left-hand turn at Green Street but he had a difficult time determining if there was oncoming traffic because the roadway was designed in a way that made it hard to see, and there was overgrown brush on the side of the road. He waited until he thought it was clear and then turned. He was struck by an oncoming vehicle and was severely injured.”

What are you focused on at this point – the roadway or the actions of Mr. Smith? Mr. Smith.

Attorney presentation style

Don’t tell the jurors what to do or what to think. Persuasion is much more effective when you lay out the pieces and lead them to conclude on their own. When jurors come up with themes and analogies and decisions about the behavior of the parties, it is much more powerful than when you tell it to them.

Two things jurors hate most of all are the perception that their time is being wasted and the belief that the attorneys are being manipulative, slick, or condescending. In a recent jury selection the attorneys made mini openings before the jurors completed a questionnaire. One juror wrote on her questionnaire in response to a reason she couldn’t be fair and impartial: “I felt like the defense attorney addressed the room as if we are children. I saw through his attempt to humanize his client. I’m not a huge fan of his technique so far. If it continues, he may swing me the other way.”

I’m often asked about how important it is for an attorney to be “likeable.” Liking the attorney does not necessarily result in a favorable verdict. But dislike for an attorney based on demeanor, trial tactics, and presentation style has an impact. This is especially true if the behavior coincides with attributes/traits of the case and the underlying participants. If the plaintiff is portraying a defendant as being evasive, hiding evidence or being less than forthcoming in testimony, then lawyers who do not appear open and honest will solidify that perception. If a plaintiff’s attorney comes across as not caring for the client that they represent, or unknowledgeable about their client’s personal information, then they fall into the stereotype and frequent defense theme that this is attorney-driven litigation.

Do not talk down to jurors. Do not go into trial thinking they are not as smart as you or will never understand the nuances of your case. If they don’t understand, it is because you are not doing your job correctly. There is a difference between simplifying a story and using real-world analogies to illustrate difficult concepts and being condescending; jurors are smart enough to notice.

  Editor’s note: Portions of this article appeared in the Fall/Winter 2017 issue of Voir Dire magazine, a publication of the American Board of Trial Advocates. The article is reprinted with permission.

1    Raymond S. Nickerson, (1998) Confirmation Bias: A Ubiquitous Phenomenon in Many Guises . 2(2) Rev. of General Psych, 175-220.

2    For example, in a recent case a seated juror who was listening to jury selection of alternates told the bailiff that she had been offended by the questions the defense attorney had asked and that she now believed she may be biased against him.  When questioned, it was revealed that the offending question was one of those questions attorneys ask that are hypothetical or “trick” questions designed to prove a point.  He had asked her if she enjoyed television and movies and then if she a) understood the difference between television and reality and whether she preferred one over the other.  Arguably his goal was to get the jurors prepared for the fact that some testimony would be presented only through video.  The form of the question, however, was the wrong way to go about inquiring on this issue.  The juror went on to explain that she felt embarrassed that she was the only juror asked this question, and had concluded that the attorney must think that she is stupid because he didn’t ask her about any of the issues in the case that other jurors had been speaking about.  She said, “I was hoping to talk about my views on the issues, but you only asked me this question and you didn’t ask anyone else and I was offended by that.  Why did you do that?”

3    Batson v. Kentucky, 476 U.S. 79, 106 S. Ct. 1712, 90 L. Ed. 2d 69 (1986).

4    Keith Stanovich, Richard West, & Maggie Toplak (2013).  Myside Bias, Rational Thinking and Intelligence .  22(4) Current Directions in Psychological Science 259-64. 

5    Id.   

6    Fritz Heider (1958). The Psychology of Interpersonal Relations. New York: Wiley; Harold Kelley (1967). Attribution Theory in Social Psychology.   In D. Levine (ed.), Nebraska Symposium on Motivation (Vol. 155, 192-238). Lincoln: University of Nebraska Press. 

7    Lee Ross (1977.  The Intuitive Psychologist and His Shortcomings: Distortions in the Attribution Process.  In L. Berkowitz, Advances in Experimental  Social Psychology. (Vol. 10, 173-220).  New York: Academic Press.   

8    Kelley Shaver (1970).  Defensive Attribution: Effects of Severity and Relevance on the Responsibility Assigned for an Accident.  14(2) Journal of Personality and Social Psychology, 101-113; Jerry Burger (1981). Motivational Biases in the Attribution of Responsibility for an Accident: A Meta-Analysis of the Defensive Attribution Hypothesis, 90(3) Psychological Bulletin, 496-512. 

9    James Davis, Robert Bray & Robert Holt (1977). The Empirical Study of Decision Processes in Juries: A Critical Review. In. J. Tapp & F. Levine (Eds.) Law, Justice, and the Individual in Society 326-361. New York: Holt.

10 Jose Marques (1990).  The Black Sheep Effect: Out Group Homogeneity in Social Comparison Settings. In D. Abrams & M.A. Hogg (Eds.), Social Identity Theory: Constructive and Critical Advances 131-151.  London: Harvester Wheatsheaf.

11 Leon Festinger (1957) A Theory of Cognitive Dissonance.  California: Stanford University Press.

12 Baruch Fischoff & Ruth. Beyth (1975) I Knew it Would Happen: Remembered Probabilities of Once-Future Things. 13 Organizational Behaviour and Human Performance 1-16. 

13 Merrie Jo Stallard & Debra Worthington (1998). Reducing the Hindsight Bias Utilizing Attorney Closing Arguments . 22(6) Law and Human Behavior 671-683. 

14 Nancy Pennington & Reid Hastie (1992). Explaining the Evidence: Tests of the Story Model for Juror Decision- Making. 62(2) Journal of Personality and Social Psychology 189-206.

17 Shelley Spiecker & Debra Worthington (2003).  The Influence of Opening Statement/Closing Argument Organizational Strategy on Juror Verdict and Damage Awards. 27(4) Law and Human Behavior, 437-456.

Copyright © 2024 by the author. For reprint permission, contact the publisher: www.plaintiffmagazine.com

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Article contents

Jury decision-making.

• R. Scott Tindale R. Scott Tindale Department of Psychology, Loyola University Chicago
•  and  Kelsey Berryman Kelsey Berryman Loyola University Chicago
• https://doi.org/10.1093/acrefore/9780190236557.013.294
• Published online: 22 February 2023

A key aspect of Western civilization’s conception of justice is the citizen jury. Juries make decisions concerning guilt or innocence of committing a crime and on liability in civil matters. Psychologists who study group decision-making have focused a fair amount of their attention on juries. Researchers have looked at all aspects of jury trials to better understand how various characteristics and procedures influence jury deliberations and verdicts. Many different models of jury decision-making have been proposed, and the implications of the models have guided a fair portion of the research in the field. Jury research has focused on how juries are formed and how the members are selected. Research has also focused on trial characteristics, types of evidence, and potential biases that can influence both jurors and jury verdicts. In addition, much research has focused on the deliberation process itself. In the early 21st century, research has begun to look at how juries are defined and used in different countries and cultures.

• criminal trial
• civil trial
• death qualification
• deliberation
• decision rule

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date: 17 May 2024

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The promise of a cognitive perspective on jury deliberation

• Emerging Trends in Psychology and Law Research
• Published: April 2010
• Volume 17 , pages 174–179, ( 2010 )

Cite this article

• Jessica M. Salerno 1 , 2 &
• Shari Seidman Diamond 2 , 2  

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Despite much psychological research regarding jury decision making, surprisingly little is known about the deliberation process that gives rise to jury verdicts. We review classic jury decision-making research regarding the importance of deliberation and more recent research, investigating deliberation and hung juries, that challenges the view that deliberation does not have an important impact on verdicts. We advocate greater attention to potential cognitive processes during deliberation that might explain the transition between predeliberation preferences and a jury’s ultimate verdict. We then review cognitive work in the group context generally, and the jury context specifically, illustrating the promise of a cognitive perspective on jury deliberation. Finally, we identify cognitive phenomena likely to be particularly valuable in illuminating deliberation behavior.

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Avoid common mistakes on your manuscript.

