Gary L. Wells

• Ph.D.
• DIstinguished Emeritus Professor at Iowa State University

The U.S. Supreme Court's ruling concerning suggestive eyewitness identification procedures (Manson v. Braithwaite, 1977, 432 U.S. 98) has not been revisited by the Court in the intervening 30+ years. Meanwhile, scientific studies of eyewitnesses have progressed and DNA exonerations show that mistaken identification is the primary cause of convictio...

People viewed a security video and tried to identify the gunman from a photospread. The actual gunman was not in the photospread and all eyewitnesses made false identifications ( n = 352). Following the identification, witnesses were given confirming feedback ("Good, you identified the actual suspect"), disconfirming feedback ("Actually, the suspec...

Proposes a distinction between 2 types of applied eyewitness-testimony research: System-variable (SV) research investigates varibles that are manipulable in actual criminal cases (e.g., the structure of a lineup) and, thus, has the potential for reducing the inaccuracies of eyewitnesses; estimator-variable (EV) research, however, investigates varia...

The authors discuss the problem with failing to sample stimuli in social psychological experimentation. Although commonly construed as an issue for external validity, the authors emphasize how failure to sample stimuli also can threaten construct validity. They note some circumstances where the need for stimulus sampling is less obvious and more ob...

We examined whether the potential to distinguish between accurate and inaccurate decisions on eyewitness lineups could be improved by combining information from three witness behaviors: confidence, decision time, and the language that witnesses use to justify their lineup decisions. We assessed the postdictive potential of these variables for both...

Field data from lineups involving real eyewitnesses in criminal investigations reveal that eyewitnesses make errors at alarming rates—in nearly one out of every four lineups. Police investigators can prevent eyewitness misidentifications of innocent suspects by using research-informed procedures to collect eyewitness-identification evidence. Nine s...

We used signal detection modeling of a large data set to show that forensic cartridge-case examiners were highly unlikely to commit false positives or false negatives but appear to be strongly biased against true negatives (Smith & Wells, 2024). Specifically, forensic cartridge-case examiners were far more likely to claim that the results were inco...

General Audience Summary Criminal investigations often hinge on the balance of testimony from forensic scientists. Many of these forensic scientists report on feature-comparison methods where they microscopically compare the features in an evidence sample (found at the crime scene) to the features in a reference sample (associated with the suspect)...

Cartridge-case comparison experts are tasked with determining whether a reference sample associated with the suspect originated from the same source as the evidence sample found at the crime scene. Inconclusive reports have high exculpatory value as they are much more common for actual non-matches than for actual matches. We used a Signal Detection...

Suspect identifications from unbiased lineups (fair lineups) are more accurate than suspect identifications from biased lineups (Wixted & Wells, 2017). We examined whether laypersons were sensitive to the fact that suspect-identification accuracy is higher for unbiased than for biased lineups. Laypersons were presented with biased and unbiased line...

Audio recordings of real eyewitnesses from double-blind lineup sessions in real police investigations are described for two samples: 102 choosers and 162 non-choosers. Blind evaluators coded eyewitness verbalizations. Eyewitnesses’ comments should convey the underlying decision processes associated with their identification decisions. Deliberative...

This article presents key findings from a research project that evaluated the validity and probative value of cartridge-case comparisons under field-based conditions. Decisions provided by 228 trained firearm examiners across the US showed that forensic cartridge-case comparison is characterized by low error rates. However, inconclusive decisions c...

Suspect identifications from unbiased lineups (fair lineups) are more accurate than suspect identifications from biased lineups (Wixted & Wells, 2017). We examined whether laypersons were sensitive to the fact that suspect-identification accuracy is higher for unbiased than for biased lineups. Laypersons were presented with biased and unbiased line...

The field of psychology–law is extremely broad, encompassing a strikingly large range of topic areas in both applied psychology and experimental psychology. Despite the continued and rapid growth of the field, there is no current and comprehensive resource that provides coverage of the major topic areas in the psychology–law field. The Oxford Handb...

Objective: Although there are many lab-based studies demonstrating the utility of confidence and decision time as indicators of eyewitness accuracy, there is almost no research on how well these variables function for lineups in the real world. In two experiments, we examined confidence and decision time associated with real lineups that had been...

This collection of first-person accounts from legendary social psychologists tells the stories behind the science and offers unique insight into the development of the field from the 1950s to the present. One pillar, the grandson of a slave, was inspired by Kenneth Clark. Yet when he entered his PhD program in the 1960s, he was told that race was n...

