Ecological Validity

Pennington and Hastie believed that jurors’ will construct a story to make sense of evidence and then return the verdict that has the ‘best fit’ with their story. P and H investigated whether the order of testimony had an effect on the jurors’ decisions. The sample used in this study consisted of 130 students from the University of Chicago. The two story-telling strategies investigated in this study are; story order and witness order. Story order is when the Lawyers present evidence in the sequence that events occurred, and witness order is when lawyers present witnesses in the sequence they believe is most likely to persuade the jury (may not be the sequence in which the events occurred, also the benefits of primacy and recency effects are taken into account.

Primacy effect is when for example out of a list of 10 words you are most likely to remember the first word; whereas the recency effect claims you are most likely to remember the last word.

The study was a laboratory experiment, using independent groups design, with ps acting as jurors in a mock trial. The IV was the order of testimony and the DV was the verdict given. In individual cubicles ps listened to a tape recording of the stimulus trial and then responded to written questions. They were told to reach either a guilty or not guilty verdict on a murder charge.

Ps were allocated to one of four conditions. In each condition, the same evidence was presented by the defence and prosecution, only the order of presentation changed (witness or story order).

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The Results of the study showed that the prosecution were most likely to win (78% of guilty verdict) when they used story order and defence used witness order. Similarly, the defence were most likely to win when they used story order and the prosecution used witness order (only 31% guilty verdict). Pennington and Hastie concluded that order of testimony does affect juror’s decisions.

In particular, jurors are more easily persuaded by ‘story order’ than ‘witness order’. P and H also suggested that the reason why 80% of criminal court cases return guilty verdicts in the US is because prosecution lawyers tend to use story order and defence lawyers tend to use witness order. Lawyers use a variety of different techniques in order to persuade a jury, into convincing their client’s innocence. Various studies have been conducted into investigating the best techniques for persuading a jury, but the main issue with many of these studies is that they lack ecological validity. The most common method used in studies investigating persuading a jury, is a laboratory experiment in the form of a mock trial.

Mock trials are often used because, people outside of the jury are not allowed into the jury room due to confidentiality of the legal process. One of the main issues with the use of mock trials is that participants often make an individual decision concerning the verdict of the trial, and are sometimes even asked to give a rating of their belief of the defendant’s guilt. For example in Edwards and Bryan, both of these issues occur, each individual participant gives a verdict as well as a number of ratings concerning their beliefs about the defendant’s guilt or innocence and their views about an appropriate sentence. As in a real court case the jury is only asked to give a verdict of guilty of innocent, which is made in a group decision, the study lacks ecological validity. Another problem with using mock trials is that there is a lack of consequence, meaning the result/verdict given by the participants has no effect on the trial, as in Pennington and Hastie’s study on the effect of order of testimony on jurors’ decisions.

Due to the lack of pressure of wrongfully committing someone of a crime/vice versa as well as the lack of emotional stress associated with serving on a jury in a court room. The study is said to lack ecological validity as it cannot be applied to the real world. Mock trials often present the evidence in various ways, for instance in Pennington and Hastie’s study, the evidence is presented to the participants in individual cubicles, where they listen to a tape recording of the stimulus trial. Another form in which evidence is presented is in Cutler, ps are shown a videotaped robbery trial and in Edwards and Bryan, ps are given a transcript of an actual murder trial in California. Although in Edwards and Bran the transcript is taken from an actual case, the study is still lacking in ecological validity as it is a very different way of gathering data on the trial through a transcript or videotape than it being presented by a lawyer in court.

Often small unrepresentative samples are used due to the use of opportunity sampling. For example in Edwards and Bryan 74 university students are used, as they are all students, the sample is unrepresentative of a typical jury and therefore lowing the ecological validity of the study. Another way in which persuading a jury, can be investigated is via “shadow jury”, this is an alternative to mock trials, and consists of a group of participants who “shadow” i.e. sit in on a case/trial and at the end come to a verdict themselves, and seeing if their opinions are conclusive with the juror’s. Although there are certain advantages to this method such as an improved ecological validity as the participants receive the same amount of evidence as a real jury, presented in a real manner.

However the study still lacks ecological validity due to the lack of consequences, i.e. no pressure of wrongfully committing an innocent person and vice versa. Overall research into persuading a jury is often very lacking in ecological validity due to the laboratory method often used in the form of a mock trial. As these studies have a very low ecological validity, the studies lack applicability to the real world and have low validity in results.