Story Model

To better explain how jurors make decisions in trial, psychologists have proposed a variety of decision-making models. Some research has examined the decision-making process at the jury level, but the majority of research has examined juror decision-making processes at the individual level. These models are typically grouped into two categories: explanation-based models and mathematical models. The story model is the most popular explanation-based model and was developed by Nancy Pennington and Reid Hastie. The story model rests on the assumption that jurors organize evidence they hear during trial in a narrative, story-like format. According to the story model, the process of decision making takes place in three steps: story construction, learning verdict alternatives, and rendering a verdict. The story model not only describes the process the juror undergoes when making a decision in a trial but claims that the story constructed by the juror ultimately determines the verdict chosen by the juror.

Story Construction

In a typical trial, the evidence is presented to jurors in a disconnected format over several days. Not only are witnesses often not presented in a logical, temporally relevant order, but the actual content of the witnesses’ testimonies is also disconnected, in that witnesses are providing information in reaction to attorney questions rather than narrating the sequence of events. According to the story model, jurors play an active role during the trial by gathering the evidentiary information and organizing it into a comprehensive narrative with a causal structure, describing the sequence of events under question. That is, they actively place the evidence gathered at the trial into a “story” to account for what actually occurred. In constructing the story, they use three things: the evidence presented at trial (e.g., the information gained from witnesses), their personal knowledge of similar events (e.g., knowledge gained from personal experiences, media portrayals, or secondhand accounts of a particular crime), and their expectations for what makes a complete story (e.g., knowing that actions are usually preceded by intentions or goals).

In addition to describing how the jurors construct their stories, the story model describes the structure of those stories. Specifically, stories are made up of units called episodes. An episode is made up of a series of events that are paired with intentions or motivations to result in an action. Events, intentions, and motivations can be taken either from trial or from a juror’s personal knowledge. For example, an episode may consist of initiating events that led the defendant to a certain mental state, which then led the defendant to create goals or to have certain motivations, which then resulted in the defendant acting in a particular way. Jurors may get some of the information to complete the episode from trial evidence and may have to infer some of the episode elements based on their knowledge of the world. Episodes are hierarchically organized, in that each component of any given episode may be broken down into its own individual episode. The highest level episodes are the most important in explaining the actions that occurred; thus, the story model accounts for the weight jurors assign to different pieces of evidence.

One of the greatest strengths of the story model is that it accounts for jurors’ unique experiences and indicates when they add those unique experiences and pieces of knowledge into the decision-making process. Witnesses do not often have the opportunity to explain why particular events happened or how they personally reacted to a particular sequence of events. So, jurors fill in those blanks with inferences based on their own personal knowledge of similar events. In addition, jurors’ expectations about what makes a complete story are important to help them determine when important pieces of information are missing or when an inference about human behavior or how someone might act in a particular situation needs to be made. Jurors then can make this inference based on their personal knowledge. The story model accounts for differences in stories between jurors by accounting for the different world experiences and expectations jurors bring to the story construction process.

Certainty Principles

Three certainty principles govern whether a juror will find a particular story acceptable, and following acceptability, how much confidence a juror will have in a particular story. The first two—coverage and coherence—contribute to whether a story will be accepted and, if accepted, how much confidence the juror will have in the story. The third principle, uniqueness, contributes solely to the juror’s confidence in the story.

Coverage refers to the amount of evidence accounted for by a particular story. The more coverage a story has, the more likely the juror is to deem the story acceptable and, if accepted, the more confidence the juror will have in that story. Conversely, the less evidence the story accounts for, the less likely it is to be accepted by jurors. If accepted, jurors are likely to have less confidence in the story compared with if the story had a high level of coverage. If a story has low coverage and, therefore, the juror has a low amount of confidence in the story, the juror would also have a low level of confidence in the final decision based on that story.

The second principle is coherence. A story’s coherence is determined by a combination of three variables: consistency, plausibility, and completeness. To be consistent, a story must contain no internal contradictions or contradictions with pieces of evidence the juror believes are true. To be plausible, the story constructed must be similar to the juror’s knowledge of what typically happens in these situations. That is, a story must not contradict the juror’s knowledge about the world in general. Last, to be complete, the story must contain all the parts of what a juror believes makes up a story. The more consistent, plausible, and complete the story, the higher the coherence of the story. If a story is deemed coherent, the juror is more likely to think that the story is an acceptable account of the events in question and the more likely the juror is to be confident in the story.