Research has consistently shown that concealing facial features can hinder subsequent identification. The widespread adoption of face masks due to the COVID-19 pandemic has highlighted the critical and urgent need to discover techniques to improve identification of people wearing face coverings. Despite years of research on face recognition and eye...

General Audience Summary There is consensus among psychological scientists that fair lineups lead to a better trade-off between guilty-suspect identifications and innocent-suspect identifications than do biased lineups. Yet, debate over the mechanism that leads to this fair-lineup advantage abounds. On the one hand, some propose that fair lineups i...

Research has consistently shown that concealing facial features can hinder subsequent identification. The widespread adoption of face masks due to the COVID-19 pandemic has highlighted the critical and urgent need to discover techniques to improve identification of people wearing face coverings. Despite years of research on face recognition and eye...

Eyewitness misidentifications are almost always made with high confidence in the courtroom. The courtroom is where eyewitnesses make their last identification of defendants suspected of (and charged with) committing a crime. But what did those same eyewitnesses do on the first identification test, conducted early in a police investigation? Despite...

Objectives: We assessed recent policy recommendations to collect eyewitnesses' confidence statements in witnesses' own words as opposed to numerically. We conducted an experiment to test whether eyewitnesses' free-report verbal confidence statements are as diagnostic of eyewitness accuracy as their numeric confidence statements and whether the dia...

The development of forensic DNA testing has led to the discovery of hundreds of cases of mistaken eyewitness identification in which innocent people were convicted. Although these discoveries of wrongful convictions from mistaken identification based on DNA testing have been a surprise and shock to the legal system and the public, psychological sci...

Materials from five extant field studies were analyzed to determine the level of structural bias in police lineups. Depending on the jurisdiction, between 33% and 68% of lineups sampled from 1,548 real police lineups scored as suspect-biased using mock-witness proportion score. The suspect did not draw a fair portion of mock-witness picks in 20% of...

We tested whether multiple doses of feedback have cumulative effects on eyewitness-identification confidence. In Experiment 1, participants made mistaken identifications and received or did not receive three forms of confirming feedback: (1) co-witness feedback; (2) vague feedback from the experimenter (“You’ve been a good witness”); and (3) infere...

General Audience Summary Eyewitness-identification testimony from highly confident, yet mistaken eyewitnesses has contributed to hundreds of wrongful convictions in the United States (www.innocenceproject.org, 2020). But this fact is somewhat puzzling because controlled laboratory studies show that eyewitnesses rarely make mistaken identifications...

Despite the prevalence of guilty pleas, we know relatively little about factors that influence the decision to plead. Replicating and extending Dervan and Edkins’ Journal of Criminal Law and Criminology, 103, 1-48. https://doi.org/10.2139/ssrn.2071397, (2013), we conducted two experiments to examine the effects of guilt status, trial penalty, and c...

The conceptual frameworks provided by both the lineups-as-experiments analogy and Signal Detection Theory have proven important to furthering understanding of performance on eyewitness identification-procedures. The lineups-as-experiments analogy proposes that when investigators carry out a lineup procedure, they are acting as experimenters, and sh...

Objective: The Executive Committee of the American Psychology-Law Society (Division 41 of the American Psychological Association) appointed a subcommittee to update the influential 1998 scientific review paper on guidelines for eyewitness identification procedures. Method: This was a collaborative effort by six senior eyewitness researchers, who...

Objective: The Executive Committee of the American Psychology-Law Society (Division 41 of the American Psychological Association) appointed a subcommittee to update the influential 1998 scientific review paper on guidelines for eyewitness identification procedures. Method: This was a collaborative effort by six senior eyewitness researchers, who al...

Scientific advances across a range of disciplines hinge on the ability to make inferences about unobservable theoretical entities on the basis of empirical data patterns. Accurate inferences rely on both discovering valid, replicable data patterns and accurately interpreting those patterns in terms of their implications for theoretical constructs....

The conceptual frameworks provided by both the lineups-as-experiments analogy and Signal Detection Theory have proven important to furthering understanding of performance on eyewitness identification-procedures. The lineups-as-experiments analogy proposes that when investigators carry out a lineup procedure, they are acting as experimenters, and sh...

We examined how giving eyewitnesses a weak recognition experience impacts their identification decisions. In 2 experiments we forced a weak recognition experience for lineups by impairing either encoding or retrieval conditions. In Experiment 1 (n = 245), undergraduate participants were randomly assigned to watch either a clear or a degraded culpri...

