G543 Forensic Psychology

This will include notes from  Reaching a verdict, making a case and turning to crime. It will include aim, method, procedure, sample, results, conclusions and evaluation.


Reaching a verdict, persuading a jury - Story orde

Aim: To find out if story order evidence summaries true causes of the final verdict + extent to which story order effects confidence in these verdicts

Method - Lab experiment

Sample - 130 Students from Northwestern Uni and Chicago

Procedure  - Listented to stimulus trial + answered questions on verdict + confidence

Results - Story order had greatest confidence in defence and prosecution. Witness order was least effective.

Conclusion: Story order has a persuasive effect.

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Reaching a verdict, Persuading a jury - Expert wit

Aim: To find out if hearing psychological research by an expert witness about eyewitness accuracy would affect a jury's descision.

Method - Lab experiment with videotaped mock trial

Sample - 538 psychology undergrads

Procedure - Watched video taped mock trial of expert witness talking about good Witness identification conditions, confience, statistics of identification and personal opinion. Questionnaire afterwards.

Results - Memory was fine - 85% recalled the testimony.  When WIC were good, more guilty verdicts and this increased if expert witness gave a descriptive testimony. Jury had more confidence in accuracy of eyewitness in good WIC, if the witness was more confident and if they heard expert witness.

Conclusion: Improved jurors knowledge and sensitivity to prevent miscarriages of justice. Shows effect of expert witness.

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Reaching a verdict, Persuading a Jury - Inadmissib

Aim: Look at effect of prior convictions, judges legal explanations and how credibility of witness affects ability to ignore inadmissible evidence.

Sample: 236 Bali state psychology students

Method: Lab experiment using mock trial

Procedure: Listened to audiotape then a questionnaire about guilt, verdict and effect of prior conviction. They then gave rating of credibility.

Results: Those who heard evidence ruled inadmissible without explanation could ignore, whereas those who were given explanation were less likely to find defendant guilty and couldn't disregard it. No evidence about credibility affectinng ability to disregard. No effect of prior conviction.

Conclusions: Calling attention makes it more important, could cause backfire effect due to sense of fair play.

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Reaching a verict, Witness Appeal - Attractiveness

Aim: To see if attractive defendants will be less guilty and vice versa.

Method: Lab experiment with a mock trial, independant measures

Sample: 71 Male and 74 female psychology students at East Carolina Uni.

Procedure: Shown pictures and given case, asked 'do you think mr radford is guilty of sexual harassment' and had to rate defendant and victim on bipolar scales such as dull-exciting, warm-cold.

Results: Physically attractive defendants and victims were rated positively on other personality variables. Attractive defendants were found guilty 56% of the time compared to unattractive at 76%. Attractive Victims made guilty verdict 77% of time compared to 55% for unattractive. Both sexes equally influenced by appearance.

Conclusion: Appearance has a powerful effect, defendants should dress up.

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Reaching a verdict, Witness Appeal, Witness confid

Aim: Examine several factors: mainly confidence in which jurors consider when evaluating eyewitness identification evidence.

Participants: Undergrads, eligible and experience jurors.

Method: Lab experiment, videotaped mock trial

Procedure: Shown videotaped mock trial, witness testified 80% or 100% confidence in identifcation. Warned by judge to be wary.

Results: Witness confidence was only variable to show statistical difference. 100% confidence had 67% convictions whereas 80% confidence has 60% convictions.

Conclusions: Witness confidence affects jury descison.

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Reaching a verdict, Witness appeal, Shields and vi

Aims: To see if shields and videotaped testimony increased guilty verdicts. To see if these protective devices affect credibility of either prosecution or defence.

Method: Mock trial based on court transcript with three versions: child in full view, with a screen and by videolink.

Sample: 150 male and 150 female psychology students white and middle class.

Procedure: Watched 2 hour film of case into sexual abuse. They then gave their verdicts and rated credibility of child witness and defendant.

