Older adults may be unreliable eyewitnesses, study shows

February 21st, 2007 in Other Sciences / Other

A University of Virginia study suggests that older adults are not only more inclined than younger adults to make errors in recollecting details that have been suggested to them, but are also more likely than younger people to have a very high level of confidence in their recollections, even when wrong. The finding has implications regarding the reliability of older persons’ eyewitness testimonies in courtrooms.

The study, "I misremember it well: Why older adults are unreliable eyewitnesses," is published in a recent issue of the Psychonomic Bulletin & Review. "There are potentially significant practical implications to these results as confident but mistaken eyewitness testimony may be the largest cause of wrongful convictions in the United States," said Chad Dodson, the study’s lead researcher and an assistant professor of psychology at the University of Virginia. "Given that older adults will constitute an increasing proportion of the U.S. population, there may be a corresponding increase in the occurrence of wrongful convictions based on the testimony of highly confident but mistaken eyewitnesses."

Dodson and U.Va. graduate student Lacy Krueger studied "suggestibility errors," instances where people come to believe that a particular event occurred, when in fact, the event was merely suggested to them and did not actually occur.

They found through a series of experiments that when younger and older adults were matched on their overall memory for experienced events, both groups showed comparable rates of suggestibility errors in which they claimed to have seen events in a video that had been suggested in a subsequent questionnaire. However, older adults were "alarmingly" likely to commit these suggestibility errors when they were most confident about the correctness of their response. Younger people were more likely to commit these errors when they were uncertain about the accuracy of their response.

Previous studies by other investigators have shown that older adults are more likely than younger people to "remember" events that did not occur, and to misremember events that did occur. The U.Va. study further suggest that this occurs because older adults are more inclined to miscombine details of events, which results in a high degree of confidence that they are remembering these details accurately.

Participants in the study were shown a five-minute video clip reenacting a burglary and police chase. They were then asked to answer 24 yes/no questions about what they had witnessed in the video. Eight of those questions referred to details that never actually happened in the video, such as suggesting the presence of a gun when in fact no gun ever appeared in the video itself.

Prior to completing the memory test, the participants were told that some of the test questions would refer to details that had not actually occurred in the video. They were asked to indicate for each test question whether it had occurred in the video only, in the questionnaire only, or neither. They were also asked to judge the likely accuracy of their response, essentially whether they were guessing or certain. It was here that the confidence level, even when wrong, was much higher among older adults than younger adults.

"This finding suggests that this is not simply a case of poorer memory among older adults, but that there may be some other mechanism leading to the high rate of confidence," Dodson said. "We believe the high confidence comes from the detail that they believe they remember. Because the detail seems sharp, they are highly confident that they are correct in their recollection, even when the recollection has been suggested to them rather than actually witnessed. This pattern of behavior is particularly worrisome, given the influence of eyewitness confidence on jury decision making."

The older study participants were 60 to 80 years of age, while the younger participants were college students. There were three study groups: the older participants who all took the questionnaire immediately after seeing the video, a young group who also took the questionnaire immediately after seeing the video, and a group of younger participants who answered the questionnaire two days after seeing the video to replicate the memory differences between older and younger adults.

Source: University of Virginia

"Older adults may be unreliable eyewitnesses, study shows." February 21st, 2007. http://phys.org/news91291760.html