Perpetrators often wear disguises like ski masks to hinder subsequent identification by witnesses or law enforcement officials. In criminal cases involving a masked perpetrator, the decision of whether and how to administer a lineup often rests on the investigating officer. To date, no evidence-based recommendations are available for eyewitness ide...

The present article focuses on a utility-based understanding of criminal justice practice regarding eyewitness identifications. We argue that there are 4 distinct types of utility that should be considered when evaluating an identification procedure. These include the utility associated with all identifications, the utility associated with only the...

General Audience Summary A primary concern in eyewitness identification research is determining which of two lineup procedures leads to better applied outcomes. The difficulty in making this determination is that the procedure that leads to more culprit identifications (a benefit) also normally leads to more innocent-suspect identifications (a cost...

Forensic examiners are often exposed to contextual information that can bias their conclusions about evidence samples (e.g., fingerprints, fibers, tool marks). We tested the recently-proposed filler-control method for moderating the biasing effects of contextual information for forensic comparisons. Borrowing from an analogy to eyewitness lineups v...

The United States convicts over 1 million people of felonies each year without affording the resources of a trial. Instead, these convictions are attained by guilty plea. The current research investigated the similarities and differences that would emerge between pleas and confessions when relying on a paradigm originally developed for confession r...

We tested the proposition that when eyewitnesses find it difficult to recognize a suspect (as in a culprit-absent showup), eyewitnesses accept a weaker match to memory for making an identification. We tie this proposition to the basic recognition memory literature, which shows people use lower decision criteria when recognition is made difficult so...

The U.S. legal system increasingly accepts the idea that the confidence expressed by an eyewitness who identified a suspect from a lineup provides little information as to the accuracy of that identification. There was a time when this pessimistic assessment was entirely reasonable because of the questionable eyewitness-identification procedures th...

Nothing is more fundamental to Signal Detection Theory (SDT) than the notion that memory performance decreases as lures become increasingly similar to target items. Yet, Colloff, Wade, and Strange (2016) claimed that the use of high-similarity fillers (lineup lures) increased memory performance relative to low-similarity fillers. We use their data...

Pre-admonition suggestion is an identification-relevant comment made to an eyewitness by a lineup administrator before the lineup admonition. Quinlivan et al. (2012) found that their suggestion inflated mistaken identification rates and retrospective identification. However, the suggestion used was a compound statement, making it unclear which comp...

ROC analysis has recently come in vogue for assessing the underlying discriminability and the applied utility of lineup procedures. Two primary assumptions underlie recommendations that ROC analysis be used to assess the applied utility of lineup procedures: (1) ROC analysis of lineups measures underlying discriminability, and (2) the procedure tha...

Psychologists have made attempts to apply psychological knowledge on eyewitness issues to the legal system for over a century. But it was not until the 1990s that an organization of psychological researchers (the American Psychology-Law Society) made concrete recommendations in a white paper concerning eyewitness identification. These recommendatio...

A showup is an identification procedure in which a lone suspect is presented to the eyewitness for an identification attempt. Showups are commonly used when law enforcement personnel locate a suspect near the scene of a crime in both time and space but lack probable cause to make an arrest. If an eyewitness rejects a suspect from a showup, law enfo...

The U.S. Supreme Court has not reexamined the test for admission of eyewitness identifications that are the product of suggestive procedures in over 35 years (Manson v. Brathwaite, 432 U.S. 98, 1977). Since then, there have been over 218 DNA-based exonerations of individuals who were mistakenly identified, and an extensive and rich scientific liter...

The police lineup is a common tool for eyewitness identifications of suspects in criminal cases. Forensic DNA testing of people convicted by eyewitness identification evidence and field studies of police lineups, however, have revealed that mistaken identification from lineups is not uncommon. Controlled laboratory experiments have isolated numerou...

Our previous article (Wells et al., 2015a. Journal of Applied Research in Memory and Cognition, in press, this issue) showed how ROC analysis of lineups does not measure underlying discriminability or control for response bias. Wixted and Mickes (2015. Journal of Applied Research in Memory and Cognition, in press, this issue) concede these points....

Some researchers have been arguing that eyewitness identification data from lineups should be analyzed using Receiver Operating Characteristic (ROC) analysis because it purportedly measures underlying discriminability. But ROC analysis, which was designed for 2. ×. 2 tasks, does not fit the 3. ×. 2 structure of lineups. Accordingly, ROC proponents...

