Eyewitness evidence can play a crucial role in criminal investigations, and, in many instances, eyewitness identifications provide the only substantive evidence available to investigators. Of course, it is also well understood that there are many factors that law enforcement personnel have no control of whatsoever that can adversely affect the reliability of eyewitness accounts, such as the effects of traumatic stress, alcohol intoxication, difficulties related to identifying faces from a different race, poor viewing conditions, and fading memories due to the passage of time.1 Eyewitness researchers generally refer to these factors as estimator variables. In contrast, there are other factors that law enforcement has a great deal of control over that can have profound and predictable effects on witness performance. Eyewitness researchers generally refer to these factors as system variables.2 Some examples of system variables include deciding whether to use a showup or lineup, deciding who should be included as a filler or similar person (or image) in a live or photographic lineup, and deciding what is said to the eyewitness before the identification procedure.3 Beyond the benefit of decreasing errors, the use of sound procedures designed to reduce suggestion can also increase the potency of the prosecutorial evidence, as identifications secured with the use of updated evidence-based methods will be less subject to critiques in court that might discredit the eyewitness evidence and harm the case.
A team composed of both eyewitness scientists and law enforcement personnel has developed the field-simulation paradigm to test a new modified version of the pre-identification instructions initially recommended by the U.S. Department of Justice Technical Working Group for Eyewitness Evidence and more recently endorsed by the National Institute of Justice and the National Academy of Sciences.4 Currently, in most U.S. jurisdictions, pre-identification instructions (i.e., admonitions) inform witnesses before they attempt to make an identification that the culprit may or may not be present and that it is just as important to clear innocent persons as it is to identify the guilty. The recommended modification is that cautionary instructions also include a statement indicating that the investigation will continue regardless of whether an identification is made. This instruction, called the Additional Opportunities Instruction, is designed to relieve witnesses of any pressure they might feel to make an identification.5 Prior to the identification procedure, witnesses are told, “If you do not believe that this is the person you saw, you may have additional opportunities to make an identification later.”
The Field-Simulation Paradigm
Much of what is known about the factors that influence eyewitnesses comes from laboratory experiments. The general assumption is that findings in the lab will apply to witnesses in the real-world.6 Researchers often collaborate with law enforcement to test this assumption by conducting field experiments. Field experiments involve taking procedures that were developed in the lab and testing them in actual cases. This method has worked quite well in the past, and, generally speaking, laboratory findings have been found to generalize well to real-world conditions.7 However, field experiments are not without limitations. The largest limitation of field experiments is that ground truth is unknown. That is, it cannot always be known whether the suspect presented to the witness in a lineup, photo array, or showup is factually innocent or guilty, as witnesses sometimes make mistakes. Even if convictions and/or plea agreements are used as a conservative indication of accuracy, errors can still occur.
The field-simulation paradigm is an attempt to strike better balance between the benefits and limitations of both laboratory and field experiments. This effort represents a new level of collaborative research between law enforcement and behavioral scientists that allows researchers to examine how eyewitnesses perform under realistic field conditions while still maintaining a high level of experimental control. With the field-simulation paradigm, participants witness a staged minor crime under controlled conditions and report the incident to the authorities.8 A uniformed officer responds to the scene to take a report, and witnesses are informed that a suspect has been detained and are asked to take part in some sort of identification test (showup or photographic lineup). Essentially, participants are immersed in what they are led to believe is an actual police investigation that involves the pursuit and apprehension of a suspect and culminates in law enforcement conducting an identification procedure in the field. Unlike field experiments, ground truth is always known and each witness is exposed to the same conditions. These properties permit a more definitive study of what procedures are more likely to result in accurate performance when the actual culprit is presented to them and what factors contribute to errors when witnesses view an innocent suspect.
