A2 Psychology at Spalding Grammar School

In 1962 Bennett Murdock Jr carried out some simple lab experiments where participants had to listen to word lists then recall them. Participants tended to recall the words from the start of the list (the PRIMACY EFFECT) better than words from the middle or the end. This might be to do with arousal, since participants are fresh and engaged at the start of a task but then lose interest. This sort of thing is known as the SERIAL POSITION EFFECT and it applies to juries, who will listen attentively to the prosecution’s opening statement but might lose interest by the time the defence gets to speak.

A similar experiment was carried out by Glanzer & Cunitz in 1966, but in the experimental condition the participants were interrupted by having to count backwards before they could start recalling. The interruption increased the primacy effect, with participants forgetting more words from the middle/end of the list but holding on to words from the beginning. This is similar to a trial, where the jury listens to the prosecution, then the defence, but then gets “interrupted” by the judge’s summing-up speech.

Of course, listening to a trial isn’t like memorizing a list of words: the information you are learning is structured, has meaning and tells a story. Nancy Pennington & Reid Hastie (1988) went on to develop the STORY MODEL to account for the serial position effect.

Pennington & Hastie tested 130 students, who were paid for taking part. The students were put into separate cubicles and listened to tape recordings of a trial then answered a questionnaire. In the case, Frank Johnson admitted killing Alan Caldwell outside a bar but the story is ambiguous and the order of events is crucial.

• Was Caldwell a bully who had started the quarrel about his girlfriend?
• Had Johnson stabbed Caldwell or merely held his knife out to protect himself?
• Did Johnson go home to get a knife?

Some participants heard the prosecution evidence, some evidence for the defence; most crucially, some heard the evidence in WITNESS-ORDER and some in STORY-ORDER. Story-order means the order that events actually happened. Witness-order means the order in which witnesses were called up in the original trial. For example, usually the coroner is the first witness and discusses the cause of death (which comes at the end of the story).

Pennington & Hastie looked at the percentage of the mock-jurors who gave guilty verdicts, based on how the evidence had been presented to them: 

Participants were much more confident in their verdict when they heard story-order. Story-order produced more guilty-verdicts than witness-order: 78% for story-order prosecution with witness-order defence, but only 31% the other way round.

Pennington & Hastie’s research suggests that the way trials are structured actually weakens the case. Witnesses are not usually brought to the courtroom in story-order. Usually, the coroner starts the trial by answering questions about the cause of death. The defence will often bring in their best witness first (to take advantage of the primacy effect) and this might be a witness talking about the defendant’s background or good character. The jurors have to put all this into “story-order” for themselves and this seems to confuse them and weaken their certainty in their verdict.

Pennington & Hastie have led the way with this sort of research. They have shown that jurors try to construct a story that uses the most consistent and least discrepant evidence. Most jurors admit that other interpretations are possible but a surprising number construct a single story, often very early during the process, and disregard any evidence that doesn’t fit. These jurors have absolute certainty about their verdict and can’t imagine an alternative.

Juries place a lot of value on eyewitness testimony, especially if the eyewitnesses seem very certain in their recollection. However, psychologists know that eyewitness testimony is very unreliable because of witnessing identifying conditions (WIC):

• Leading questions: as shown by Loftus & Palmer (1974, you studied it for AS), memory is reconstructive and altered by the wording of questions
• Weapons effect: as you learned in Interviewing Witnesses, witnesses’ recollections get confused by the presence of a weapon
• Delayed testimony: the longer the delay, the less reliable the memory; often, court appearances happen a long time after the event being recalled

One solution is to bring before the jury an EXPERT WITNESS – for example, a psychologist who can advise juries that eyewitnesses can be unreliable and explain to them why. Some psychologists (eg McCloskey & Egeth, 1983) have raised alarms about this, arguing that

“it is by no means clear that expert psychological testimony about eyewitnesses would improve jurors’ ability to evaluate eyewitness testimony. In fact, it is even possible that this sort of expert testimony would have detrimental effects.”