Arizona Rule of Criminal Procedure § 22.4 (2007).

Basden, B. H., Basden, D. R., Bryner, S. , & Thomas, R. L. (1997). A comparison of group and individual remembering: Does collaboration disrupt retrieval strategies? Journal of Experimental Psychology: Learning, Memory, & Cognition , 23 , 1176–1189.

Article   Google Scholar  

Brekke, N. J., Enko, P. J., Clavet, G. , & Seelau, E. (1991). Of juries and court-appointed experts: The impact of nonadversarial versus adversarial expert testimony. Law & Human Behavior , 15 , 451–475.

Google Scholar  

Castore, C. H. (1972). Group discussion and prediscussion assessment of preferences in the risky shift. Journal of Experimental Social Psychology , 8 , 161–167.

Chapman, G. , & Bornstein, B. H. (1996). The more you ask for the more you get: Anchoring in personal injury verdicts. Applied Cognitive Psychology , 10 , 519–540.

Clark, S. E., Hori, A., Puthnam, A. , & Martin, T. P. (2000). Group collaboration in recognition memory. Journal of Experimental Psychology: Learning, Memory, & Cognition , 26 , 1578–1588.

Dann, B. M. (1993). “Learning lessons” and “speaking rights”: Creating educated and democratic juries. Indiana Law Journal , 68 , 1229–1279.

Davis, J. H., Kerr, N. L., Atkin, R. S., Holt, R. , & Meek, D. (1975). The decision processes of 6- and 12-person mock juries assigned unanimous and two-thirds majority rules. Journal of Personality & Social Psychology , 32 , 1–14.

Davis, J. H., Stasson, M. F., Ono, K. , & Zimmerman, S. (1988). Effects of straw polls on group decision making: Sequential voting pattern, timing, and local majorities. Journal of Personality & Social Psychology , 55 , 918–926.

Devine, D. J., Clayton, L. D., Dunford, B. B., Seying, R. , & Pryce, J. (2001). Jury decision making: 45 years of empirical research on deliberating groups. Psychology, Public Policy, & Law , 7 , 622–727.

Devine, D. J., Olafson, K. M., Jarvis, L. L., Bott, J. P., Clayton, L. D. , & Wolfe, J. M. T. (2004). Explaining jury verdicts: Is leniency bias for real? Journal of Applied Social Psychology , 34 , 2069–2098.

Diamond, S. S. , & Casper, J. D. (1992). Blindfolding the jury to verdict consequences: Damages, experts, and the civil jury. Law & Society Review , 26 , 513–557.

Diamond, S. S. , & Levi, J. N. (1996). Improving decisions on death by revising and testing jury instructions. Judicature , 79 , 224–232.

Diamond, S. S., Rose, M. R. , & Murphy, B. (2006). Revisiting the unanimity requirement: The behavior of the non-unanimous civil jury. Northwestern University Law Review , 100 , 201–230.

Diamond, S. S., Rose, M. R., Murphy, B. , & Smith, S. (2006). Juror questions during trial: A window into juror thinking. Vanderbilt Law Review , 59 , 1927–1972.

Diamond, S. S. , & Vidmar, N. (2001). Jury room ruminations on forbidden topics. Virginia Law Review , 87 , 1857–1915.

Diamond, S. S., Vidmar, N., Rose, M. R., Ellis, L. , & Murphy, B. (2003). Jury discussions during civil trials: Studying an Arizona innovation. University of Arizona Law Review , 45 , 1–81.

Eakin, D. K., Schreiber, T. A. , & Sergent-Marshall, S. (2003). Misinformation effects in eyewitness memory: The presence and absence of memory impairment as a function of warning and misinformation accessibility. Journal of Experimental Psychology: Learning, Memory, & Cognition , 29 , 813–825.

Englich, B. , & Mussweiler, T. (2001). Sentencing under uncertainty: Anchoring effects in the courtroom. Applied Social Psychology , 31 , 1535–1551.

ForsterLee, L., Kent, L. , & Horowitz, I. A. (2005). The cognitive effects of jury aids on decision-making in complex civil litigation. Applied Cognitive Psychology , 19 , 867–884.

Guthrie, C., Rachlinski, J. J. , & Wistrich, A. J. (2001). Inside the judicial mind. Cornell Law Review , 86 , 777–830.

Hannaford-Agor, P. L., Hans, V. P., Mott, N. L., & Munsterman, G. T. (2002). Are hung juries a problem? Retrieved from The National Center for State Courts: www.ncsconline.org/WC/Publications/ Res_Juries_HungJuriesProblemPub.pdf.

Hastie, R. (ED.) (1993). Inside the juror: The psychology of juror decision making . New York: Cambridge University Press.

Hastie, R., Penrod, S. D. , & Pennington, N. (1983). Inside the jury . Cambridge, MA: Harvard University Press.

Hertel, G., Neuhof, J., Theuer, T. , & Kerr, N. L. (2000). Mood effects on cooperation in small groups: Does positive mood simply lead to more cooperation? Cognition & Emotion , 14 , 441–472.

Johnson v. Louisiana , 406 U. S. 356 (1972).

Kalven, H. , & Zeisel, H. (1966). The American jury . Chicago: University of Chicago Press.

Kaplan, M. F. , & Miller, L. E. (1987). Group decision making and normative versus informational influence: Effects of type of issue and assigned decision rule. Journal of Personality & Social Psychology , 53 , 306–313.

Kerwin, J. , & Shaffer, D. R. (1994). Mock jurors versus mock juries: The role of deliberations in reactions to inadmissible testimony. Personality & Social Psychology Bulletin , 20 , 153–162.

Knoblich, G. , & Jordan, J. S. (2003). Action coordination in groups and individuals: Learning anticipatory control. Journal of Experimental Psychology: Learning, Memory, & Cognition , 29 , 1006–1016.

Loftus, E. F. (1975). Leading questions and the eyewitness report. Cognitive Psychology , 7 , 560–572.

MacCoun, R. , & Kerr, N. L. (1988). Asymmetric influence in mock jury deliberation: Jurors’ bias for leniency. Journal of Personality & Social Psychology , 54 , 21–33.

Maki, R. H., Weigold, A. , & Arellano, A. (2008). False memory for associated word lists in individuals and collaborating groups. Memory & Cognition , 36 , 598–603.

Nemeth, C. (1977). Interactions between jurors as a function of majority vs. unanimity decision rules. Journal of Applied Social Psychology , 7 , 38–56.

Ohtsubo, Y. (2005). Should information be redundantly distributed among group members? Effective use of group memory in collaborative problem solving. Applied Cognitive Psychology , 19 , 1219–1233.

Pritchard, M. , & Keenan, J. (2002). Does jury deliberation really improve jurors’ memories? Applied Cognitive Psychology , 16 , 589–601.

Reimer, T. , & Katsikopoulos, K. V. (2004). The use of recognition in group decision-making. Cognitive Science , 28 , 1009–1029.

Reysen, M. B. (2003). The effects of social pressure on group recall. Memory & Cognition , 31 , 1163–1168.

Ruva, C., McEvoy, C. , & Bryant, J. B. (2007). Effects of pre-trial publicity and jury deliberation on juror bias and source memory errors. Applied Cognitive Psychology , 21 , 45–67.

Saks, M. J. (1977). Jury verdicts: The role of group size and social decision rule . Lexington, MA: Lexington Books.

Salerno, J. M. , & McCauley, M. R. (2009). Mock jurors’ judgments about opposing scientific experts: Do cross-examination, deliberation, and need for cognition matter? American Journal of Forensic Psychology , 27 , 37–60.

Sandys, M. , & Dillehay, R. C. (1995). First-ballot votes, predeliberation dispositions, and final verdicts in jury trials. Law & Human Behavior , 19 , 175–195.

Schkade, D., Sunstein, C. R. , & Kahneman, D. (2000). Deliberating about dollars: The severity shift. Columbia Law Review , 100 , 1139–1175.

S.E.C. v. Koenig, 557 F. 3d 736 (7th Cir. 2009).