Showups
Showups involve showing a single suspect to a witness for identification purposes. In day-to-day practice, showups are routinely conducted when officers are in pursuit of a suspect matching a particular description within a circumscribed area shortly after a crime has been reported. When this is done, in most jurisdictions around the United States, individuals who are found in the area shortly after the crime and who match the description of the culprit are detained and presented to the witness, live in the field. Examinations of law enforcement records from various U.S. jurisdictions have indicated that showups are used in 30 percent to 77 percent of identification cases.9
The U.S. Supreme Court recognized problems involved in the use of showups as early as the 1960s, noting that the “practice of showing suspects singly to persons for the purpose of identification, and not as part of a lineup, has been widely condemned.”10 Although Supreme Court rulings have recognized the suggestiveness of showups, rulings on point indicate that showups are permissible in exigent circumstances when time pressures and practical considerations do not permit the use of a less suggestive procedure, such as a photographic or live lineup.11 Indeed, eyewitness experts generally agree with the courts that showups are inherently suggestive, but also recognize their utility in exigent circumstances.12
Examining Witness Performance at Showups with the Field-Simulation Paradigm
Researchers have learned a great deal about witness performance at showups and have established that showups are inferior to lineup procedures.13 However, traditional laboratory paradigms are not designed to capture situational pressures that are brought to bear during the one-to-one confrontation between a suspect and witness in the field. To this end, the field-simulation procedure was designed to examine how the situational pressures witnesses face in the field can influence identification performance, while maintaining the control of a lab experiment.
Recent research using the field-simulation approach at California State University, Los Angeles (Cal State LA) has revealed that the situational pressure placed on a witness in the real world greatly increases the risk of mistaken identification.14 Dr. Mitchell Eisen and his colleagues worked collaboratively with the Los Angeles County Sheriff’s Department and the Cal State LA Department of Public Safety to conduct a series of experiments comparing witnesses who were led to believe the showup was part of an actual investigation to participants who were informed the identification was being conducted as part of a research study. In each experiment, a minor crime (theft of a laptop) was staged repeatedly for small groups of participants under ideal witnessing conditions—long, clear exposure to the thief in a well-lit area—with a 20-minute delay before the showup. The suspect who was presented in police custody was either approximately the same height and weight as the thief or differed by approximately 6 inches and 50 pounds. The thief and the suspect were both Latino males wearing similar clothing.
We found that when participants were led to believe the investigation was real, the false identification rate was consistently high (Exp. 1, 38 percent; Exp. 2, 34 percent; Exp. 3, 40 percent), and was dramatically higher than when witnesses were informed that the identification was being conducted for research purposes (Exp. 1, 14.7 percent; Exp. 2, 9 percent; Exp. 3, 10.3 percent). After removing participants who reported that they suspected the event was being staged for research purposes and looking only at witnesses who reported that they truly believed the crime and investigation were real, the false identification rate was even more alarming in the field condition (Exp. 1, 45.5 percent; Exp. 2, 40 percent; Exp. 3, 50.1 percent). Moreover, when witnesses made identifications in the field, they did so with a high level of confidence regardless of whether they were identifying the actual culprit or an innocent suspect. This latter finding is quite concerning considering that some have suggested that confidence can be a reliable indicator of accuracy with showup procedures.15
The Additional-Opportunities Instruction
As noted earlier, dating back to the 1990s, government agencies have broadly endorsed instructing eyewitnesses that the criminal investigation will continue regardless of whether the witness identifies the suspect. However, the continue-to-investigate instruction had never been empirically tested until recently. Researchers crafted an innovative version of the continue-to-investigate instruction in which participants were informed that if they did not make an identification they would have additional opportunities to see other suspects. Dr. Andrew Smith and his colleagues examined the impact of the additional-opportunities instruction on both guilty-suspect identifications and innocent-suspect identifications. These investigators found that the additional-opportunities instruction drastically reduced false identifications for showups conducted in lab conditions (from 33 percent to 15 percent), but only slightly reduced accurate culprit identifications (from 56 percent to 51 percent).16
Field Testing the Additional-Opportunities Instruction Using the Field-Simulation Paradigm
A recent experiment examined whether the benefits of the additional-opportunities instruction extended to field conditions. The 365 participants were either led to believe they were part of an actual police investigation and that their identification would presumably lead to the arrest and prosecution of the suspect or were told the showup was being conducted for research purposes.17 Participants were randomly assigned to hear either a standard admonition or a modified admonition that included the new additional-opportunities instruction. The standard admonition reads as follows:
You are under no obligation to identify this person as the suspect. We want to have guilty persons identified, but we also want to make sure that innocent persons are cleared of any suspicion in this matter. You should not draw any conclusions about a person just because he is in our custody or handcuffed.
