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Psychology in the News | Psychopathy and a Guilty Verdict

Rosey Gardiner-Earl

15th January 2024


A quick Google search of ‘TV shows about psychopaths’ yields a huge number of results, from fictional crime dramas such as ‘You’ to dramas about real-life crimes such as ‘Dahmer: Monster – The Jeffrey Dahmer Story’ (both on Netflix) it seems that mainstream media is filled with stories about individuals with the psychological disorder of psychopathy.

You have probably heard the term ‘psychopath’ but may not know exactly what it means. Contrary to representation in the media, a psychopath is not defined by violence alone (although people with psychopathic characteristics may have an increased risk of violence). Psychopathy is characterised by an extreme lack of empathy (the ability to understand or share the feelings of another). Psychopaths may also be manipulative, and charming and behave in an impulsive or risky manner (source: Royal College).

Whilst we clearly ‘love to hate’ psychopaths for our entertainment, experts in the field worry that should a jury be told that a defendant has a diagnosis of psychopathy, this could be more likely to lead to a guilty verdict, regardless of the facts of the criminal case. New research seems to suggest that this indeed could be the case.

For the study, 168 participants were given four short stories about a crime and were then asked to decide if they thought the defendant in each case was guilty, or not. Two of the stories described an assault of a man, against another man. Included in the story was a report from a psychologist. For one of the stories the defendant was described as a psychopath, for the other, no psychological difficulties were reported. The second two stories described a robbery. However, instead of a psychologist's report, they contained character references. One gave descriptions of the defendant as narcissistic, manipulative, and lacking remorse (in other words, psychopathy traits) the other described the defendant as friendly and caring.

Participants completed a questionnaire to measure their level of bias across the four stories. Results indicated that for the first two stories (assault) more participants thought that the ‘psychopath’ defendant was guilty compared to the ‘non-psychopath’ defendant. Furthermore, for the second two stories (robbery) more participants judged the defendant with the psychopathy traits to be guilty than the defendant described as friendly and caring. The reasons given for finding someone guilty, or not, were explored as part of the study. Some of the participants openly reported that the psychopathy diagnosis was one of the reasons for their decision with one reporting that ‘the defendant does not recall their actions which could be due to their psychopathy’. This, the author reports, is a clear example of a participant giving a guilty verdict due to the label of psychopathy, despite not understanding what psychopathy is and how it affects people.

Author, and clinical psychologist, Jacob van Bentum said ‘the results from this study could have major ramifications for the validity and fairness of the criminal justice system. Our results suggest that character statements, whether positive or negative, can sway a layperson’s opinion despite the fact they have no bearing on the facts of the crime. Moreover, exaggerated use of psychopathy labels could potentially lead to biased and false convictions’.

Answer the following questions

1. Explain how randomisation could have been used for the short stories presented to each participant in this study.

2. Each of the stories focused on a crime committed by a man. Why might this threaten the
external validity of this research?

3. For the defendant given the psychopathy description, there was a statistically significant
difference in the number of participants who made a guilty verdict, compared to a not guilty
verdict. The p-value was 0.007. What does this tell us about the percentage likelihood that
this result may have happened by chance?

4. The author of the paper points out the very real implications that this study might have for
the criminal justice system, what could be done to ensure that those with psychopathy still
receive a fair trial from jurors?

5. Participants were shown the stories in a controlled laboratory setting. How could this
research be made more ecologically valid?


1. Why do some people become psychopaths? Royal College (accessed 5.12.23)

2. British Psychological Society (accessed 5.12.23

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Rosey Gardiner-Earl

Rosey has 15 years of experience teaching Psychology and has worked as both a Subject and Senior Leader in school and large sixth form setting. Rosey is also an experienced A level Psychology examiner.

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