Spanos, N. P., Dubreuil, S. C. , & Gwynn, M. I. (1991). The effects of expert testimony concerning rape on the verdicts and beliefs of mock jurors. Imagination, Cognition & Personality , 11 , 37–51.

Spellman, B. A. , & Tenney, E. R. (2010). Credible testimony in and out of court. Psychonomic Bulletin & Review , 17 , 168–173.

Tenney, E. R., MacCoun, R. J., Spellman, B. A. , & Hastie, R. (2007). Calibration trumps confidence as a basis for witness credibility. Psychological Science , 18 , 46–50.

Article   PubMed   Google Scholar  

Thorley, C. , & Dewhurst, S. A. (2007). Collaborative false recall in the DRM procedure: Effects of group size and group pressure. European Journal of Cognitive Psychology , 19 , 867–881.

Thorley, C. , & Dewhurst, S. A. (2009). False and veridical collaborative recognition. Memory , 17 , 17–25.

Walther, E., Bless, H., Strack, F., Rackstraw, P., Wagner, D. , & Werth, L. (2002). Conformity effects in memory as a function of group size, dissenters, and uncertainty. Applied Cognitive Psychology , 16 , 793–810.

Weldon, M. S., Blair, C. , & Huebsch, P. D. (2000). Group remembering: Does social loafing underlie collaborative inhibition? Journal of Experimental Psychology: Learning, Memory, & Cognition , 26 , 1568–1577.

Wheatmann, S. R. , & Shaffer, D. R. (2001). On finding for defendants who plead insanity: The crucial impact of dispositional instructions and opportunity to deliberate. Law & Human Behavior , 25 , 167–183.

Willoughby, T., Wood, E., McDermott, C. , & McLaren, J. (2000). Enhancing learning through strategy instruction and group interaction: Is active generation of elaborations critical? Applied Cognitive Psychology , 14 , 19–30.

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Salerno, J.M., Diamond, S.S. The promise of a cognitive perspective on jury deliberation. Psychonomic Bulletin & Review 17 , 174–179 (2010). https://doi.org/10.3758/PBR.17.2.174

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Received : 03 July 2009

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Issue Date : April 2010

DOI : https://doi.org/10.3758/PBR.17.2.174

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Cognitive and human factors in legal layperson decision making: Sources of bias in juror decision making

Lee j. curley.

1 Faculty of Arts and Social Sciences, School of Psychology and Counselling, the Open University, Milton Keynes, UK

James Munro

Itiel e. dror.

2 UCL JDI Centre for the Forensic Sciences, University College London, London, UK

Juries in adversarial courts are tasked with several responsibilities. They are asked to: 1) assess the credibility and reliability of the evidence presented; 2) deliberate; 3) and then reach a decision. Jurors are expected to evaluate said evidence in a rational/impartial manner, thus allowing the defendant their right to a fair trial. However, psychological research has shown that jurors are not rational and can reach inaccurate decisions by being biased by certain factors. The aim of the current review was to explore the potential sources from which biases are introduced into the jury. Three main sources of bias were focussed upon: 1) pre-trial bias; 2) cognitive bias; 3) bias from external legal actors (expert witnesses). Legal scholars commonly cite deliberations as a method of attenuating individual juror bias, this claim is evaluated in the review. The review concludes that bias is a multifaceted phenomenon introduced from many different elements, and that several sources of bias may interact with one another during a jury trial to cause the effects of bias to snowball. Four recommendations are made: 1) juror selection should be utilised to create heterogenous juries that challenge problematic biases from individual jurors; 2) increase the quality of expert testimony through training; 3) procedures such as Linear Sequential Unmasking should be adopted by expert witnesses to filter out some sources of bias; 4) legal professionals and jurors should be educated about the effects that biases may have on decision making; 5) more research into bias in jurors is needed.

Introduction

Jurors are legal laypersons who are expected to hear evidence, and then evaluate its credibility and reliability, to reach a verdict in a fair and impartial manner (i.e. non-biased. 1 ) Defendants are entitled to a fair trial and any influence from bias undermines the jury process. Despite this, a whole range of biases exist that influence jurors when they reach verdicts. 4 , 5 Bias here has been defined as a factor that produces a preference towards a certain outcome (acquittal or a conviction). 2 The ramifications of biased and unfair decision-making by jurors can result in injustice. For example, in the case of Sajid Qureshi, he was incarcerated for four years by a jury, where several jurors acknowledged that they had made up their minds before hearing the evidence, 6 thus highlighting that bias can influence the judgments of jurors.

There are a whole range of opportunities where bias can be introduced into jurors’ decisions. Previous research has highlighted that bias may be introduced by many factors, such as: 1) pre- trial beliefs and attitudes; 2) cognitive bias; and, 3) biased interpretations of evidence by expert witnesses. 7 Through said factors, bias may play a role in deliberations and may (or may not) impact the decision outcome.

One reason for having a multiple-person jury is that individual biases are intended to be “averaged out”. 11 However, for this to reasonably occur, a few conditions and assumptions would need to be met. For example, several biases would need to be equally spread out across the jury. If a bias that black people are more likely to commit crime is present in the jury, then there would also need to be a bias that white people are more likely to commit crime, or at least, that black people are no more likely to commit a crime in the jury. These many assumptions and conditions are unlikely. Indeed, proxy research (there is very limited access to actual jury deliberation) on jury decision making suggests the intended ‘averaging’ does not occur. 12 It should be mentioned here that research on jury deliberations is limited due to a number of factors, including, but not limited to, cost, time constraints, that it is difficult to organize 12 participants to be in same location at once and that researchers do not have access to real world trials or deliberations. 13 , 14

The purpose of the current review, therefore, is to highlight and organize the potential sources of bias in juror decision making. To do this, research focusing on three main stages of a trial will be evaluated: 1) pre-evidence presentation (pre-trial publicity); 2) during evidence presentation (cognitive bias and bias from experts) and 3) post-evidence presentation (i.e. during deliberations). The paper will then make recommendations that can reduce the potential for bias and suggest further research into the various ways to combat bias.

Before introducing the literature, it is important to note, that the focus of the current review is on the jury systems in England and Wales, Northern Ireland and Scotland (although Scottish specific issues such as the not proven verdict, will not be discussed here). Despite this focus, some of the research may have been conducted in other countries, such as the United States of America. Therefore, only universal factors that are likely to influence jurors in the jurisdictions mentioned above (pre-trial bias) will be discussed.

Pre-evidence presentation

Pre-trial bias.

Pre-trial biases and attitudes are among a number of individual differences that influence the verdicts reached by jurors. For example, in addition to bias, personality and political persuasion, can impact juror’s decisions. 2 , 9 , 15 , 16 The current review will focus on bias and attitudes, however, as the vast majority of the literature has focused on the effects of more global attitudes and how they bias jurors rather than specific political persuasions and/or personality traits.

One early attempt of measuring the influence that pre-trial biases have on verdict choice comes from the Juror Bias Scale (JBS). 17 The JBS is a 17-item questionnaire that consists of two constructs: 1) the probability of commission; and, 2) reasonable doubt. The probability of commission construct measures prior beliefs and attitudes surrounding evidence. It reflects the extent to which an individual believes that accused people committed the crimes they are accused of. It highlights how guilty the juror may perceive the defendant to be . Nine items were found to adequately measure the probability of commission construct. An example of question relating to the construct include: “defense lawyers don't really care about guilt or innocence, they are just in business to make money”. 18 Again, the probability of commission construct taps into attitudes relating to a conviction bias, where jurors believe that accused individuals are likely to be guilty, with higher scores indicating a bias towards the prosecution.

The reasonable doubt construct, which is constructed through eight- items, measures how certain the juror needs to be before convicting. 17 For example, one item in this construct is: “For serious crimes like murder, a defendant should be found guilty so long as there is a 90% chance that he committed the crime”. 18 Scores on the JBS (from both constructs) can vary from 17 to 85, with high scores indicating a prosecution bias, and low scores highlighting a defence bias. Lecci and Myers 9 found that the scale accounted for 11.6% of the variance in pre-deliberation verdicts and 6.1% of the variance in post-deliberation verdicts; for more information on analysis, please see Lecci and Myers. 9 This means that the degree of bias shown by the juror has a notable influence on the verdict they give.

