Pennington Hastie
PENNINGTON & HASTIE
Effects of memory structure on judgement.
Aims: To investigate whether or not story evidence summaries are the true cause of a final verdict decision and to what extent these stories will affect the confidence in those final decisions.
Methodology: A lab experiment
Participants: 130 students from
Northwestern University and Chicago
University. The participants were paid for their participation in the 1 hour long experiment. The participants were all allocated to one of four conditions.
• Procedure:
•
The participants all listened to a tape recording of the stimulus trial (Massachusetts v Caldwell) and then were told to respond to written questions.
•
Each of the participants were told to reach either a guilty or not guilty verdict on a murder charge.
•
The participants were all asked to rate their confidence in their own decision on a 5 point scale.
•
They were separated by partitions and therefore were not able to interact with each other.
• Procedure:
•
In the story-order condition, evidence was arranged in its natural order.
•
In the witness order condition, evidence items were arranged in the closest to the original trial.
•
The defence items comprised 39 notguilty pieces of evidence and the prosecution items, 39 guilty pieces of evidence from the original case.
Conditions:
39 PROSECUTION
ITEMS IN STORY
ORDER
39 DEFENCE ITEMS IN
STORY ORDER
39 PROSECUTION ITEMS
IN WITNESS ORDER
39 DEFENCE ITEMS IN
WITNESS ORDER
Results table showing the % of participants choosing a verdict of guilty of murder by prosecution and defence order conditions :
Defence
evidence story order
Defence evidence witness order Mean
Prosecution 59 evidence story order
78
69
Prosecution 31 evidence witness order 63
47
Mean
70
58
45
• Results:
The table shows that story order persuaded more jurors of Caldwell’s guilt in the prosecution case.
• If the defence presented its evidence in witness order, even more jurors would
Effects of memory structure on judgement.
Aims: To investigate whether or not story evidence summaries are the true cause of a final verdict decision and to what extent these stories will affect the confidence in those final decisions.
Methodology: A lab experiment
Participants: 130 students from
Northwestern University and Chicago
University. The participants were paid for their participation in the 1 hour long experiment. The participants were all allocated to one of four conditions.
• Procedure:
•
The participants all listened to a tape recording of the stimulus trial (Massachusetts v Caldwell) and then were told to respond to written questions.
•
Each of the participants were told to reach either a guilty or not guilty verdict on a murder charge.
•
The participants were all asked to rate their confidence in their own decision on a 5 point scale.
•
They were separated by partitions and therefore were not able to interact with each other.
• Procedure:
•
In the story-order condition, evidence was arranged in its natural order.
•
In the witness order condition, evidence items were arranged in the closest to the original trial.
•
The defence items comprised 39 notguilty pieces of evidence and the prosecution items, 39 guilty pieces of evidence from the original case.
Conditions:
39 PROSECUTION
ITEMS IN STORY
ORDER
39 DEFENCE ITEMS IN
STORY ORDER
39 PROSECUTION ITEMS
IN WITNESS ORDER
39 DEFENCE ITEMS IN
WITNESS ORDER
Results table showing the % of participants choosing a verdict of guilty of murder by prosecution and defence order conditions :
Defence
evidence story order
Defence evidence witness order Mean
Prosecution 59 evidence story order
78
69
Prosecution 31 evidence witness order 63
47
Mean
70
58
45
• Results:
The table shows that story order persuaded more jurors of Caldwell’s guilt in the prosecution case.
• If the defence presented its evidence in witness order, even more jurors would