A2 Psychology: Unit G543
Options in Applied Psychology
Option:
Topic:
Issue:
Forensic Psychology
Reaching a Verdict
Persuading a Jury
Unit G543: Options in Applied
Psychology
• Health & Clinical
Psychology
– Stress
• Causes of stress
• Measurement of stress
• Management of stress
– Dysfunctional
Behaviour
• Diagnosis of
dysfunctional behaviour
• Explanations for
dysfunctional behaviour
• Treatment for
dysfunctional behaviour
• Forensic
Psychology
– Making a Case
• Interviewing witnesses
• Interviewing suspects
• Creating a profile
– Reaching a verdict
• Persuading a jury
• Witness appeal
• Reaching a verdict
Persuading a Jury:
effect of order on testimony
• Should counsel present their case as a
story unfolding in chronological order?
• Should they use the benefit of the
primacy-recency effect to present their
best witnesses first or last?
– Would this disrupt the order of events in the
jurors mind?
Persuading a Jury:
Pennington & Hastie
Title
• Effects of memory structure on judgement
Aim
• To investigate whether or not story
evidence summaries are true causes of
the final verdict decisions and the extent to
which story order affects confidence in
those decisions
Persuading a Jury:
Pennington & Hastie
Methodology
• A laboratory
experiment
• The 2nd of two
reported in this study
Participants
• 130 students from
Northwestern
University and
Chicago University
• Paid for taking part in
a one-hour
experiment
• Allocated to one of 4
conditions
– Roughly equal
numbers
Persuading a Jury:
Pennington & Hastie
Procedure
• Participants listened to a tape recording of the
stimulus trial (Mass vs Johnson) and then
responded to written questions
• Told to reach either a guilty or not guilty verdict
on a murder charge
• Asked to rate their confidence in their own
decision on a 5 point scale
• They were separated by partitions and did not
interact with each other
Persuading a Jury:
Pennington & Hastie
Procedure continued
• 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 not-guilty
pieces of evidence and the prosecution items, 39
guilty pieces of evidence from the original case
• In all cases, the stimulus trial began with the
indictment and followed the normal procedure,
ending with the judges instructions
The 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
% of participants choosing a verdict of guilty of
murder by prosecution and defence order
conditions
Defence
evidence
story order
59
Prosecution
evidence
story order
Prosecution 31
evidence
witness order
mean
45
Defence
mean
evidence
witness order
78
69
63
47
70
58
Persuading a Jury:
Pennington & Hastie
Results
• The table shows that story order persuaded
more jurors to vote guilty in favour of the
prosecution case
• If the defence presented its evidence in witness
order, even more jurors would find a guilty
verdict
• If the positions were reversed and the defence
had the benefit of story order, the guilty rate
drops to 31%
Persuading a Jury:
Pennington & Hastie
Results continued
• As predicted, the greatest confidence in
their verdict was expressed by those who
heard the defence or prosecution in story
order
• Least confidence was expressed by those
who heard the two-witness order
conditions
Persuading a Jury:
Pennington & Hastie
Discussion
• Because the primacy and recency effects were
controlled for, Pennington & Hastie are confident
that they have shown the persuasive effect of
presenting information in story order
• In this case there is a difference in the defence
case, which seems not to be as persuasive as the
prosecution case, even when presented as a story
– Pennington & Hastie suggest the defence case in the
original trial was not as plausible
• The victim was drunk and lunged forward onto his assailant’s knife