Since the juror bias scale was developed, further research has measured the effects of a number of pre-trial biases and their impact on the decision making of jurors. Lecci and Myers 9 , 19 developed the Pre-Trial Juror Attitude Questionnaire (PJAQ), which is made up of six separate constructs or biases: 1) conviction proneness; 2) system confidence; 3) cynicism towards the defence; 4) social justice; 5) racial bias; 6) innate criminality (p. 623). Lecci and Myers 9 found through the PJAQ that pre-trial biases can be used to predict verdict tendencies. For instance, the PJAQ predicted 21% and 15.1% of the variance in verdict choice at both the pre-deliberation and post-deliberation stage respectively.

Although, all types of bias are not equal, with some of the above constructs having stronger relationships with juror outcomes when compared to others. 9 For example, conviction proneness ( r  = .39) had a stronger relationship with the pre-deliberation verdicts than other constructs such as system confidence ( r  = .34), social justice ( r  = .15) and innate criminality ( r  = .16) 9 Interesting, some constructs, such as cynicism towards the defence ( r  = .12) and racial bias ( r  = .06), had no significant association with pre-deliberation outcomes; the role of the latter may have been attenuated due to race not being salient in the mock crime. 9 Therefore, certain biases may play more of a role in juror decision making than others.

Recent research has utilised the PJAQ when investigating the effects that pre-trial biases have on juror verdicts. For instance, Lundrigan et al. 2 aimed to investigate if the effect of pre- trial biases on verdict tendencies were mediated by juror interpretations of ‘ beyond reasonable doubt ’. First they found that the PJAQ, on its own, could explain 18.2% of the variance in verdicts that were given by individual jurors, and that by combining the PJAQ with the JBS and the Revised Legal Attitudes Questionnaire (RLAQ-23; a measure of legal authoritarianism) 21.2% of the verdict variance could be explained. Second, it was found that interpretations of ‘ beyond reasonable doubt’ significantly predicted the verdicts ultimately given by jurors. Third, it was found that the PJAQ was a significant predictor of ‘ beyond reasonable doubt’ interpretations, with jurors who are more prone to conviction than acquittal having a lower standard of proof required before they are ready to convict. When ‘ beyond reasonable doubt’ interpretations were controlled for, the predictive ability of the PJAQ over verdict tendencies decreased, but remained significant. These finding suggest that juror interpretations of ‘ beyond reasonable doubt ’ may act as a partial mediator between pre-trial biases and attitudes and the verdict that is ultimately given.

Bias can also enter the courtroom from the presence of pre-trial publicity. Pre-trial publicity was once a type of biasing information that would only influence high profile cases and celebrity trials. However, in the current digital age, jurors could be infected with biasing information regarding any defendant through information that is shared on the internet or on social media sites; a type of viral bias. 20 Further, Pre-trial publicity has consistently been shown to bias juror judgements in mock trials. 9 , 19

In summary, pre-trial biases appear to effect verdict outcome in jury decision making. Although some of the effects of pre-trial bias may be small, bias has a tendency to snowball as it interacts with other elements of a decision. 8

During evidence presentation

Cognitive bias.

Cognitive bias is a hypernym that can be utilised to describe the subjective perceptions of individuals which may influence the decisions they make and how they interact with the world. 21 Further, cognitive bias is produced by: 1) Homo Sapiens having a limited cognitive capacity and thus striving for efficiency when making decisions; and 2) personal and subjectively perceived experiences gained from the environment. 24 Our cognitive capacity is spared through the use of cognitive short-cuts, such as heuristics. Although mostly useful, heuristics, and their associated biases, can sometimes lead to errors in judgements. 25 The phenomenon of cognitive bias has been studied in a plethora of different applied environments (e.g. forensic, legal, medicine, and financial) and it has been shown that laypersons, as well as experts, are not immune to the effects of cognitive bias. 8 , 24 , 28

In a landmark study by Carlson and Russo, 7 the effects that cognitive bias (specifically pre-decisional distortion) has on jurors was investigated. Pre-decisional distortion was defined as: “jurors’ biased interpretation of new evidence to support whichever verdict is tentatively favored as a trial progresses.” (P.91). Carlson and Russo 7 found in two separate studies (the first with a student sample, and the second with a sample of individuals who were selected for jury duty) that jurors tended to favour a verdict before all the evidence was presented. This pre-decisional preference towards a verdict caused jurors to distort how they interpreted the subsequent evidence that was presented, meaning that they perceived the evidence to favour the verdict that was currently leading.

Pre-decisional distortion and “confirmation” bias can also be triggered by the sorts of pre-trial biases and pre- trial information, discussed earlier. For instance, jurors in a negative pre-trial publicity condition (in regards to the defendant), in comparison to control participants, had a preference towards the prosecution (making the guilty verdict their leading verdict). 32 This preference caused them to distort the evidence to support the prosecution. Jurors in the negative pre-trial publicity condition were also statistically more likely to give guilty verdicts than jurors in the control condition. Similarly, De La Fuente, De La Fuente, and García 33 found that pre-trial bias influenced jurors when evidence was ambiguous but not when the evidence favoured the prosecution. This is because when evidence is ambiguous it is easier for jurors to distort their interpretation of the evidence to favour their own preferences. Jury trials are inherently ambiguous, as police investigations with strong evidence are likely to lead to confessions of guilt and police investigations with weak evidence against a suspect are unlikely to reach the courtroom. 28 Further, the adversarial system leads to trials being ambiguous, 34 with two opposing sides competing to convince jurors that their version of events is closer to the truth than the other side’s. The ambiguity of jury trials creates the perfect environment for cognitive bias to thrive.

The elaboration likelihood model 35 may explain why bias may play a larger role when the evidence is ambiguous. In this model, its suggests that when the environment leads to a high elaboration likelihood (that is when the environment is not cognitively taxing), individuals are much more likely to be motivated to use cognitive resources in order to engage in the debate and attend to relevant information, thus allowing them to make a decision based on the evidence. 35 However, when the environment (through little prior knowledge relating to the decision domain or a lack of interest regarding the consequences) leads to a low elaboration likelihood, decision makers are much more likely to reserve cognition through superficially processing the information or relying on prior attitudes or beliefs (i.e. potential biases) when making the decision. 35 Therefore, in ambiguous environments, jurors, who are not legal experts, may be overwhelmed by the legal terminology being directed at them and confused due to adversarial system of the courtroom. This cognitively taxing environment may cause jurors to have a low elaboration likelihood and thus utilise bias when reaching their verdict.

Cognitive processes and pre-trial attitudes also interact with defendant and victim characteristics to further amplify the effects that bias has in the courtroom. For instance, the representativeness heuristic causes decision makers to equate the similarity between a description and a possible outcome with the likelihood of that particular outcome being correct. 27 In other words, the more the decision description is able to explain an outcome, the higher the likelihood by which the decision makers judge an outcome to be the correct one, which then leads decision makers to ignore base rate statistics and be subjected to the representativeness bias (i.e. stereotyping. 27 ) Therefore, the frugal cue usage of the representativeness heuristic, combined with previous knowledge (e.g. pre-trial bias or attitude) regarding stereotypical actions of out-groups can lead to biased and erroneous decision making. That can then lead to injustices when applied to juror decision making. 36 , 37

Previous research has also shown that the interaction between cognitive bias and defendant/victim characteristics can have a negative impact on juror decision making outcomes. For example, ethnic minority groups that are commonly associated in the media with crime are also more likely to be given guilty verdicts in mock juror studies. 38 Indeed, in a meta-analysis on racial bias on verdict decisions in mock jury studies, Mitchell et al. 38 examined 34 studies with 7397 participants. A small but reliable racial bias effect was identified, which was stronger if there was a continuous scale rather than a dichotomous choice (e.g. guilty/not-guilty) and if there were no judicial instructions provided. Therefore, pre-trial biases, such as racial biases, are likely to influence how jurors’ stereotype various ethnic minorities, such biases will then influence how novel information is interpreted, and consequently, the final verdict that is given by jurors.