The story model posits that jurors can construct more than one story, but one story usually emerges as the best explanation of events. However, what happens when jurors create more than one story and each of the stories is high in both coverage and coherence? According to the story model, this compromises the last certainty principle, the uniqueness of the story. If jurors construct more than one acceptable story, they are less likely to believe either story, and the confidence in both stories goes down.

Learning Verdict Options

In the second stage of the story model, jurors learn which verdict options are available to them. Generally, the different verdict options along with the definition of what constitutes each verdict option are given to the jurors in the judicial instructions at the end of the trial. The combination of this one-trial learning task with the difficulty of legal language makes this task difficult for jurors. In fact, research has demonstrated that jurors generally do not comprehend the majority of judicial instructions presented to them. In addition, jurors also have preconceived notions of what constitutes various crimes. Those preconceived notions, accurate or inaccurate, may interfere with jurors’ understandings of the verdict options in the case.

Rendering a Verdict

In this last stage of the story model, jurors map their accepted story onto each of the verdict categories to determine which verdict category best matches the accepted story. This mapping sequence is intentional on the part of jurors and is difficult because they are map-ping their accepted story onto unfamiliar, newly learned concepts. However, jurors are somewhat aided in this process by the structure of the verdict options. Typically, verdict options consist of elements that closely mimic the episodic structure that jurors used when creating the story. For example, the verdict definition of first-degree murder includes an element of identification (identifying the person who committed the crime), mental state (that person intentionally killed the victim), circumstances (the victim gave no provocation and the murder was premeditated), and actions (the killing was intentional and unlawful). These correspond to the elements that make up an episode in a story.

Once the jurors have chosen which verdict category best matches the story, jurors apply the judge’s procedural instructions to make a decision in the case. For example, in a criminal case, if the best-fit verdict option exceeds the jurors’ threshold for reasonable doubt on each of the elements of that verdict option, then the juror is likely to choose that verdict. If not, the juror does not choose that verdict option. If no match of verdict option and story exceeds this threshold, then the juror defaults to a verdict of not guilty. In addition, the goodness of fit, or the jurors’ confidence in a verdict category-story match, will affect whether the juror is likely to choose that verdict. If the goodness of fit is low, the juror is less likely to be confident in that verdict than if the goodness of fit is high.

Research Investigating the Story Model

The initial study in the development of the story model was designed to provide a picture of how jurors processed evidence and established that jurors created narrative structures to explain and account for evidence. Further research demonstrated that the actual creation of the narrative was a spontaneous act of the juror and that the story is actually a mediator in the verdict decision. That is, jurors heard the evidence, created a story, and then the story caused the jurors to choose a particular verdict. Last, the researchers also conducted a study demonstrating that the story model was a more complete and accurate explanation of juror decisions compared with more traditional models of decision making. Other researchers have also applied the story model of juror decision making to successfully explain jurors’ decisions in rape trials, civil cases, and sexual harassment cases.

In sum, the story model of juror decision making is an explanatory model of decision making that asserts that jurors actively create a narrative (in the form of multiple episodes) to organize trial evidence. In creating the story, jurors use evidence presented at trial and their own knowledge of both real-world events and the elements that make up a story. To determine whether a story is acceptable, jurors use the certainty principles of coverage and coherence. Coverage and coherence, combined with the story’s uniqueness, also contribute to the juror’s subsequent confidence in a story. The second stage of the story model is the stage in which jurors learn the verdict options available to them, and this happens during judicial instructions at the end the trial. Jurors’ preconceived notions about certain crimes may also affect the way in which they perceive the verdict categories. In the last stage, jurors map their chosen stories onto the various verdict categories and apply the standard of proof given to them by the judge. If the match exceeds the standard of proof, then the juror chooses that verdict. If not, the juror defaults to a not-guilty verdict. Last, research has generally demonstrated support for the story model of juror decision making in a variety of cases.

References:

  1. Huntley, J. E., & Costanzo, M. (2003). Sexual harassment stories: Testing a story-mediated model of juror decision-making in civil litigation. Law and Human Behavior, 27, 29-51.
  2. Olsen-Fulero, L., & Fulero, S. M. (1997). Commonsense rape judgments: An empathy-complexity theory of rape juror story making. Psychology, Public Policy, and Law, 3, 402-127.
  3. Pennington, N., & Hastie, R. (1992). Explaining the evidence: Tests of the story model for juror decision making. Journal of Personality and Social Psychology, 62,189-206.
  4. Pennington, N., & Hastie, R. (1993). The story model for juror decision making. In R. Hastie (Ed.), Inside the juror: The psychology of juror decision making (pp. 192-221). New York: Cambridge University Press.

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