Lineup presentations Through staged crime experiments involving unsuspecting participants, Wells' research has significantly shaped a scientific understanding of issues surrounding the reliability of eyewitness identification evidence, and highlighting the role that inadequate lineup procedures play in leading to mistaken eyewitness identification, and fostering false confidence amongst eyewitnesses. Wells introduced the idea of double-blind lineups, in which the administrator conducting the lineup does not know who the suspect is. The idea of the double-blind lineup is to prevent inadvertent influence on the eyewitness from the lineup administrator. Double-blind lineup procedures are now required in many states and individual jurisdictions across the United States. In 2014, a report from a study committee the
National Academy of Sciences endorsed the idea that all lineups should be conducted using double-blind procedures. Wells also developed a method of lineup fairness known as the functional lineup size, differentiates between the total number of people in a lineup and the number of fillers (i.e., innocent stand ins who fit the description). In the 1990s, Wells and his Ph.D. student
Amy Bradfield Douglass discovered that the confidence that eyewitnesses express in their identifications is highly malleable and can be dramatically inflated after making a mistaken identification through simple comments that seem to confirm their choice, a phenomenon known as the post-identification feedback. In 2011, Wells and Penrod, reviewed the effectiveness of current metrologies for studying eyewitness identification. overall, they recommend a mixed-methods approach, but caution researchers to ground their conclusions within the scope of their methodology. In a
field experiment across four police departments, Wells and Colleagues found that roughly one-third of all eyewitness identifications incorrectly identified an innocent filler from the lineup.
System and estimator variables In an influential article, Wells (1978) introduced the distinction between system and estimator variables. System variables, such as identification procedures, can be controlled and, therefore, improved upon. Comparatively, estimator variables, such as the length of time the witness saw the suspect, cannot be controlled and, therefore, their impact on the case must be estimated. Wells proposed that research on system variables was considered more applicable to real-world settings because it could direct the development of procedures to reduce mistaken identifications. He further argued that the rate of misidentifications is often affected by methodological biases in how identifications are conducted by law enforcement. The differentiation between system and estimator variables introduced by Wells has since become essential in the field of eyewitness identification and the terminology has since become widely adopted in eyewitness research.
Bayesian statistics Wells introduced the application of bayesian statistics to determine the accuracy rates of eyewitness identification. Wells has further developed these Bayesian methods to show how the amount of information (about guilt) gained from eyewitness identification evidence can be quite small and is highly dependent on other (non-witness) evidence.
Publications Wells has authored over 200 chapters in books on his research dealing with eyewitness memory and eyewitness testimony. Some of the most notable journals that Wells has been published in include
Psychological Bulletin,
American Psychologist,
Journal of Personality and Social Psychology,
Journal of Experimental Psychology: Applied,
Psychological Science,
Law and Human Behavior, and
Journal of Applied Psychology. Wells also co-authored Eyewitness Testimony: Psychological Perspectives, with
Elizabeth Loftus which published on May 25, 1984. The book examines topics such as eyewitness memory as a function of age, the adequacy of intuition in judging eyewitness memory, and the relationship between confidence and accuracy. ==Real world implications==