The fallibility of the eyewitness


Eyewitness testimony has held a powerful place in courts for centuries and even now has an impressive hold over juries and judges, over and above forensic evidence. Supreme Court Justice William J. Brennan’s statement in 1981 that “there is almost nothing more convincing than a live human being who takes the stand, points a finger at the defendant, and says, ‘That’s the one!’” has been continuously contested over the last 30 years by numerous case studies, yet hundreds of people are wrongly convicted every year through faulty eyewitness evidence. Gary Wells, a professor of psychology at Iowa State University, has found through his own work and numerous other studies conducted over the last three decades, that there really is almost nothing as unreliable as eyewitness testimony. One particular case study, conducted in 2006, of the reliability of eyewitness evidence also calls into question jurors’ understanding of how memory works, as well as their understanding of how particular factors affect eyewitness reliability, making the problem even more difficult to solve in the courtroom.

As regarded by many psychologists, memory is regarded as trace evidence that is also the most easily corrupted. Factors at crime scenes, such as stress and the presence of weapons, easily interferes with memory and witnesses’ ability to notice detail. Furthermore, information learned after the fact can change what a witness thinks he or she saw; people have the propensity to combine pieces of learned information with witnessed information and mistake that learned information for memory. Interestingly, eyewitnesses’ stated confidence is also no prediction of identification accuracy, and this confidence has shown to be easily influenced by encouragement from others. Even in a simulated crime scene conducted by Wells, using good lighting and close proximity of suspects, seventy percent of participants identified the wrong person. In addition, it has also been found that memory is not only fallible, but in fact changeable. Elizabeth Loftus, from the University of California, Irvine, has shown that during the questioning process of an investigation, changes in wording of questions can change what people think they have witnessed.

Wells more recently began experimenting with how people store facial memories, and has tested approximately 1600 people under 16 different conditions (videotapes, blurred faces, darkened tapes etc.). The idea, he says, is to find the point where witnesses are no longer actually recognising suspects but rather talking themselves into committing to a close match. Wells’ work has led to the implementation of methods that reduce incorrect accusations, as he states that much of mistaken identity has to do with how our memories store faces – not in feature sets but as a whole intact image. However, these methods are still far from fool-proof and have yet to be implemented across the board. Wells hopes that through further documentation and testing, he will be able to devise more precise methods that will give police and jurors increasingly solid means of separating reliable and unreliable testimony and ultimately lead to more accurate convictions.


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