Alibis: To Believe or Not to Believe2
will have no impact on the juror’s decision. Therefore, jurors in that condition will not differ from those in the no alibi condition. Finally it was hypothesized that supportive testimony by alibi witnesses will produce fewer guilty verdicts than ambiguous testimony (Culhane and Hosch, 2004).
Participants were 420 Introductory Psychology students who had an average age of 20.46 years old. Participants were asked to complete a voir dire questionnaire and then received one of the fourteen different court cases to read and make a decision on. The variables in the fourteen different cases varied but the general story line was that a man robs a convenience store, is arrested, and put on trial for armed robbery. What the defendant said varied. He was either home alone at the time of the crime, has an alibi and claims that he was home with his girlfriend, or has an alibi that puts him home at the time of the crime with his neighbor witness to this fact. Furthermore, the eyewitness’s confidence is varied. The eyewitness in this case is the store clerk. He is either 100% confident that the perpetrator was the defendant or not 100% confident that the perpetrator was the defendant. The alibi corroborator’s confidence also varied across the conditions, for example, the girlfriend would say something like I can be certain that my boyfriend was with me during the time of the crime, or I cannot be certain that he was with me because I was asleep, etc (Culhane and Hosch, 2004). After each mock juror read their version of the case, they were asked to arrive at an individual verdict. If they found the defendant guilty they were then asked to sentence them to between 5 years and 99 years in prison.
Across all conditions, 45% of the mock jurors voted to convict the defendant. The jurors were least inclined to convict the defendant when the neighbor testified in corroboration and the clerk was not 100% confident and were most inclined to convict when the neighbor denied seeing the defendant and the clerk was 100% confident. In general, Culhane and Hosch found that jurors were more likely to convict the more confident the eyewitness was, that having an alibi
witness testify in corroboration decreased the guilty verdicts, and that jurors convicted less frequently when the neighbor was the corroborator than when the girlfriend testified (see Table 1 of the Appendix). If a neighbor testified on behalf of the defendant, the conviction rate was half the rate when a girlfriend testified or when there was no alibi witness. Only one significant interaction was obtained and that was between the type of alibi witness and the testimony of that witness. When a neighbor testified that she saw the defendant, the number of convictions was reduced significantly from when she was ambiguous and when she did not corroborate with the defendant. The girlfriend’s corroborating alibi also significantly reduced the frequency with which the defendant was convicted in comparison to when she was ambiguous in her testimony. A significant effect was obtained as well when real-world conditions were compared to a no-alibi control condition. When this was the case, the neighbor’s testimony yielded significantly fewer guilty verdicts than when there was no alibi witness or when the defendant’s girlfriend provided alibi testimony. One point to be noted is that the girlfriend’s alibi testimony did not reduce the number of convictions beyond having no alibi at all (Culhane and Hosch, 2004). This proves that in real life, if an alibi were proffered by a relative or person who has a relationship with the defendant, the jury is less likely to believe that alibi.
Mean Guilty Verdicts for All Conditions
WSU Psychology Student Journal, Issue ASarah Shurbert