Bias originating from expert witnesses

Expert testimony is the process by which an expert assists a jury in understanding the evidence presented to them. Jurors must evaluate the testimony of experts in order to make a decision. 39 Criminal cases often involve multiple experts on both side of the adversarial system. 40 Experts are selected differently in various legal systems and jurisdictions, but are generally required to evidence their relevant expertise and be able to communicate that expertise in a courtroom situation. They are typically a member of a relevant regulatory body. 41

Expert testimony has a major influence on juror perception of evidence strength, but this influence is impacted on by many additional factors. These include but are not limited to: the type and complexity of evidence they are giving testimony on (e.g. eyewitness, footwear, DNA; 42 ) the type of expertise they are communicating (e.g. clinical or actuarial; 43 ) the characteristics of the expert (e.g. gender, appearance, attractiveness; 39 ) the conditions of their testimony (e.g. pay rate, frequency of testimony; 44 ) their manner of presenting (e.g. categorical like high/low, or likelihood ratios and numerical expressions; 45 ) and their willingness/ability to testify about their own doubts and biases. 46 In this section, when discussing expert testimony, we will be specifically relating to forensic scientists, but this section is likely to generalise to other areas of expert testimony.

The influence that expert witnesses have on jurors is not always positive (i.e. lead to fairer and more accurate decisions), as expert witnesses are unlikely to be rational and impartial decision makers themselves. Previous research has highlighted that task-irrelevant contextual information influences judgements across a number of forensic domains (e.g. fingerprint examination and DNA mixture interpretation. 29 ) The effects of biasing information on forensic science judgments has traditionally been seen as negative, 47 but may lead to accurate decisions in particular scenarios. 48 Nevertheless, the utilisation of task- irrelevant contextual information by forensic scientists does cause issues at the jury level, and can lead to a snowballing effect of bias in the criminal justice system, thus creating a paradox in logic. 49 For instance, in accordance with Bayesian norms, jurors should integrate separate pieces of information (e.g. a confession and DNA evidence) independently of one another. 49 If jurors correctly do this, and the forensic scientist’s evaluation of the forensic evidence was aided by their knowledge of a confession, the jurors think they are integrating each piece of information separately, when in reality each piece of evidence is related; this is known as the criminalist paradox. 49 Consequently, biased perceptions of evidence by forensic scientists may lead to non-logical judgements being made by the jury.

Despite the subjectivity of forensic evidence interpretation, the mere presence of forensic evidence, such as DNA, in the court room is likely to influence the juror. Further, the presentation of DNA evidence makes cases much more likely to reach court and much more likely for a conviction to occur. 50 DNA popularity may be based on its marketing as a mechanism that produces either a correct result or no result. 51 Furthermore, the subjectivity of expert witnesses when they are evaluating forensic evidence, combined with the perceived strength of forensic science by the public, is likely to lead to the effects of bias snowballing from the expert witness to the jury, which may deny a defendant the right to a fair trial. This possibility is exacerbated by the difficulty in presenting forensic evidence in a manner which does not further influence jury decision making. 52

Another avenue where bias can enter from expert witnesses relates to instruction bias. Expert witnesses are commonly employed by either the prosecution or defence, and work closely with the side that employs them. 53 It has been suggested that this may make expert witnesses non-neutral and influence the testimony they give, which may then snowball and influence jurors. Further, Murrie, Boccaccini, Guarnera, and Rufino 54 found that when forensic psychologist and psychiatrists were deceived into thinking they were consulting for the defence or the prosecution that their risk assessment scores significantly differed, with higher scores being given to consultants for the prosecution when compared to consultants for the defence. This problem is not unique to expert witnesses and/or forensic scientists, as police officers and eyewitnesses are as equally likely to impact jurors with their own biased interpretations of events. 55

Post-evidence presentation

Legal scholars commonly cite jury deliberations as an important factor that helps to attenuate the effects of bias in the criminal justice system. 34 , 56 The logic behind this argument is that by randomly selecting a group (usually 12; but 15 in Scotland 57 ) of jurors from the general public, a number of jurors with various biases and beliefs will be selected and that these biases will cancel each other out. 11 , 44 It has also been suggested that deliberations allow jurors to focus more on the “facts” of the case rather than on assumptions and will allow more extreme positions to be scrutinised by the collective. 44

Some research does support the claim that jury deliberations help to attenuate the effects of bias. For instance, Taylor 58 found in a mock murder trial that negative pre-trial publicity influenced individual juror judgements, with more guilty verdicts being given in the negative pre-trial publicity condition in comparison to the other three conditions (no pre-trial publicity, neutral pre-trial publicity and positive pre-trial publicity). However, the biasing effects of pre- trial publicity were reduced by jurors participating a jury deliberation, with a similar number of guilty verdicts being given across all four pre-trial publicity conditions. 58 Taylor 58 also found that the deliberation process attenuated the effects that biasing information had on jurors. Therefore, there is some evidence to suggest that deliberations may help the courts to mitigate bias in jurors. 58

However, there are two major research areas that have produced evidence that counters the claim that juries (or groups) are more rational (i.e. less biased) than individuals: 1) classical psychological research on group decision making; and 2) jury decision making research. Each of these points will be addressed in turn. First, classical psychological research (e.g. groupthink and group polarization) highlights that group decision making can lead to poor decision performance and extreme, and/or biased, positions (relative to each of the individuals) being taken. 59 , 60

Second, some previous juror research has highlighted that deliberations do not reduce the biasing effects that pre-trial publicity has on juror outcomes. For instance, a study by Ruva and Guenther 61 highlighted that jury deliberations may not attenuate the pre-trial biases that originate because of negative pre-trial publicity. Their study had two aims: 1) investigating the effects of group deliberations on bias (i.e. does it lead to a leniency bias); 2) do juries reach more extreme positions when compared to jurors (i.e. group polarisation). They found that jurors who were not exposed to the negative pre-trial publicity were more likely to favour acquittal verdicts post-deliberations (i.e. participate in a leniency bias). However, jurors who deliberated and had been exposed to the negative pre-trial publicity were worse at source monitoring (e.g. jurors were more likely to misattribute negative pre-trial publicity as forming part of the trial information). Deliberations were also shown not to influence measures of guilt when negative pre-trial publicity had been presented to jurors. 61 Consequently, group deliberations were found to introduce source monitoring errors and did not decrease the effects of biasing information.

However, it is much more likely that some individual jurors are more rational than a jury and vice versa. For example, we could assume that through randomly sampling jurors that a normal distribution of biases are recruited into a jury. We could also assume that the jury decision is an aggregate of the beliefs of a collective of jurors (which is an assumption as some jurors may have more influence than other. 16 ) If we made both assumptions, we would expect 50% of jurors on average to be more rational than juries and 50% of jurors on average to be less rational than juries. Therefore, juries are more rational than some jurors, but some jurors are subsequently more rational than juries.

The composition of biases with juries also seems to be an important factor to consider when evaluating the effects that deliberations have on the usage of biases in juror judgements. For instance, in a study by De La Fuente et al., 33 deliberations increased the differences between juries made up of pro-defence jurors when compared to juries made up of pro-prosecution jurors. In their study, mock jurors completed the JBS and were allocated to either pro-defence or pro-prosecution juries based on their answers to the questionnaire. The results of the study highlighted that jurors with a pro-prosecution (pro-defence) bias gave significantly more (fewer) guilty verdicts post deliberation in comparison to pre-deliberation when the evidence presented was ambiguous. Therefore, juries that are homogeneous in relation to pre- trial biases are problematic and may lead to the effects of bias being amplified within the courtroom. 33 Further, jury selection procedures that allow juries to be made up of a group of heterogeneous jurors may aid the criminal justice system in tackling bias; this topic will be addressed further in the recommendations section.

From a limited amount of access to deliberation rooms and a great deal of proxy research it can be suggested that the intended ‘averaging’ out of biases does not always occur. 11 More research that incorporates group deliberations into their designs is consequently needed for the academic community to get a fuller and more nuanced understanding of the effects that group deliberations may have on bias.