In other words, there is a risk that the expert witness would confuse the jurors, making them suspicious of all eyewitnesses. But is this what happens?

Brian Cutler & Steve Penrod have done huge amounts of research into jurors and their perceptions. Most of their work (like this 1989 study) uses mock-juries made up of students (538 in this study) watching a video-taped trial where a witness recalls the events of an armed robbery. Afterwards, the mock-jurors complete a questionnaire which measures the DVs (the innocent/guilty verdict, a memory test about the trial and a scale to measure their certainty about the verdict). In this study, there were four IVs:

1. Witness identifying conditions (WIC): in other words, how reliable were the witnesses in the video? In the “poor” condition” the robber was disguised and armed with a gun, there had been leading questions and a fortnight had passed. In the “good” condition there was no disguise, no visible gun or leading questions and only a 2-day delay
2. Witness confidence: in the “confident” condition, the witness claimed to be 100% confident, but in the “non-confident” condition she was only 80% confident that she had identified the robber correctly
3. Form of expert testimony: in the “descriptive” condition, the expert psychologist used ordinary language to describe how different things affect memory (talking about “small effects” or “large effects”); in the “confusing” condition, he listed lots of percentages taken from actual studies
4. Expert opinion expressed: in half the trials, the expert psychologist would rate the eyewitness on a scale of 0 to 25. Low ratings were given to “poor” WIC conditions and high ratings were given to “good” WIC conditions

The mock-jurors had good (85%) recall of the eyewitness testimony and quite good (50%) recall for what the expert witness had told them. WIC influenced the jurors’ verdict (guilty in the “good” condition) and jurors were more confident when the witness was confident.  Expressed expert opinion did not influence the jurors, but using descriptive expert testimony did make a significant difference, producing more “guilty” verdicts.

This experiment certainly suggests that expert testimony can improve the jurors’ understanding of psychology and make them pay more attention to the WIC. If they pay more attention to WIC they are more likely to tell good eyewitness testimony from bad. It also makes them less influenced by the witness’ confidence and certainty. On the other hand, there’s no evidence that the expert witness made the jurors more suspicious about the witness in general, the accuracy of her identification of the robber or the defendant’s guilt – which is a good thing!

This study, like most of Cutler & Penrod’s research, uses mock-juries made up of students being rewarded with “extra credits” on their introduction to psychology courses. Mock-juries lack ecological validity, because they are looking at a fake trial or a real one that was concluded long ago and their verdicts will not send an innocent man to prison or let a guilty man walk free – nothing’s at stake! This is another study that tests the DVs by getting mock jurors to fill out a questionnaire without conferring. In a real jury, the jurors have to meet together and argue it out, coming up with a group-decision for a verdict.

A practical problem with expert witnesses is that both sides in the trial can call on different ones, who hold different opinions, and the jury is left to decide which expert witness is right! Some expert witnesses are "hired guns" who will take a view on the evidence regardless of what the case is about; so, you have anti-abortion expert witnesses, pro-life expert witnesses, expert witnesses who believe crime is inherited, expert witnesses who don't. The term "junk science" was first used to describe the unusual scientific ideas given to juries by expert witnesses in America.

Expert witnesses are less frequent in Britain. This is partly because of the discrediting of one particular expert witness. Sir Roy Meadow [left] was a child doctor who served as an expert witness in cases where a mother was accused of murdering her baby. In three high-profile cases - those of Sally Clark, Trupti Patel and Angela Cannings - the convictions were overturned on appeal and Meadow's "evidence" was shown to be based on nothing. Expert witnesses today more commonly address the jury on "hard science" topics like fingerprinting or DNA analysis.

