magazine issue 11 2015 / Issue 28

Seeing and Believing: Common Courtroom Myths in Eyewitness Memory

• written by Nina Tupper, Melanie Sauerland, Lorraine Hope & Harald Merckelbach
• edited by Emir Efendic

While no study has specifically looked at the possible influence of the number of witnesses on confidence in their stories, we do tend to trust information that comes from multiple (seemingly) independent sources (Harkins & Petty, 1987). Prosecutors take advantage of this by emphasizing that presenting multiple eyewitnesses makes their case particularly strong (Garrett, 2011). However, the mere existence of multiple eyewitnesses telling the same story is not, in itself, proof of accuracy. Multiple witness accounts are reassuring in an investigation, but only if their accounts are both truly independent, and untainted by those very factors to which all eyewitness accounts are vulnerable. Therefore, the reliability of each of these multiple accounts must be subject to the same level of scrutiny as accounts from a single witness.   

Myth # 5: All of This Is Just Common Sense 

Psychology is often thought of as a science of common sense. In fact, in cases when judges bar eyewitness memory experts from testifying, they often rule that the psychologist cannot offer information outside of general common sense (e.g., State v. Coley, 2000). If media reports and court rulings are any indication, then the concept that eyewitnesses are unreliable appears to be generally considered “common sense”. However, surveys suggest that people don’t understand why they distrust memory or what factors can influence the reliability of memory. For example, only 41% of surveyed jury-eligible Americans believe that lineup instructions can impact the accuracy of an identification and only 50% know that eyewitness confidence in that identification is highly susceptible to outside influences (compared to 98% and 95% of memory experts, respectively; Benton, Ross, Bradshaw, Thomas, & Bradshaw, 2006). We find similar disagreements between lay people and experts regarding how the presence of a weapon impacts encoding and how race plays a role in identification (Houston, Hope, Memon, & Read, 2013). A commonsense distrust of memory is not useful if it fails to distinguish between accurate and inaccurate memories or identify the contextual factors that affect memory reliability. As renowned memory researcher, Endel Tulving, once wrote, “Much of science begins as an exploration of common sense, and much of science, if successful, ends if not rejecting it then at least going far beyond it,” (2003, p. 1,505). Common sense is convenient, but it is not sufficiently or consistently well-informed to guide legal judgments with life-altering consequences.