Recommendations

In relation to pre-trial bias, one method of attenuating bias would be for courtrooms to utilise jury selection (or Voir Dire) procedures based upon scientific instruments such as the PJAQ. 2 , 9 , 33 The PJAQ, and similar inventories that measure bias, would allow courtrooms to screen out jurors with extreme views or perceptions, 62 which may be particularly important in relation to rape trials. By filtering jurors with a preference for a particular verdict (guilty or not guilty) out of a jury, there would be less of a tendency for pre- trial biases to guide evidence evaluation in trials, thus limiting the effects that these biases may have on the final verdict choices of jurors. 2 , 9 , 33 However, caution must be taken in any filtration and selection of jurors, as this can be easily misused (intentionally or not).

Obviously, there are practical issues in regards to implanting such a strategy. Some biases may not influence certain trial types, for example an individual who beliefs in rape myths may still be perfectly capable of serving as a juror in homicide trial. The decision to remove certain jurors will depend on the complex interplay between the characteristics of the crime, the defendant, the evidence presented and the juror (alongside the attitudes and experiences they bring). More research is needed in this area to establish how pre-trial biases interact with the factors above in order to inform how tools such as PJAQ can be used for jury selection. Another issue is, whose role would it be to make decisions regarding jury selection? Would it be legal professionals? This may not attenuate bias to the courtroom but instead could just add a new avenue for bias to enter trials. Further, these individuals may not have the expertise and are already stretched due to workload demands. We instead suggest that psychologists, who have expertise in using tools such as PJAQ be employed to select jurors. However, before said changes were made, it would be advisable to conduct research to assess the effectiveness of such a change and to consult legal professionals on their perceptions to said recommendation.

Cognitive bias, however, has proven more difficult to deal with. This is because cognitive bias is produced by natural cognitive structures (such as schemas and heuristics) and are consequently an artefact of thinking and reasoning. 25 , 27 Therefore, it is impossible to remove cognitive bias entirely from the juror decision process. The effects of cognitive bias have been shown to be attenuated by the presentation of strong evidence. 30 , 34 Nevertheless, as previously mentioned, trials in the adversarial system are inherently ambiguous, 28 leaving the potential for bias to always have an impact on juror decisions. 62

One way of tackling cognitive bias, however, may be to improve the quality of the evidence presented to jurors from expert witnesses. Expert testimony could be improved through a number of different strategies: 1) increased training to help experts communicate their testimony in a clear and logical way that legal laypersons understand; 2) using independent experts that are not associated with either side of the adversarial process; 8 3) improving codes of conduct for expert witnesses 63 Again, mock jury research should be conducted to assess the effectiveness of these approaches in reducing the effects of bias in the courtroom.

More research is needed which tackles the effects that jury deliberations have on bias. Nevertheless, the stratified sampling of jurors through instruments, such as PJAQ, may also help to decrease the chances that juries with extreme homogenous biases (i.e. juries consisting of pro-prosecution or pro-defence jurors) will be selected. 35 Meaning that juries could be composed, through a selection procedure, of heterogeneous jurors. This may allow jury deliberations to be more fit for purpose and act as method of attenuating the effects of bias in jurors (as jurors will be critiquing, rather than confirming, each other’s beliefs). Also, how jurors deliberate can be structured in a way that enhances the benefits of group decisions, while minimizing negative group dynamics.

Another method of attenuating the effects of bias in jurors would be to remove biased testimony (surrounding events and evidence) from the courtroom. We propose that the ‘war against bias’ should also be fought where evidence is collected, interpreted, and presented by forensic scientists; as this may reduce the effects of negative biases snowballing throughout the legal system. We suggest three fronts. First, the study of forensic bias needs to investigate the effects of non-relevant contextual information on forensic scientists in ecologically valid settings and utilise commonly used principals of experimental study (e.g. randomisation procedures. 64 ) Further, previous studies on contextual bias in forensic examiners has not included control groups, analysed data using inferential statistics, not included information regarding randomisation procedures and/or conducted the research in artificial settings with non-practioners. 64 Research of higher quality is therefore needed in order to combat the effects of biased decision making in forensic examiners. 64 Such research will help to establish mechanisms for reducing the effects of bias in the evaluation of forensic evidence. Second, we propose that techniques, such as Linear Sequential Unmasking (LSU), are used by forensic laboratories to minimise the potential for contextual information to have a negative effect on the decision making performances of forensic scientists. 65

LSU is a procedure “ that requires examiners not only to first examine the trace evidence in isolation from the reference material, but also provides a balanced restriction on the changes that are permitted post exposure to the reference material. ” 65 (P.3). In other words, in LSU, examiners would examine the evidence at the crime scene (e.g. fingerprints) without knowledge of reference material from the accused (e.g. their fingerprints). During this period the examiner would state unique features of the trace evidence, ensuring that analysis of trace evidence is not contaminated by knowledge of the reference material. Then, examiners can analyse the reference material, any changes to their initial analysis should then be documented to ensure transparency. 65

LSU has been expanded to also minimise noise, 66 and improving decision making in general, by sequencing the task-needed information also by its level of objectivity as well as level of relevance. 67 Other techniques that could be employed are evidence line-ups, where examiners need to match up the trace material with the correct reference material, despite the presence of foil evidence. 68 However, the effects of bias on forensic examiners is likely to be multifactorial and several methods should be employed to attenuate bias at this stage of the criminal justice system in order to stop the effects of bias snowballing and impacting on juror judgements.

A third recommendation is that psychologists should educate jurors and legal professionals about the impacts of bias and task-irrelevant contextual information on the judgements of forensic scientists. 69 In relation to legal professionals, this could be conducted as part of their continuous personal development and conducted on an annual basis. For jurors, a short informative video, designed by psychologists, could be shown to jurors prior a trial. However, research should be conducted to test if such a training course would be effective at making jurors and legal professionals more aware about the impacts of bias. Further, training courses and/or informative videos could also educate jurors, and legal professionals, about the potential for information to be linked through the potentially biased evaluation of the forensic scientist (i.e. the criminalist paradox. 49 , 69 ) Through providing lawyers with said information it will give them a tool to question the objectivity of forensic scientists and thus may decrease the influence that biased forensic evidence may have on juror judgements. For instance, research has found that when expert witnesses are questioned and cross-examined about the influence of bias and task-irrelevant contextual information on their judgements, jurors perceive the expert witness as less credible and are more likely to acquit. 70

In regards to the testimony given by police officers and eyewitnesses it is unlikely that bias can be removed from their interpretation of events. For instance, the police may generate a biased perception of a suspect through finding out their fingerprints matched with the prints found on the weapon. This bias may then influence how they investigate a crime and, subsequently, what they tell the jury, which could lead to jurors generating their own biases against the defendant. Eyewitnesses’ perceptions of events may be influenced by factors preceding the criminal event. For example, a fight between two adults (each equally to blame) may be perceived as an assault by one of the adults if the beginning of the altercation is missed by the witness. In a similar vain to the above paragraph, psychologists should educate legal professionals on bias and the effects that contextual information may have on how individuals (eyewitnesses and police) may interpret events and evidence. This may allow jurors to evaluate the impact that bias has had on the witness’s interpretation of events.

Despite our critique here of bias in jurors, we are not necessarily suggesting that judges should exclusively make decisions on guilt. Research has shown that judges: 1) use heuristic decision making strategies; 2) make similar judgements to jurors; and 3) when they make different judgements to jurors, they are more likely to give a guilty verdict, which may increase incidences of injustice. 71 In addition, judges have been shown to: 4) demonstrate similar rates of implicit bias regarding race as members of the general public; 74 5) show socioeconomic biases, most prominently in child custody cases; 75 and, 6) to hold biases based on religion. 76 Previous research has also highlighted that expertise may have a paradoxical effect on bias; with experts developing schema, stereotypes and base rates that bias how they perceive the information relevant to the decision. 77 Consequently, the replacement of jurors with expert judges may not, by itself, attenuate the role that bias plays in the criminal justice system. Despite these findings, a substantial minority of legal professionals indicate a preference for panels of judges to replace juries. 57

In summary, bias enters the courtroom in a number of ways and the effects that it has on juror decision making is multi-factorial. Due to this a number of strategies, some listed above, could be employed to aid in the fight against bias. However, before recommendations can be implemented, more research is needed to assess the effectiveness of certain bias reducing strategies (both independently and when interacting with other strategies). For this, governments and legal bodies need to take the effects of bias more seriously and fund high quality jury studies aimed at tacking the effects of bias in the criminal justice system.