Results: No significant differences between conditions, but more females than male found the defendant guilty (58.6% vs 38.6%). Females rated defendant less credible and victim more credible.  Second experiment showed when tape stopped after child testified, open room condition participants more likely to convict.

Conclusion: Shows that gender differences involved in child cases, but defendant not more at risk if protective devices are used.

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Reaching a verdict, Stages in decision making - Ha

Orientation period:

  • Relaxed and open discussion
  • Set agenda
  • Raise questions and explore facts
  • Different opinions arise

Open confrontation:

  • Fierce debate
  • Focus on detail
  • Explore different interpretations
  • Pressure on minority to conform
  • Support for group decision


  • Attempts to smooth over conflict
  • Tension released by humour
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Reaching a verdict, Majority Influence - Asch

Aim: Find out if people would conform when majority was wrong.

Method: Laboratory experiment

Sample: 123 American male undergrads

Procedures: Had to match a line to correct one, confederates purposely gave wrong answer on critical trials.

Results: 32% conformity (gave wrong answer). No one conformed all the time, 25% didn't conform once.

Conclusion: Shows impact of majority, but there are individual differences.

They conformed due to

  • Distortion of perception - thought they were right
  • Distortion of judgement - doubt in accuracy so yielded to majority
  • Distortion of action - Didn't want to be ridiculed so went with group
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Reaching a verdict, Minority influence, Moscovici

Aim: To compare effect of inconsistent vs consistent minority influence.

Sample: All female

Method: Laboratory experiment with confederates

Procedure: Shown slides which were clearly blue, with a confederate minority either being inconsistent in saying its green or consistent.

Results: Inconsistent minority condition made 1.25% of participants say it's green. Consistent minority condition made 8.4% participants say its green.

Conclusion: Minorities can influence majorities, especially when they are conistent. Consistent minorities appear more confident and are taken more seriously.

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Turning to crime, Cognition, Criminal Thinking pat

Aim: Understand the criminal personality and to alter traits that produce crime

Method: Interviews over several years. Freudian based therapy to find route of criminality.

Sample: 255 male from various backgrounds. Two groups: one guilty by insanity one not. High participant attrition. Only 9 changed due to therapy.

Results: Criminals are restless, dissatisfied and irritable. They consider requests at school as an imposition. They want excitement, lack empathy and are poor ar decision making.  Criminal has 52 thinking errors including need for power, perfectionism, lack of trust, poor decisions and superoptimism.

Conclusion: Personality develops over lifespan, and behaviour is due to irrational thinking process due to errors and biases in their thinking.

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Turning to crime, Cognition, Moral development, Ko

Aim: Investigate moral development, and crime as bi product.

Sample: 58 boys from chicago of working and middle class backgrounds aged 7-16.

Method: Longitudinal study

Procedure: Two hour interview with dilemas, some boys followed up at 3 yearly intervals til aged 30. Also studied in UK, Mexico, Turkey etc. One example is 'Heinz dilema' which is about stealing the drug for an ill wife.

There are 5 stages of morality and the later stages signify more moral development.

Results: Younger boys performed at earlier stages whereas older boys performed at late, suggesting evidence for development.

Conclusions: Evidence of moral development

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Turning to Crime, Cognition, Attribution of blame

Aim: Examine type of offence and attribution of blame.

Method: Used 42 item blame inventory to measure offence and blame in three dimensions: itnernal/external, mental element and guilt.

Sample: 80 criminals serving sentences in northen ireland. Sex offenders, property offenders and violent offenders. Mean ages of 28/29 and 41.

Results: Sexual offenders had most guilt, property offenders had least. Sexual offenders blamed mental the most, property the least. Violent offenders blamed external the most, sexual the least.

Conclusion: Shows strong consistency in the way offenders attribute blame across the two countries.

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Turning to crime, Biology, Brain dysfunction - Rai

Aim: Multi-factoral approach at understanding antisocial and aggressive behaviour in children with a biological basis.

Method: Review article

Procedure: Reviewed and summarised the findings of articles from neuropsychology and neurological and brain imaging studies and related it to antisocial behaviour.