Objective Our objective was to examine how Amendola and Wixted (A&W, 2014) arrived at their conclusion that eyewitness identifications of suspects from simultaneous lineups were supported better by corroborating evidence than were identifications from sequential lineups. Their cases came from a randomized field experiment by Wells et al. (2014). Me...

Objective Our objective was to assess Amendola and Wixted’s (Journal of Experimental Criminology, 2015b, this issue) response to our critique of their conclusions regarding simultaneous and sequential lineups. Methods We calculated the expected distribution of adjudicated guilty and not guilty cases in the smaller sample of cases for simultaneous a...

Mistaken identification testimony by highly confident eyewitnesses has been involved in approximately 72% of the cases in which innocent people have been convicted and later exonerated by DNA testing. Lab studies of eyewitness identification, however, show that mistaken eyewitnesses are usually not highly confident and that there is a useful confid...

We provide a novel Bayesian treatment of the eyewitness identification problem as it relates to various system variables, such as instruction effects, lineup presentation format, lineup-filler similarity, lineup administrator influence, and show-ups versus lineups. We describe why eyewitness identification is a natural Bayesian problem and how nume...

Eyewitnesses (494) to actual crimes in 4 police jurisdictions were randomly assigned to view simultaneous or sequential photo lineups using laptop computers and double-blind administration. The sequential procedure used in the field experiment mimicked how it is conducted in actual practice (e.g., using a continuation rule, witness does not know ho...

This research examined whether confirming postidentification feedback following a mistaken identification impairs eyewitness memory for the original culprit. We also examined whether the degree of similarity between a mistakenly identified individual and the actual culprit plays a role in memory impairment. Participant-witnesses (N = 145) made mist...

Approximately 75% of DNA exonerations are cases involving mistaken identification. Lab-based experiments by psychological scientists have informed the legal system about ways to reduce the misidentification problem. One of these ideas, the sequential lineup (which shows the witness one lineup member at a time), increases the ratio of accurate to mi...

Eyewitnesses’ retrospective reports of certainty, view, attention, and other judgments constitute central variables used by courts to assess the credibility of eyewitness identification evidence. Recently, important state Supreme Court decisions (e.g., New Jersey v. Henderson, 2011; Oregon v. Lawson, 2012) have relied on psychological research rega...

Giving confirming feedback to mistaken eyewitnesses has robust distorting effects on their retrospective judgments (e.g., how certain they were, their view, etc.). Does feedback harm evaluators' abilities to discriminate between accurate and mistaken identification testimony? Participant-witnesses to a simulated crime made accurate or mistaken iden...

Research-based reforms for collecting eyewitness identification evidence (e.g., unbiased pre-lineup instructions, double-blind administration) have been proposed by psychologists and adopted in increasing numbers of jurisdictions across the United States. It is well known that reducing rates of mistaken identifications can also reduce accurate iden...

Confidence inflation from confirming post-identification feedback is greater when the eyewitness is inaccurate than when the eyewitness is accurate, which is evidence that witnesses infer their confidence from feedback only to the extent that their internal cues are weak. But the accurate/inaccurate asymmetry has alternative interpretations. A crit...

Purpose. Post-conviction DNA exonerations demonstrate a failure of alibis to protect innocent suspects. We contend one reason alibis are not believed is because evaluators underestimate how difficult it is for an innocent person to generate a convincing alibi. We hypothesized that asking evaluators to first generate an alibi of their own would lead...

We examined the additive and interactive effects of pre‐admonition suggestion and lineup instructions (biased or unbiased) on eyewitness identification rates. Participants watched a mock crime video, completed a target‐absent lineup identification, and completed a retrospective memory questionnaire. Prior to attempting an identification, participan...

An increasingly strong case can be made for the argument that mistaken-eyewitness identification is the primary cause of the conviction of the innocent in the United States. The strongest single body of evidence in support of this proposition is the collection of cases in which forensic DNA testing was used to exonerate people who had been convicte...

Recent research in decision-making has demonstrated the "dud-alternative effect"--the tendency to become more confident that a chosen response option is correct if it is surrounded by implausible response options (Windschitl & Chambers, J Exp Psychol 30:198-215, 2004). This finding may be applicable to a lineup task: The presence of duds (i.e., hig...

