New research published in the March edition of Psychology, Public Policy, and Law suggests that jurors who are exposed to color photographs of crime scenes are more likely to convict a defendant of a crime than jurors who were shown black and white photographs or merely heard descriptions of the crime scene. This research has massive implications for both criminal defense and prosecution because it helps reveal how jurors can be manipulated in the courtroom.
Jessica Salerno, a psychologist at Arizona State University, designed the study, which she conducted twice. The first time she included 193 participants, the second time, 354 participants. For the research, she created a mock trial with volunteer online jurors who evaluated information about a murder trial. The participants were split into three groups. All were given a verbal description of the victim's injuries and shown nongruesome images. Some of the jurors were then shown gruesome images in black and white, while other jurors were shown gruesome images in color.
The study revealed that the defendant was convicted of murder more often when the jury had been shown color photographs of the victim. It also showed that jurors who had been shown the color images were less affected by the strength of the defendant's argument, implying that the jurors stopped listening as carefully to reason once they were emotionally affected.
According to Salerno's analysis of the mock trial, “Color gruesome photographs consistently made jurors feel more disgusted than if they only read detailed verbal descriptions of the injuries” which “in turn made them more likely to vote guilty.”
It is important to note that the gruesome color photographs were exactly the same in every other way as the gruesome black and white photos. “Despite the color and black-and-white gruesome photographs conveying the same probative information, they only increased disgust and, in turn, convictions when they were presented in color.”
This experiment points to a well-known phenomenon for trial attorneys, that jurors can be manipulated through the presentation of specific forms of evidence. Salerno suggests that, in order to combat this fickleness, “Presenting gruesome photographs in B&W might reduce jurors' emotional reactions while maintaining their probative information.” She points out that black and white photos provide the same information without the emotional baggage.
Trial court judges are responsible for deciding whether or not a specific piece of evidence in a case is “admissible,” or if it can be shown in the courtroom during the trial to help build a case. Sometimes, judges will allow photographic or video evidence, while other times they will limit the evidence to verbal description. The judge will usually make a decision based on their perception of the importance of the evidence in comparison with its potential for prejudicial effect.
This research shows that colorful graphic images can create visceral responses in the jury which can significantly sway their view on the defendant's role in the case. As more research on the subject develops, lawyers and judges will have to decide if particularly graphic images in the courtroom are an asset to the justice system or a manipulative tactic which detracts from objective evaluation.