Forensic Psychology - Reaching a verdict

- Persuading a jury

  • Pennington & Hastie - effect of order testimony
  • Cutler - Persuasion technique
  • Pickle - Inadmissible evodence

- Witness appeal

  • Castellow - Attractiveness of defendent
  • Penrod & Cutler - Witness confidence
  • Ross - Effects of shields & videotapes (children)

 - Reaching a verdict

  • Hastie - Stages in decision making
  • Asch - Social majority influence
  • Nemeth & Watchler  - Minority influence
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  • Created by: SarahD95
  • Created on: 17-05-14 10:57

Pennington & Hastie - Effect of order of testimony

Aim: investigate the effects of story order and jurors confidence on juror verdict

Method/Design: lab exp, independent measures design

Participants: 130 £ students, Chicago uni (USA), allocated to one of 4 conditions, roughly = #

Proceudre: listened to tape recording of stimulus trial, answered questions. Reach a guilty/non guilty verdict, rate confidence on a 5 point scale. No interaction bewtween Ps. Story order - natural order, witness order - evidence arranged in closest to the original trial.
Defence items - 39 non guilty peciese of evidence, prosecution 39 guilty pieces 

Results: story order persuaded more jurors of defendent's guilt- 59% guilty verdicts to 31% in witness order (prosecution items) & 78% guilty verdicts to 63% in witness order (defence items)

Conclusion: greatest confidence in their veridct was expressed by those who heard the defence/prosecution in story order. Least confidence - the 2 witness order conditions

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Cutler - Persuasion technique

Aim: investigate whether presence of an expert witness would affect juror's decision making ability

Method/Design: lab exp, videotape mock jury of a robbery

Participants: 538 undergrads, extra cred for psych course

Procedure: ps shown videotape of trial in groups of 2-8, 4IV:
1. Witness identifying conditions  (WIC) (good/poor)
2. Witness confidence (good/poor)
3. Expert opinion expressed (high/low)
4. Form of exper testimony 

Results: juruors gave more guitly verdicts when WICs were good, increased if the psychologist used a descriptive account using ordinary language. Juror's confidence was higher in the WICs. Jurors also expressed more confidence when witness said she was 100% sure of identification.

Conclusion: expert testimony improved juror's knowledge of factors that might affected the accuracy of eyewitness testimony & make them pay more attention to the WICs

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Pickle - Inadmissible evidence

Aim: to examine how much the credibility of the witness affects the jurors ability to ignore inadmissible statements

Method/Design: lab exp, mock tiral of a fictional theft with a mock jury, ps were randomly assigned - independent measures deisgn

Participants: 236 psych students, Bali state uni (Idiana), ps took part as course requirement

Procedure: listened to adiotape of trial which contained a piece of critical evidence. 1 team was objected too by the attorney of defence team. Conditions varied at this point, some ps would hear the judge allow evidence & others would hear it disallowed. When instructed to ignore inadmissible evidence, sometimes supported with legal explanation. Judge would express that the evidence should be disregarded as it might be suggestive of bad character and bias the jury memebers. Ps completed Q asking to make several decisions aabout the case.

Results: calling attention to inadmissible evidecne, juries more likely to pay it attention & were less likely to vote for a guilty verdict, no signif effect was found if the jury knew about previous convictions. 

Conclusion: real life ap, tatic that could be used in trials to draw attention to specif evidence


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Castellow - Attractiveness of defendant

Aim: test the hypothesis - the attractive defendant is less likely to be seen as guilty & when the victim is attractive, the defendant is more likely to be found guilty

Method/Design: lab exp, mock trial independent meaures design

Participants: 71M & 74F students - extra credit for their introductory psych - East Carolina uni

Procedure: ps read a sexual harrassment case and answered Qs. Attached photos of victim & defendant (previously categorised attrac/unattractive). DV measured by answer to "Do you think Mr. Radford is guitly of sexual harassment?" Ps were then asked to rate the defendant/victim on 11 bi-polar scale, e.g dull-exciting, nervous-calm, warm-cold etc

Results: physically attractive defenddants/victims rated positively personality variables as well.
Attractive guilty verdicts = 56%, unattractive guilty verdicts = 76%
No signif gender differennces were found