In the American legal system, one of the safeguards against wrongful convictions on the basis of mistaken eyewitness identification is the right of the defense to file motions to suppress suggestive eyewitness identifications. These pretrial motions to suppress eyewitness identification evidence are filed routinely, and yet they almost never succee...

We examined whether post-identification feedback and suspicion affect accurate eyewitnesses. Participants viewed a video event and then made a lineup decision from a target-present photo lineup. Regardless of accuracy, the experimenter either, informed participants that they made a correct lineup decision or gave no information regarding their line...

Drawing on the psychological principle that proximal consequences influence behavior more strongly than distal consequences, the authors tested the hypothesis that criminal suspects exhibit a short-sightedness during police interrogation that increases their risk for confession. Consistent with this hypothesis, Experiment 1 showed that participants...

A decade ago, a meta-analysis showed that identification of a suspect from a sequential lineup versus a simultaneous lineup was more diagnostic of guilt (Steblay, Dysart, Fulero, & Lindsay, 2001). Since then, controversy and debate regarding sequential superiority has emerged. We report the results of a new meta-analysis involving 72 tests of simul...

Eyewitness identifications play an important role in many police investigations and courtroom decisions. Identification decision accuracy is shaped not only by the quality of a witness's memory but also by social-influence variables. Some variables can be categorized as general impairments, whereas others produce biases against a specific suspect....

There is broad consensus among researchers both that faces are processed more holistically than other objects and that this type of processing is beneficial. We predicted that holistic processing of faces also involves a cost, namely, a diminished ability to localize change. This study (N = 150) utilized a modified change-blindness paradigm in whic...

Suggesting to eyewitnesses who mistakenly identify someone from a lineup that they identified the right person leads them to recall having been more certain, having a better view during witnessing, and having paid closer attention during witnessing. The post-identification feedback effect is robust and has profound forensic implications because the...

Mistaken eyewitness identification is the primary cause of the conviction of innocent people. Psychological scientists have accumulated considerable knowledge of the factors contributing to mistaken identification. Particular interest has been directed at police lineups. Lineups are sometimes in-person (live lineups) but much more commonly are phot...

Feedback suggestive of mistaken eyewitnesses claiming that they identified the correct person leads to distorted retrospective judgments of certainty, view, and other testimony-relevant measures. This feedback effect can be significantly mitigated if witnesses later learn that the feedback source did not know which lineup member was the correct per...

Two experiments examined the efficacy of an optional deadline lineup procedure for distinguishing correct from incorrect eyewitness identification decisions. The procedure involved briefly presenting the lineup, removing the lineup from view, then giving participants the option of either making an identification decision or viewing the lineup again...

Building a better scientific literature on eyewitness reliability is a continuous process. The articles in this special issue of Applied Cognitive Psychology are timely and well-reasoned reflections on the need to learn from the history of the area, recognize the unique ways in which the legal system operates, and develop better theory. The current...

Can Eyewitness Research Findings Withstand the Legal System's Scrutiny?Are the Findings Just a Matter of Common Knowledge?Does the System itself have Common Knowledge about Eyewitness Identification?Conclusions

Real-world eyewitnesses are often asked whether their lineup responses were affected by various external influences, but it is unknown whether they can accurately answer these types of questions. The witness-report-of-influence mental-correction model is proposed to explain witnesses' reports of influence. Two experiments used a new paradigm (the a...

We examined whether eyewitness identification latencies for sequential line-up decisions indicate an optimum time boundary that reliably discriminates accurate from inaccurate decisions. Participants (N = 381) observed a crime simulation and attempted two separate identifications from target-present or target-absent sequential line-ups. As has prev...

It is not uncommon for there to be multiple eyewitnesses to a crime, each of whom is later shown a lineup. How is the probative value, or diagnosticity, of such multiple-witness identifications to be evaluated? Previous treatments have focused on the diagnosticity of a single eyewitness's response to a lineup (Wells and Lindsay, Psychol. Bull. 3 (1...

We attempt to articulate a theory of lineups by describing the function of lineups. Why is a lineup conducted in actual cases? What is the goal? For example, is the goal to test the memory of the eyewitness? We contend that the answer is no and that the goal instead is to test a hypothesis regarding whether the suspect is the actual perpetrator. We...

Two experiments examined children's metacognitive monitoring of recognition judgments within an eyewitness identification paradigm. A confidence-accuracy (CA) calibration approach was used to examine patterns of calibration, over-/underconfidence, and resolution. In Experiment 1, children (n=619, mean age=11 years 10 months) and adults (n=600) view...