and decision making, but his work on eyewitness evidence has had an outsized impact in psychological science and the legal system. Notable research Lineup presentations Using staged-crime experiments for unsuspecting people, Wells' experiments have shaped a scientific understanding of problems with the reliability of eyewitness identification evidence and the role that poor lineup procedures play in contributing to mistaken eyewitness identification and false confidence on the part of eyewitnesses. Wells introduced the idea of double-blind lineups (Wells, 1990) in, which are lineups conducted by someone who does not know which person in the lineup is the possible suspect and which are merely fillers. 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 introduced a measure of lineup fairness called functional lineup size (Wells et al., 1979) to distinguish between the number of people in a lineup (nominal lineup size) and the ability of the fillers (innocent stand-ins) to make the lineup fair to the suspect. 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 effect. System and estimator variables In an influential article in 1978, Wells proposed a distinction between two different types of variables influencing the accuracy of eyewitness identification (Wells, 1978). System-variables are variables that are (or could be) under the control of the justice system (e.g., pre-lineup instructions to witnesses). Estimator-variables are variables that are not under the control of the justice system, but are circumstantial factors that influence identification (e.g. age, race). Wells proposed that system-variable research would prove to have greater applied utility for criminal justice than estimator-variable research because system-variable research could inform the legal system of ways to reduce the chances of mistaken identification. Wells argued that the rate of misidentifications are influenced by several methodological biases in the methods used by law enforcement to secure the identifications The system-variable versus estimator-variable distinction that Wells introduced in 1978 has so