Conclusion: witness attractiveness can have a powerful effect in influencing jury dedcisions 

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Penrod & Cutler - Witness confidence

Aim: identify jurors sensitivity to witness confidence & other factors

Method/Design: lab exp, videotaped trial- eyewitness identification played a key role

Participants: undergrads & eligible experienced jurors

Procedure: videotape trial robbery, witness testified she was either 80%-100% confident that she had id robber, 9 other variables all at both high & low level which were introduced into thee film, ps experienced either high/low condition variables on a random basis & were asked to decided whetehr the robber was guilty ornot guilty after watching the film

Results: more witnesses stated that they were 100% confident
Same reults for suspect in diguise, weapon focus and retentioninterval 63% 

Conclusion: confidence is a poor predictor of witness accuracy, the truth that jurors place in cofidence of the witness is undiminished even if the judge advises that the jury to be wary of it.

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Ross - Effects of shields & videotapes (children)

Aim: if use of protective shields/videotaped testimony increases likelihood of a guilty verdict

Method/Design: lab exp - mock trial, 3 conditions 100 p in each
1. Control condition - child witness full view
2. Screen condition - child witness behind a 4' by 6' screeen
3. Video condition - child gave evidence by video link in another room

Participants: 300 psych students 150M&150F intro psych course, most white & middle class

Procedure: ps watched 1 of 3 2hour films. Alleged abuse - father gave a single touch while child had bath, Q whether it was innocent or sexual in nature. Judge read warning before screen /video was used, clearly directing jury no to imply guilt by their use. Ps gave verdict, rated credibility of child witness on various aspects of her story & rated defendant on his credibility.

Results: no signif diff across conditions. Guilty= control 51%, shield465, video 49%
however, signif diff between M&F ps, 59%F against 39%M found defendent guilty

Conclusion: suggest protecitve shields & viodetapes testimonies can be used for child witnes in a way so it deosnt prejudice the jury against them. Jurors should be warned not to imply guilt/innocent from use of screens/videotapes

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Hastie - Stages in decision making & influences

Aim: to offer a model of stages of jury decision making

Orientation: - relaxed and open discussion
- set the agenda 
- raise questions
- different opinions arise

Confrontation: - fierce debate
- focus on minute detail
- pressure on minority to conform
- support for group decision is established

Reconciliation: - decision reached
- tension resolved through humour

Assumption that these stages apply is based on mock juries 

However, there have been many studies that carried out mock/shadow juries and all come to the same conclusion. 

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Asch - Social majority influence

Aim: investigate the effects of comformityto a majority when the task is unambiguous

Method/Design: lab exp, stooges give obviously wrong answer when asked which of the lines A, B, C match line X. Asch wanted to se if even in a crystal clear decision an individual would defer to the majority

Participants: 123 male students (from 3 diff unis) USA

Results: individuals conformed 1/3 occasions, 32% of comformity with 4 stooges drop to 5% of comformtiy when 1 stooge disruots conformity

Conslucion: this shows that the majority can have a signif influence over individuals, however once the majority change their behaviour confomity drops

Majoritie bigger than 3 make little difference to the comformity effect, maybe because 3 is enough to create a group norm while 2 would be insufficient

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Nemeth & Watchler - Majority influence

Aim: to onvestigate the influence of perceived autonomy  & consistency of minority influence

Method/Design: lab exp, mock trial

Participants: 116 male students 18+, groups of 5 on stooge in each

Procedure: deliberate on amount of compensation due from a victim of an injury. Hear facts & individual verdict made, then taken into diff room with rectangular table, 2 seats on either of the long sides and 1 at the head of table. 1/2 the groups ps asked to sit at table with stooge choosing head of table. Other groups, experimenter tells them where to sit. Case is deliberated. During discussion stooge consistently suggests a figure of $3,000 in compensation instead of $10,000-$25,000 which was the view of the rest.

Results: stooge exerts influence when he is consistent & perceived as autonomous because of his seat, seen as more confident. When seated by experimenter he has less influence. 

Conclusion: has an interesting effect for the jury room where people sit around a larger table. There are many examples where minorities have influenced the majority by being consistent. However, it is possible that in the jury room in real life this effect is weakedn by the need for unamity in a limited time. 

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