In conclusion, bias is a multifaced phenomenon that can be introduced to the process of juror making through a number of avenues. Previous research has highlighted that jurors may be biased by pre-trial attitudes and beliefs and cognitive processes. Further, biases may also be introduced into the courtroom through witness (both expert and non-expert) testimony that is biased. Each element discussed in this review has the potential to interact with each other and consequentially cause the effects of bias to snowball throughout the legal system. Legal scholars commonly suggest that jury deliberations are a successful method of attenuating bias in jurors. However, there is limited and contradictory evidence here. In this review, four main practical recommendations can be made to attenuate the effects of bias on jurors. First, tools such as PJAQ should be used to ensure that juries consist of a heterogenous group of jurors, each with differing beliefs and biases. Therefore, pre-trial biases in jurors may cancel each other out in the deliberation room. Second, improve the quality of expert testimony through increased training and using independent experts that are not associated with either side of the adversarial process. Third, research into the effects of contextual information on forensic decision making is continued with a greater emphasis on experimental control and ecologically valid settings, and measures such as linear sequential unmasking are utilised by forensic laboratories. Fourth, jurors and legal actors (judges/lawyers) should be provided with some knowledge relating to the effects that bias can have on witness (both expert and not) interpretations of situations and evidence. Only then can the objectivity of witnesses be assessed in the courtroom.

Declaration of conflicting interests: The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding: The authors received no financial support for the research, authorship and/or publication of this article.

ORCID iDs: Lee J. Curley https://orcid.org/0000-0001-5829-4740

James Munro https://orcid.org/0000-0003-3638-0765

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11 Neuroscience and Jury Decision-Making

• Published: September 2018
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This chapter examines the emerging use of neuroscience evidence in criminal trials and its influence on jury decision-making. It begins with a look at the prevalence of neuroscience expert evidence in criminal cases, finding a rapid increase in its use both in and outside of the United States. It then looks at the broader research on how the lay public is persuaded by neuroscience-derived information, followed by an examination of the relatively young literature on the specific (and often paradoxical) impact of neuroscience and neuroimagery on jurors’ judgments of criminal defendants. The chapter concludes with some caveats about the current state of neuroscience with respect to the legal system and some recommendations for future research.

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Jury Psychology and Decision Criticism Essay

Introduction, reference list.

A person spends most of his life in collective entities of various kinds: family, school, organization, or other institutions. Moreover, these institutions can be considered as an organized unity, structuring and, at the same time, limiting the space of human existence. Each person has universal properties that reveal their creative potential and qualities determined by their inclusion in a particular system. At the same time, some qualities secure their membership in the system, while others oppose it and contribute to going beyond its limits.

However, society has its laws and is not always focused on the interests of a particular person. As a result, there can be conflicts between society and a person. A person is born as an individual, but from the very first moments of his life, a human cub is included in the system of social relationships and processes and acquires a special quality – he becomes a person. Thus, “personality” is a category denoting a person as a carrier of specific social properties, as a product of social interactions.

Therefore, conflicts between society and the individual are a frequent phenomenon. For his part, as a separate individual, the editor may be right in being critical (Boginskaya, 2020). However, the jurors who made the decisions represent a separate society with a collective response. Moral consciousness is a deliberately assimilated and internally accepted system of principles, norms, and rules of moral activity and behavior that regulates people’s relationship to each other and society. Moral consciousness, formed mainly through moral education, is expressed in the form of moral concepts, judgments, and conclusions about conscience, shame, sin, good and evil, love and fidelity.

The main difference between a jury trial and other forms of legal proceedings is that the decision on the guilt or innocence of the defendant is made in it by a panel of non-professional judges. Among the jurors chosen, the candidates generally do not have a law degree. The distribution of responsibility between the judge and the jury for the delivered verdict is based on the following ideas. The purpose of the trial is not to fight crime or quickly and thoroughly solve crimes. It is focused not on the inevitability of responsibility and non-legal education but on a fair decision and the solution to the issue of human destiny.

In terms of applicable theories, in this case, with a jury, the theory of groupthink can be considered. Groupthink occurs when people are deeply involved in the activities of a cohesive group. In this case, members’ aspirations for unanimity outweigh their motivation to be realistic about alternative courses of action (Strathie et al., 2015). When a team functions in a groupthink mode, there is no room for discussion or alternative points of view. There will be a link to a particular point of view, and warning signs or conflicting data will be discarded. Symptoms such as self-censorship and the illusion of unanimity can be one of the main reasons for making a decision (Strathie et al., 2015). Furthermore, the illusion of invulnerability, the belief in the innate morality of the group, can put some pressure on the jury, resulting in the wrong conclusion.

The theory of pluralistic ignorance on the part of witnesses may apply to the case. The phenomenon of pluralistic ignorance is a situation in social psychology in which the majority of the members of a group reject a norm without expressing it openly (Strathie et al., 2015). However, they incorrectly assume that most of the other members of the group support her and therefore support her as well. Multiple ignorances may explain the bystander effect in emergencies and in court. If none of those present act, then the bystanders assume that others consider the intervention wrong and thus persuade themselves to refuse to help the victims. Additionally, resources provide insight into an individual’s conflict with a group of individuals, which can lead to emotional outbursts and unfair criticism.

The main theoretical position on which the psychological study of decision-making by jurors is based is the path to the study of human behavior as a process of information processing. Supporters of the cognitive approach believe that a person receives information from the external environment, which, being processed by him, serves as the basis of his actions. Under this theory, the jury decision-making process can be described as follows. Litigation is a stimulus that is processed by the jury, as a result of which they perform an act of behaviour and reach a verdict.

Separate components of this incentive are the stages of the trial, at which the jurors receive information about the main evidence, including the testimony of witnesses and physical evidence. Moreover, they hear the parting word of the judge, the opening speeches of the lawyer and the prosecutor, as well as the debate with their participation. In this regard, the psychology of jury decision-making is multifaceted and focuses on individual perceptions combined into a common decision.

Moreover, in the case of sharp criticism of the author, one can say that individuality is a relatively late product of human history. Both the development of mankind as a whole and individual development are equally responsible for the formation of the individual. Nevertheless, in both cases, in the first place, individual (biological) properties manifest themselves and make themselves felt in the form of elementary needs for maintaining life. Further, the development of a person leads to the stage at which the natural specificity is supplemented by the social one – the individual becomes a personality. However, jurors are in an artificially created society and are guided by the opinions of each other. Thus, when outweighing the majority of the captain’s innocence, the other members could natively agree with the majority.

The process of socialization of each individual can be described as an entry into the field of human culture. Their access to this world relies primarily on mastering the language and mastering the forms of contact with other people and ways of dealing with environmental objects developed by the experience of previous generations (Strathie et al. , 2015). Introduction to culture is a type of socialization in which young people absorb the culture of the society in all its diversity directly, directly through their own perception. However, the richness of culture is multifaceted, and no one can fully perceive it. Each individual is capable of mastering only some small part of the culture. Thus, it may affect the decision of jurors from different cultural backgrounds. They are guided not only by their opinion but considering the opinion of each other and the majority.

However, it is important to note that the author criticizes the finished product of the trial, not knowing all the subtleties that took place during the proceeding. He considered the situation from a personal point of view, not being able to be on a jury (Cullen and Monds, 2020). The main forms of human behavior, including submission, anarchism and a tendency to individualism, are formed during puberty. At the same time, upon reaching the age of majority in the individual, the formation of the individual-normative system of the individual is completed.

Nevertheless, it is important to emphasize that the author of the article expresses his position critically and emotionally. Theoretically, conflicts can be regarded from an emotional and rational point of view (Boginskaya, 2020). However, in a real situation, it is not always possible to conduct a gradation. Aggression often prevails in a conflict, and a persistent hostility towards each other is formed among the participants in the situation. Thus, the author violently reacts to the decision of the jury, forming the image of the enemy.

