Memory distortion and misperception in the criminal justice system
The legal system relies on witnesses to recall and recount their experiences accurately. Allegations of historic sexual abuse, for example, tend to involve little or no corroborating evidence, meaning that cases are often built solely on the complainant’s recollections. A large body of research demonstrates that exposure to post-event information can distort memory for past experiences, but research has yet to examine how processes inherent to the criminal justice system could also affect memory. In this thesis, we explored how two unavoidable aspects of the criminal investigation process—the decision to report a crime (Study 1) and the metacognitive experience of recall difficulty (Study 2)—could impair memory. We also investigated potential jurors’ awareness of how memory can be distorted (Study 3). In Study 1a, we investigated whether the decision to report a crime is associated with memory distortion. Participants watched a video of a man walking around the outside of a house, and chose whether or not they would report him to the police. One week later, participants returned to the laboratory for a surprise free recall and recognition memory test. We found that the decision to report the target was associated with increased correct and incorrect endorsement of burglar-consistent details, but only in the recognition memory test. In Study 1b, we investigated the possibility that these memory distortions could have occurred before participants made their decision. Participants underwent the same procedure as Study 1a, but this time we asked participants to imagine that they had made the opposite decision. In contrast to Study 1a, there were no between-group differences in memory—in either the recognition memory test or during free recall. In Study 2, we investigated how the metacognitive experience of recall difficulty could affect people’s evaluations of childhood, and the retrieval strategies used to bring memories to mind. Participants recalled either 3 or 8 memories of positive or negative events from childhood, and then rated how well they remember their childhood and how pleasant their childhood was. We also asked participants which retrieval strategies they used to bring memories to mind. Participants who recalled more negative memories rated their memory for childhood as poorer than those who recalled fewer, while the opposite was true for participants who recalled positive memories. We also showed that participants who were asked to recall more memories were more likely to use retrieval strategies that have the potential to distort memory, such as speculation. In Study 3, we used the Beliefs about Memory Survey (BAMS) to explore laypeople’s knowledge and beliefs about memory. Overall, although participants were aware that memory can be inaccurate, they still held some misconceptions—particularly regarding memory for traumatic events. We also assessed whether these beliefs were stable—on a societal level and at an individual level—by comparing our own data to data collected 25 years ago. Our findings revealed that some beliefs show age-related changes (e.g., about memory permanence), while others were susceptible to societal shifts (e.g., about repression of traumatic memories). Taken together, these findings uncover new routes via which eyewitnesses’ memories could be distorted, but—more promisingly—they also suggest that potential jurors are increasingly aware of the ways in which memory can be unreliable. A key focus now, then, should be on ways to improve laypeople’s application of that knowledge in legal contexts.
Advisor: Zajac, Rachel
Degree Name: Doctor of Philosophy
Degree Discipline: Psychology
Publisher: University of Otago
Keywords: Criminal justice system; Eyewitness testimony; Memory beliefs; Memory distortion; Misinformation
Research Type: Thesis