Neuroscience
As a juror in a criminal trial, you are meant to make a judgment of the defendant's guilt or innocence based on the evidence and arguments presented before you. In many trials, however, alongside the facts of the case, material and statements are allowed that don't in themselves speak to the culpability of the defendant. In a murder trial, for instance, a parent may take the stand and describe how their life has been destroyed by the loss of their child (the victim in the case). Similarly, the prosecution may present disturbing crime scene photographs of the victim, which don't say anything about the defendant's culpability, but do exert an emotional effect in the courtroom.
Writing in Psychiatry, Psychology and Law, Kayo Matsuo and Yuji Itoh at Keio University in Japan describe how they tested the effects of these kinds of evidence on the decision making of 127 students (89 women) who were asked to play the role of juror in a fictional case. The students listened to a man read out a transcript of a murder trial, in which a homeless man stood accused of murdering a young female student so that he would be sent to jail and no longer be homeless. Factually speaking the prosecution's case was weak, and while the defendant had confessed to the crime, he later recanted and pleaded innocence.
Among the students who heard a version of the trial transcript that featured no emotional testimony from the victim's father, nor any photos of the victim's body, 46 per cent of them said they thought the homeless man was guilty. Other students heard a version that did contain testimony from the victim's father, in which he expressed his grief, described how kind and bright his daughter was, and how much anger he felt toward the defendant. Although logically this testimony did not provide evidence of the defendant's guilt, 71 per cent of the students who heard the father's words said they thought the defendant was guilty, and this rose to 79 per cent if they were also shown photographs of the victim's fatally wounded body.
The effect of the father's emotional testimony appeared to be explained at least in part by the negative emotions it aroused in the students, such as anger and disgust. Among the students who rendered a guilty verdict those who heard the father's emotional testimony also tended to support a harsher sentence for the defendant – 33 per cent said he should receive the death penalty compared with just 16 per cent of those who did not hear the father's testimony. It's worth bearing in mind that the father's emotional testimony was read out to students by the narrator in a neutral voice – the psychological effects of this kind of testimony would likely be far greater in a real-life trial situation.
The researchers said their results showed that "emotional information upsets jurors and disturbs their legal decisions". They concluded that "in order to avoid false convictions and ensure a better trial system, psychological studies conducted in legal settings should explore the function of emotional evidence as well as the role of emotions."
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Matsuo, K., & Itoh, Y. (2015). Effects of Emotional Testimony and Gruesome Photographs on Mock Jurors' Decisions and Negative Emotions Psychiatry, Psychology and Law, 1-17 DOI: 10.1080/13218719.2015.1032954
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
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Neuroscience
How jurors can be misled by emotional testimony and gruesome photos
Writing in Psychiatry, Psychology and Law, Kayo Matsuo and Yuji Itoh at Keio University in Japan describe how they tested the effects of these kinds of evidence on the decision making of 127 students (89 women) who were asked to play the role of juror in a fictional case. The students listened to a man read out a transcript of a murder trial, in which a homeless man stood accused of murdering a young female student so that he would be sent to jail and no longer be homeless. Factually speaking the prosecution's case was weak, and while the defendant had confessed to the crime, he later recanted and pleaded innocence.
Among the students who heard a version of the trial transcript that featured no emotional testimony from the victim's father, nor any photos of the victim's body, 46 per cent of them said they thought the homeless man was guilty. Other students heard a version that did contain testimony from the victim's father, in which he expressed his grief, described how kind and bright his daughter was, and how much anger he felt toward the defendant. Although logically this testimony did not provide evidence of the defendant's guilt, 71 per cent of the students who heard the father's words said they thought the defendant was guilty, and this rose to 79 per cent if they were also shown photographs of the victim's fatally wounded body.
The effect of the father's emotional testimony appeared to be explained at least in part by the negative emotions it aroused in the students, such as anger and disgust. Among the students who rendered a guilty verdict those who heard the father's emotional testimony also tended to support a harsher sentence for the defendant – 33 per cent said he should receive the death penalty compared with just 16 per cent of those who did not hear the father's testimony. It's worth bearing in mind that the father's emotional testimony was read out to students by the narrator in a neutral voice – the psychological effects of this kind of testimony would likely be far greater in a real-life trial situation.
The researchers said their results showed that "emotional information upsets jurors and disturbs their legal decisions". They concluded that "in order to avoid false convictions and ensure a better trial system, psychological studies conducted in legal settings should explore the function of emotional evidence as well as the role of emotions."
_________________________________
Matsuo, K., & Itoh, Y. (2015). Effects of Emotional Testimony and Gruesome Photographs on Mock Jurors' Decisions and Negative Emotions Psychiatry, Psychology and Law, 1-17 DOI: 10.1080/13218719.2015.1032954
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
Our free fortnightly email will keep you up-to-date with all the psychology research we digest: Sign up!
- Brain Scans Could Influence Jurors More Than Other Forms Of Evidence
It's surely just a matter of time until functional MRI brain scans are admitted in US and UK courts. Companies like No Lie MRI have appeared, and there have been at least two recent attempts by lawyers in the USA to submit fMRI-based...
- Courtroom Confidence Backfires When A Witness Makes An Error
Confidence is extremely convincing – many studies have shown that both real jurors and mock jurors are more likely to believe a courtroom witness who appears confident. But what if a confident witness is seen to make an error? New research by Elizabeth...
- How To Avoid Death Row...
Whether jurors decide to hand down a life sentence or the death penalty depends in part on their perception of the defendant’s appearance. That’s the finding from interviews with 80 jurors during their involvement in real-life American murder cases....
- How Seeing A Conversation Helps People Remember What Was Said
Numerous psychology experiments have demonstrated the limitations of eyewitness memory. But less researched is ‘earwitness’ memory – how well people are able to recall criminal conversations. Now Laura Campos at the University of Granada and Maria...
- I Swear I'm Telling You The Truth
Sir Bob Geldof’s penchant for the odd swearword or two, might be a shrewder oratory strategy than we realise. Eric Rassin and Simon Van Der Heijden at Erasmus University in The Netherlands report evidence that people are more likely to rate a statement...