In the modified-admonition condition, the additional-opportunities instruction was added to the end of the standard admonition, and reads as follows:
If you do not believe that this is the person you saw, we will continue to investigate and others may be shown to you later to attempt an identification.
Half the time the actual culprit was presented, and half the time witnesses viewed an innocent suspect who was dressed similarly to the defendant.
Results showed that in the field condition, adding the additional-opportunities instruction decreased false identifications by 23 percent. Specifically, 40 percent of the witnesses falsely identified the innocent suspect when using the standard admonition alone, while only 17 percent made this error when the additional-opportunities instruction was added. Although this instruction decreased false identifications greatly, it had very little effect on accurate identifications, leading to a small non-significant decrease in identifying the actual culprit from 75 percent to 69 percent.18
The effect of the new instruction was even clearer when eliminating the participants who suspected the crime and procedures were staged for research (25.7 percent of participants) and considering only witnesses who reportedly believed the procedures were real and that their identification would presumably lead to the arrest and prosecution of the suspect. In this case, adding the additional-opportunities instruction to the standard admonition resulted in a substantial 32 percent drop in false identifications (51.5 percent vs. 18.4 percent) , but resulted in only a very small, non-significant drop in accuracy when the actual culprit was present (79.4 percent vs. 77.4 percent). This pattern of results is consistent with those of Dr. Smith and his colleagues, and, together, these experiments suggest that the additional-opportunities instruction can reduce innocent suspect identifications significantly while having very little effect on accurate culprit identifications.
Summary and Conclusions
In summary, research examining this newly crafted version of the often recommended continue-to-investigate instruction is very promising. Taken together with the findings of Dr. Smith and his colleagues, the results of the field-simulation experiments suggest that the additional-opportunities instruction has the strong potential to greatly reduce false identifications of innocent suspects without significantly impacting accurate culprit identifications. Also, adding the additional-opportunities statement to the end of whatever admonition a department currently uses is relatively easy to implement, and this small cost-effective change can make a real difference in minimizing errors without compromising accurate identifications.
Dr. Eisen, Dr. Smith, and their colleagues are currently working in collaboration with the Cal State LA Department of Public Safety, using the field-simulation paradigm to test the additional-opportunities instruction with six-pack lineup (lineup of six persons) identifications. In addition to testing the utility of the additional-opportunities instruction when using six-packs and showups, these investigators are testing the efficacy of administering six-packs in the field on a computer or tablet device in an effort to develop alternatives to conducting live showups when feasible.
Notes:
1 Kenneth A. Deffenbacher et al., “A Meta-Analytic Review of the Effects of High Stress on Eyewitness Memory,” Law and Human Behavior 28, no. 6 (December 2004): 687–706; Don J. Read, John C. Yuille, and Patricia Tollestrup, “Recollections of a Robbery,” Law and Human Behavior 16, no. 4 (August 1992): 425–446; Christian A. Meissner and John C. Brigham, “Thirty Years of Investigating the Own-Race Bias in Memory for Faces: A Meta-Analytic Review,” Psychology, Public Policy, and Law 7, No. 1 (March 2001): 3–35; James Michael Lampinen et al., “Effects of Distance on Face Recognition: Implications for Eyewitness Identification,” Psychonomic Bulletin & Review 21, no. 6 (December 2014): 1489–1949; James Sauer et al., “The Effect of Retention Interval on the Confidence-Accuracy Relationship for Eyewitness Identification,” Law and Human Behavior 34, no. 4 (August 2010): 337–347.
2 Gary L. Wells, “Applied Eyewitness-Testimony Research: System Variables and Estimator Variables,” Journal of Personality and Social Psychology 36, no. 12 (December 1978): 1546–1557.
3 Nancy K. Steblay et al., “Eyewitness Accuracy Rates in Police Showup and Lineup Presentations: A Meta-Analytic Comparison,” Law and Human Behavior 27, no. 5 (October 2003): 523–540; Ryan J. Fitzgerald et al., “The Effect of Suspect-Filler Similarity on Eyewitness Identification Decisions: A Meta-Analysis,” Psychology, Public Policy, and Law 19, no. 2 (May 2013): 151–164; Steven E. Clark, “A Re-Examination of the Effects of Biased Lineup Instructions in Eyewitness Identification,” Law and Human Behavior 29, no. 4 (August 2005): 395-424; Nancy K. Steblay, “Social Influence in Eyewitness Recall: A Meta-Analytic Review of Lineup Instruction Effects,” Law and Human Behavior 21, no. 3 (June 1997): 283–297.
