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

Discrepancies in recall across interviews can be attributed to a number of factors, including asking a witness different questions than the first time (Fisher et al., 2009), or even asking the same questions again (e.g., Erdelyi & Becker, 1974). We often experience this when we tell stories from years-past and have forgotten some details or suddenly recall a detail once-forgotten. Consistency may be valued in the courtroom, but entirely discounting a witness that provides some inconsistent details ignores natural variations in memory recall. 

Myth #4: The More the Merrier! If Several Witnesses Say It, It Must Be True. 

Kirk Bloodsworth, the first man to be exonerated from Death Row in the U.S., was convicted of the rape and murder of a child in 1984, based on the testimony of five eyewitnesses (Junkin, 2004). Osagiede, the Nigerian native, was also identified by two victims. Both cases were prosecuted entirely based on the testimony of multiple eyewitnesses expressing absolute certainty in their identifications – yet both convictions were ultimately overturned at least in part due to unreliable identifications. 

The contribution of multiple witnesses to confirm the events of a crime or identify a suspect inspires confidence in the “facts” presented. Perhaps we can suspect one person’s memory of being faulty, but would five witnesses give the same version of events if it wasn’t true? However, multiple corresponding witness reports do not guarantee accuracy: in a review of 190 exonerees’ transcripts, 36% of the wrongfully-convicted innocents had been identified by multiple eyewitnesses (Garrett, 2011). Ultimately, any memory of a witnessed event is susceptible to external influence, regardless of how many eyewitnesses there are. In the case of Bloodsworth, one of the two boys that saw the victim walk off with the perpetrator identified him immediately from the police lineup. The other boy originally identified a different man, but his mother called two weeks later to report that he had been too afraid to identify Bloodsworth at the time. Several of the other witnesses had independently seen him pictured in handcuffs on the evening news before identifying him in the lineup. The five witnesses had separately arrived at convictions of Bloodsworth’s guilt in different ways, and there is no obvious evidence to suggest that these witnesses influenced each other. However, each of them may have been affected by various factors that influenced their decisions, and they all eventually managed to (inaccurately) confirm the police suspect and build a convincing case for the prosecution. 

Each of multiple witness reports are not only independently vulnerable to the same external influences as all eyewitness evidence, but are also susceptible to the influence of the other witnesses. In the UK, 88% of surveyed witnesses to a crime reported the presence of co-witnesses, more than half of whom had discussed the crime and suspect details with other witnesses (Skagerberg & Wright, 2008). While it is quite understandable that after having observed an upsetting event witnesses want to share their impressions, the pitfall of such conversations is that witnesses can influence each other’s recollections. If witnesses come to know what another has said, they can unconsciously insert these details into their own memory of the event, or leave out important details (Merckelbach, van Roermund, & Candel, 2007). As a result, co-witnesses may (inadvertently) come up with a common version of events – often the version provided by the most confident witness (Wright, Self, & Justice, 2000).   

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.