To make a decision, the jury must learn several legal rules, which they learn from the parting word of the judge. In the course of deliberations, jurors are constantly faced with the choice between ordinary and legal norms. As a rule, jurors feel obliged to comply with legal regulations. In particular, when describing the process of reaching a verdict, jurors constantly emphasize that the discussion was held by the requirements of the law and avoid mentioning its violations (Strathie et al. , 2015). Thus, they talk about how the verdict was supposed to be delivered but not about how it actually happened. Wishing to emphasize their competence, the jurors pretend to have learned the rules of law even before the discussion, avoiding talking about what they learned during the discussion. Therefore, this could become one of the motivational movements for making a decision.

The result of the desire to follow legal norms is an attempt to apply them in a particular case. If this attempt fails, as it does in many cases, the jury falls back to using the ordinary rules. Thus, juries only use the rule of law in some cases (Taylor and Tarrant, 2019). In general, it can be assumed that the main difficulty in making a verdict is related to the inability of the jury to make a decision using official rules and without referring to their life experience and everyday ideas.

Concerning the critic, it should be said that critical statements can simply relieve nervous tension. This is one of the serious mistakes of the article’s author, as he broadcasts his personal opinion to the general public. Criticism is a complex process of business relationships, and its consequences can be very diverse (Mannes et al. , 2019). In order for criticism to exist in business communication at the level of presenting useful information and to be accepted by the other side, a number of rules for constructive criticism have been developed. Compliance with these rules, although it will not completely relieve a person from the negative influence of criticism, will allow for maintaining relationships between people.

In conclusion, it should be said that the question of criticism cannot be fully resolved. However, overly active opposition to the decision of the jury is inappropriate since the conclusion is made collectively based on many factors. Moreover, jurors are directly involved in the process and are a separate society in court. Thus, they can develop common moral concepts and philosophies of decision-making. Jurors look at how closely a particular person’s behavior is related to the situation. Moreover, they note how constant it is over time and how similar it is to the behavior of other people in a similar situation. In this regard, the criticism of the author of the article can be considered biased with the lack of a clear argument about what happened.

Boginskaya, O. (2020). ‘The simplification of jury instructions: legal-lay interactions in jury trials’, ESP Today , 8(2), pp. 297-318.

Cullen, H. J. and Monds, L. A. (2020). ‘Jury simulation studies: to exclude or not to exclude participants based on a lack of comprehension of the case?’, Applied Cognitive Psychology , 34(5), pp. 1224-1233.

Mannes, S., Foster, E. E. and Maier, S. L. (2018). ‘Jury instructions: how timing, type, and defendant race impact capital sentencing decisions’, Applied Psychology in Criminal Justice , 14(2), pp. 154-170.

Strathie, A., Turner J. and Barker, M. J. (2015). Living psychology: from the every day to the extraordinary. The Open University.

Taylor, J. and Tarrant, G. (2019). ‘Trial by social media: how do you find the jury, guilty or not guilty?’, International Journal of Cyber Research and Education, 1(2), pp. 50-61.

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IvyPanda. (2023, March 13). Jury Psychology and Decision Criticism. https://ivypanda.com/essays/jury-psychology-and-decision-criticism/

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Bibliography

IvyPanda . "Jury Psychology and Decision Criticism." March 13, 2023. https://ivypanda.com/essays/jury-psychology-and-decision-criticism/.

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Opinion: Juries are subject to all kinds of biases when it comes to deciding on a trial

28 February 2022

How do juries make their decisions and how often do they get it wrong? Dr Itiel Dror explains, alongside Dr Lee John Curley & Dr James Munro (both Open University).

From CSI to Law and Order, Line of Duty and Midsomer Murders, there is huge public fascination with crime and the criminal justice system. Especially when things come to a climactic ending and jurors decide on a defendant’s fate. But how much do jurors get it wrong? Will the jury convict an innocent person, or might they free a guilty person?

Ultimately, who committed the crime is often not easy to know, and jurors have to subjectively evaluate the evidence. But finding out what goes on inside the jury room and the biases that might influence jurors themselves is of huge interest and importance.

As psychologists, we can delve into jury decision making, as it requires several different areas of psychological research (cognitive psychology, social psychology, and individual differences) to unlock the processes behind the decisions jurors reach. The aim of our recent review was to bring together different areas of psychology to identify potential sources of bias that may influence how jurors make decisions.

We identified three main sources of bias: pre-trial bias; cognitive bias and bias originating from expert witnesses.

A significant part of the research literature has highlighted that pre-trial biases can influence the judgments of jurors. In 2008 researchers developed the pre-trial juror attitude questionnaire (PJAQ).

The scale measures biases that might influence juror decision making. For example, it measures biases such as racial biases and system confidence – how much faith (or not) the juror has in the criminal justice system. Through measuring these biases, we can get an indication into how strong a bias a person may have towards either the prosecution or defence. Interestingly, the PJAQ has often been shown to predict the verdict reached by jurors, with those who have a pro-prosecution bias reaching more guilty verdicts.

Due to pre-trial bias, some jurors are unable to take part in a criminal trial with an “innocent until proven guilty” mindset, even if they try. Jurors, like most humans, are not always rational, and may struggle to process and utilise all the available information in a reasoned manner.

This tendency often leads to biased decision making that can lead to errors. For example, research from 2001 found that jurors may favour particular verdicts as a trial progresses, despite being warned against doing this by a judge.

These preferences can lead to those jurors distorting the evidence against their preferred verdict or giving more weight to the evidence that favours their preference, a phenomenon known as confirmation bias.

Jurors who enter the courtroom with a bias towards the prosecution are more likely to see the evidence from the prosecution’s perspective, and dismiss the evidence presented from the defence (and vice versa when jurors have a defence bias). So initial pre-trial biases interact with cognitive mechanisms (for example, thinking, perception, memory) to cause the effects of bias to snowball.

Another origin of bias in jurors may come from “objective” and scientific expert witnesses. Researchers such as co-author Itiel Dror have shown that expert witnesses are far from objective decision makers and that irrelevant contextual information (provided, potentially, through the police) can bias their judgments and cause errors.

The diagram below shows the factors that might influence a forensic expert’s analysis. Through presenting expert testimony, biased conclusions could end up influencing the jury.

We have made several recommendations in our review. First, we suggest a jury selection procedure, using measures like the PJAQ, where jurors with prejudicial biases are weeded out from the jury pool.

Second, such procedures could also be used to create a jury with a representative pool of biases. As fallible beings, humans are likely to always have some form of bias. If the most negative of biases, such as racial biases, are removed from the jury pool, other biases could be counteracted through a mix of jurors with different beliefs and biases – for example people with confidence in the criminal justice system vs. people with little faith in the system deliberating with one another – deliberating with one another. More research is needed though, as very little has been conducted on jury deliberations.

A third suggestion is for the criminal justice system to tackle bias by protecting forensic experts from undue influences, so that powerful but biased expert evidence does not influence the jury. For example, an expert’s testimony may be biased if they knew about another piece of unrelated evidence, such as a confession, during analysis.

Methods of counteracting bias in forensic examiners include using expert witnesses not associated with either side of the adversarial system, and for labs to use techniques such as Linear Sequential Unmasking (LSU).

LSU is a technique where forensic experts analyse the information in a specific sequence in isolation from any other reference material. So, for example, first they would analyse the evidence at the crime scene such as fingerprints. But they would not have access at this point to any material pertaining to the “target” suspect, such as their fingerprints. The reference material would then be analysed and later compared to the evidence gathered. LSU ensures sequencing of the relevant contextual information so that the more objective and less biasing information is prioritised.

Bias is a significant issue in the criminal justice system and can lead to miscarriages of justice. Through researching the sources and effects, psychologists can aid the criminal justice system by helping those involved establish procedures that avoid the potential for bias to influence the process.

This article was first published in The Conversation on 28 th February 2022.

• Original article in The Conversation
• Dr Itiel Dror’s academic profile
• UCL Security & Crime Science
• UCL Engineering Science

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