Results: Low resting heart rate is a predictor of someone who will seek excitement to raise arousal. Activity in pre-frontal lobes are of a lower impulse in those who are antisocial and aggressive. Adolescent brain is still forming connections up until early 20's, this is why offending peaks here. Other issues such as birth complications, poor parenting, malnutrition and smoking and drinking during pregnancy affect likelihood of crime.

Conclusion: Early intervention may be effective to reverse effect of biological deficits.

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Turning to crime, Biology, Genes and Seratonin - B

Aim: Explain behaviour of a family in netherlands where males are affected by a syndrome which causes violent behaviour.

Sample: 5 males

Method: Data from urine over 24 hour period.

Results: Tests showed disturbed monoamine metabolism which is associated with a deficit of the enzyme monoamine oxidase A (MAOA)

In each male a point mutation was identified in the X chromosome of the gene responsible for the production of MAOA.

Conclusion: Defect in gene may lead to violent behaviour. Not all males displayed high violent behaviour even when they suffered it.

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Turning to crime, Biology, Gender, Daly and Wilson

Aim: Find out if homicide rates would vary with local life expectancy.

Method: Correlation study using survey data from police records, school records and demographic records.

Procedure: Examined chicago communites which had lower than average male life expectancies and plotted correlations.

Results: Life expectancy proved to be the best predictor of neighbourhood specific homicide rates. Neighbourhood absenteeism from school was negatively correlated with life expectancy

Conclusions: Young men expected to life shorter lives, increase risk taking for short term rewards. No point investing in school due to no future.

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Turning to crime, Upbringing, Disrupted families -

Aim: Document start, duration and end of offending behaviour. To investigate influence of life events; risk and protective factors. To investigate influence of family and intergernational transmission.

Method: Longitudinal survey, latest data gathered at 48 with interviews and criminal record searches.

Sample: 411 boys aged 8 and 9 born in 1953/54, from 6 state schools in East London. Predominantly working class. 90% interviwed again at 49.


  • at age 48, 161 had convictions
  • Offences peaked at 17
  • Those who started criminal careers at 10-13 were nearly all reconvicted once (91%) and commited 9 crimes on average compared to 6 crimes if they started at 14-16.  Most crimes commited by this group.
  • 93% Admit to commiting atleast one crime.
  • 7% chronic offenders as they commited half the crime. Most chronic offenders shared common childhood characteristics. They are persisters as they were convicted before and after 21st birthday. They were more likely to have a convicted parent, high daring, delinquent sibling, young mother, low popularityy, disruped family and a large family size. Similiar pattern for desisters.
  • Proportion of men leading successful lives was 88% at age 48.

Conclusion: Offenders are deviant in many aspects of life.  Most important risk factors are criminality in family, poverty, impulsiveness, poor child rearing and poor school performance.

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Turning to crime, Upbringing, Poverty and disadvan

Aim: To see the extent to which poverty and disadvantaged neighbourhoods were predictors of criminal behaviour.

Method: Cross sectional study with interview and data collection

Sample: 2000 year 10 students.


  • 45% males and 30% females commited at least one crime in 2000.
  • 10% males and 4% females commited serious crime.
  • High frequency offenders commit a range of different crimes
  • Offenders more likely to be victimised
  • Offenders are more drunk and use more drugs

Explanatory factors:

  • Family and social position - ethnicity, class
  • Individual characteristics - morality, dispositions, social situation, family and school problems
  • Social situation
  • Lifestyle
  • Community - bad neighbourhoods

Individual lifestyle was most important. key risk factors are weak family + school bonds, poor parenting, truancy, weak morality and weak self control.

Conclusions: Three types of adolescent offender

  • Propsensity induced - their individual characteristics, high risk factors
  • Lifestyle dependant - Depends who they hang with, what they do etc
  • Situationally limited - Good kids, situation dependant eg drugs at party
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Turning to crime, learning from others, Sunderland

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