Admissible evidence is evidence that can be used in court to persuade the jury. Inadmissible evidence can’t be shown to the jury, for several reasons:

• Hearsay. Quite a lot of evidence is of the “he said this… she said that...” variety. This includes gossip, speculation and rumour. This sort of evidence might prejudice a jury, but it doesn’t prove anything.
• Prior convictions. Some people have criminal records that show they’ve committed crimes in the past. However, you’re supposed to be on trial for this crime, not all your previous ones. Letting a jury know about your previous convictions might prejudice them against you.
• Improper evidence. Some ways of gathering evidence are illegal, like phone-tapping or entering someone’s house without a search warrant. This also includes things said in an interview if the interview wasn’t carried out properly (eg you weren’t allowed to see a solicitor)

In the UK, judges can make a special case to admit some evidence (hearsay, prior convictions, there are plans to admit phone-tapping as evidence in some trials in the future). The main problem is when inadmissible evidence is presented to the jury anyway – due to a mistake, or perhaps because a lawyer is deliberately trying to “sneak” evidence past a judge. If this happens the judge declares that the evidence is inadmissible and instructs the jury to ignore it. But do jurors ignore evidence like this, or does it affect their verdict?

Kerri Pickel has done a lot of research into the perceptions of witnesses and jurors in America. This 1995 study is a mock-trial using 256 students, taking part as part of a course requirement in psychology. The participants listened to an audio recording of a fictional trial for theft. At one point in the trial, a witness refers to the defendant having previous convictions for theft. The defence lawyer objects that this is inadmissible evidence. The mock-trial then changes, depending on the IV:

1. The judge overrules the lawyer, deciding that this evidence is admissible
2. The judge upholds the lawyer and instructs the jury to ignore the evidence of the prior conviction, but offers no further explanation
3. The judge instructs the jury to ignore the evidence and offers an explanation of why it is inadmissible, saying that it might suggest the defendant has a bad character and bias the jury
4. A CONTROL GROUP heard the trial without the inadmissible evidence

After listening to the trial, each participant filled out a questionnaire asking them for their verdict (innocent/guilty), their certainty about their verdict and a rating on a 10-point scale measuring how much knowing about the prior conviction made them think the defendant was guilty.

The results were interesting. Participants who received no explanation ignored the evidence (as they were asked to). We know this because they reached the same "Guilty" verdict as the CONTROL GROUP who didn't even hear the inadmissible evidence. Those who received an explanation of why it was inadmissible didn’t disregard it: they reached the opposite verdict to the control group! Finally, none of the participants believed that the evidence about prior convictions had influenced their verdict.

Pickel’s findings require some explanation. It seems that calling attention to inadmissible evidence makes it seem more important to the jury and they find it harder to ignore it. Their sense of “fair play” comes into effect and they decide whether or not to make use of it. A lengthy explanation from the judge makes it seem as if the defendant is being picked on or perhaps the court is ganging up on them – so jurors go against the inadmissible evidence, allowing their minds to be changed in the opposite direction. This is called REACTANCE THEORY, because the jurors are reacting against the judge trying to tell them what to think and do.

On the other hand, if the evidence is passed over without much comment, then jurors believe it would be wrong to discriminate against someone just because they’ve broken the law in the past and pay no further attention to prior convictions. In short, drawing attention to the reasons for declaring evidence inadmissible can backfire badly.

Reactance theory and the tendency for judges' warnings to backfire were shown in a study by Wolf & Montgomery (1977) who set up a mock-trial where inadmissible evidence obtained through an illegal police stakeout was used. Sometimes this evidence favoured the prosecution, sometimes the defence. The inadmissible evidence never seemed to make any difference to the mock jury's verdict, unless the judge added a warning saying: "This evidence must play no role in your consideration of the case. You have no choice but to disregard it." When this happened, the jurors reacted AGAINST the judge's instruction and arrived at the opposite verdict to the other participants in the same condition.

Pickel’s study, like all the studies in this topic, investigated American courts, where inadmissible evidence can have a bigger impact. In the UK, important inadmissible evidence might cause the jury to be dismissed and a re-trial arranged with a new jury. If the inadmissible evidence is minor, then no one mentions it until a break in the proceedings when the jury leaves. The judge and the lawyers then discuss the inadmissible evidence and when the jury returns they may or may not be told about it and instructed to ignore it. In the USA it is more routine for inadmissible evidence to be “dropped in”, opposing counsel objects and the judge tells the jury to disregard it.