4 Technical Working Group on Eyewitness Evidence, Eyewitness Evidence: A Guide for Law Enforcement (Washington, DC: U.S. Department of Justice (DOJ) Office of Justice Programs (OJP) National Institute of Justice (NIJ), October 1999); Technical Working Group for Eyewitness Evidence, Eyewitness Evidence: A Trainer’s Manual for Law Enforcement (Washington, DC: U.S. Department of Justice (DOJ) Office of Justice Programs (OJP) National Institute of Justice (NIJ), September 2003); National Research Council, Identifying the Culprit: Assessing Eyewitness Identification (Washington, DC: The National Academies Press, 2015).
5 Mitchell L. Eisen et al., “An Examination of Showups Conducted by Law Enforcement Using a Field-Simulation Paradigm,” Psychology, Public Policy, and Law 23, no. 1 (February 2017): 1–22; Andrew M. Smith et al., “Eyewitness Identification Performance on Showups Improves With an Additional-Opportunities Instruction: Evidence for Present-Absent Criteria Discrepancy,” Law and Human Behavior 42, no. 3 (June 2018): 215–226.
6 Gary L. Wells and Deah S. Quinlivan, “Suggestive Eyewitness Identification Procedures and the Supreme Court’s Reliability Test in Light of Eyewitness Science: 30 Years Later,” Law and Human Behavior 33, no. 1 (February 2009): 1–24.
7 Gary L. Wells, Nancy K. Steblay, and Jennifer E. Dysart, “Double-Blind Photo Lineups Using Actual Eyewitnesses: An Experimental Test of a Sequential Versus Simultaneous Lineup Procedure,” Law and Human Behavior 39, no. 1 (February 2015): 1–14; Daniel B. Wright and Elin M. Skagerberg, “Postidentification Feedback Affects Real Eyewitnesses,” Psychological Science 18, no. 2 (February 2007): 172–178.
8 Mitchell L. Eisen et al., “Pre-Admonition Suggestion in Live Showups: When Witnesses Learn that the Cops Caught ‘the’ Guy,” Applied Cognitive Psychology 31, no. 5 (2017): 520–529.
9 Dawn McQuiston and Roy S. Malpass, “Eyewitness Identifications in Criminal Cases: An Archival Study,” in Fourth Biennial Meeting of the Society for Applied Research in Memory and Cognition (Kingston, Ontario: 2001); Richard Gonzalez, Phoebe C. Ellsworth, and Maceo Pembroke, “Response Biases in Lineups and Showups,” Journal of Personality and Social Psychology 64, no. 4 (1993): 525–537.
10 Stovall v. Denno, 388 U.S. 293 (1967)
11 Manson v. Braithwaite, 432 U.S. 98 (1977); Neil v. Biggers, 409 U.S. 188 (1972).
12 Miko M. Wilford and Gary L. Wells, “Eyewitness System Variables,” in Reform of Eyewitness Identification Procedures, ed. B. L. Cutler (Washington, DC: American Psychological Association, 2013), 23–43.
13 Steblay et al., “Eyewitness Accuracy Rates.”
14 Eisen et al., “Pre‐Admonition Suggestion in Live Showups.”
15 Melanie Sauerland, Anna Sagana, and Siegfried L. Sporer, “Assessing ‘Nonchoosers; Eyewitness Identification Accuracy from Photographic Showups by Using Confidence and Response Times,” Law and Human Behavior 36, no. 5 (2012): 394–403.
16 Andrew M. Smith et al., “Eyewitness Identification Performance on Showups Improves with Additional-Opportunities Instruction: Evidence for Present-Absent Criteria Discrepancy,” Law and Human Behavior 42, no. 3 (June 2018): 215–226.
17 Eisen et al., “Pre‐Admonition Suggestion in Live Showups.”
18 Eisen et al., “Pre‐Admonition Suggestion in Live Showups.”
