The reliability of witness memories: a review of the factors influencing accuracy in the forensic context

Resumo

Witness memory plays a crucial role in many judicial processes, often being considered one of the main sources of evidence in criminal investigations. However, the reliability of memories reported by witnesses has been widely debated in the scientific literature [1][2][5]. OBJECTIVES: This narrative review examines the main factors that affect the accuracy of witness memories in the forensic context, focusing on cognitive, emotional, and social variables that can distort or compromise the recollection of events. METHODS: In this narrative literature review, we aim to understand the current state of knowledge in our field of study. We conducted searches across various renowned databases, such as PsycINFO, PubMed, EMBASE, Web of Science, Cochrane, Google, and CINAH. We followed APA 7 guidelines. However, it is important to recognize that our narrative is just one among many possible ones. Each literature review brings with it a unique perspective, influenced by the selection of studies, the interpretation of data, and the underlying assumptions of the researcher. RESULTS: First, we discuss the impact of suggestibility, a widely recognised factor that can influence witnesses to alter their memories in response to external suggestions, whether through leading questions, statements from authorities, or social interactions. Suggestibility is particularly relevant in police interviews and interrogations, where inadequate information-gathering techniques can introduce significant biases into witnesses' recollections. Reviews of experimental studies indicate that both adults and children are susceptible to these influences, with children being especially vulnerable. Another factor explored is the effect of stress and trauma at the time of the event and during the recall process. Evidence suggests that high levels of stress can either compromise or strengthen memories, depending on the intensity of the event and the witness's resilience. While the "tunnel memory" theory suggests that central details may be recalled more accurately in stressful situations, peripheral details are often impaired. In addition, the review addresses the role of time between the event and the report. Natural forgetting, combined with subsequent exposure to incorrect or new information, can lead to distortions in witness memories. The literature shows that memory is not static, and each recollection can be reconstructed based on new information, resulting in "contamination" of the original memory. Another relevant aspect is individual differences, such as age and level of cognitive development, which can affect the ability to testify accurately. Children, adolescents, and the elderly exhibit distinct vulnerabilities in relation to memory accuracy, whether due to a lack of cognitive maturation or the decline of memory functions. Finally, the review discusses interview techniques that can mitigate the risk of memory distortions, such as the Cognitive Interview, which seeks to recover information without directly influencing the witness. Such techniques are widely recommended to reduce the impact of biases and increase the accuracy of reported memories [1][2][3][4][5]. CONCLUSION: Witness memory is highly malleable and subject to multiple influences that affect its reliability. Understanding these factors is essential to improving the accuracy of witness evidence in the forensic context, ensuring that the justice system minimises the risk of judicial errors based on distorted or inaccurate memories.