Snap Shot
- The question: How reliable is an identification made when police present a single suspect to a witness, usually soon after a crime and near the scene, and how does it compare with a lineup?
- What the research shows: Witnesses choose less often from show-ups than from lineups, and correct identifications of a guilty suspect occur at roughly similar rates. When the person shown is innocent but resembles the culprit, show-ups generally produce more identifications of that innocent person, and analyses that weigh correct against false identifications generally find lineups more diagnostic. Delay, clothing that matches the culprit’s, and cues that the person is in custody increase risk.
- What it does not show: The research does not show that show-up identifications are usually wrong, that a lineup held days later is always better than a show-up held minutes after the event, or that a particular show-up identification is accurate or mistaken. Field data cannot tell how many identified suspects were guilty.
- The law: Show-ups are judged under the due process framework of Stovall, Biggers, Manson, and Perry; in courts-martial under Mil. R. Evid. 321 and United States v. Baker and United States v. Criswell; and in Arizona through a Dessureault hearing, where the State must show by clear and convincing evidence that an inherently suggestive identification is nonetheless reliable (State v. Rojo-Valenzuela).
- Issues for each side: Prosecutors should document why a show-up was used, how it was conducted, and the witness’s first confidence statement, without treating a positive show-up as equal in weight to a fair lineup; defense counsel should focus on delay, clothing, custody cues, and repeated procedures, recognizing that a prompt, well-conducted show-up has legitimate value and also clears innocent people.
In a show-up, police present a single person, the suspect, to a witness and ask whether this is the person the witness saw. A lineup, by contrast, places the suspect among known-innocent fillers. Show-ups usually take place in the field within minutes or hours of a crime, after officers stop someone near the scene who fits a description, and they are among the most common identification procedures in practice. In one set of archival cases as summarized by Lane and Houston (2021, p. 154; the primary archival study was not reviewed for this paper), show-ups accounted for more than half of the identifications studied.
Show-ups reach court because the procedure tells the witness, by its structure, whom the police suspect. Courts have long described single-suspect presentations as suggestive, yet they also recognize that a prompt show-up can be necessary, can capture a witness’s memory while it is fresh, and can quickly release an innocent person who happens to match a description. The science and the law both address that tension.
This paper summarizes the comparative research on show-ups and lineups and how its figures should be read, the effects of timing, clothing, and repeated show-ups, current scientific recommendations, and the federal, military, and Arizona law governing show-up identifications.
What a Show-Up Is and Why It Is Used
In a lineup, a witness who is guessing or who has a weak memory may pick a filler, a known error that does not endanger an innocent suspect and that reveals the weakness of the witness’s memory. A show-up has no fillers. Every positive identification falls on the suspect, and the procedure itself cannot distinguish a witness who recognizes the person from one responding to the situation: a single person, often beside officers or in handcuffs, presented shortly after a crime.
The investigative reasons for show-ups are real. Police who detain someone near a scene may lack probable cause to hold the person for a later lineup; a show-up lets them develop probable cause or release the person promptly, tests memory while it is freshest, and lets officers resume searching quickly. A rejection of an innocent person is itself a valuable result, and witnesses reject show-ups more often than lineups. For these reasons, researchers critical of show-ups have generally recommended constraining and improving them rather than abolishing them (Wells et al., 2020).
What the Comparative Research Shows
The foundational synthesis is the meta-analysis of Steblay, Dysart, Fulero, and Lindsay (2003), which pooled 12 tests from eight papers with 3,013 participants; every test used six-person lineups, unbiased instructions, and a single culprit. Across conditions, witnesses chose someone about half as often from a show-up as from a lineup (27% compared with 54%). In culprit-present conditions, fewer show-up than lineup witnesses made any choice (46% compared with 71%, in the nine tests reporting this), yet correct identifications of the culprit were nearly identical (47% compared with 45%, a nonsignificant difference), because every show-up choice was the culprit while 24% of lineup witnesses picked a filler. In culprit-absent conditions, show-up witnesses correctly rejected more often (85% compared with 57%) and chose less often (15% compared with 43%) (Steblay et al., 2003).
How to read the culprit-absent results is the central question, because every mistaken show-up choice falls on the suspect, whereas most mistaken lineup choices fall on fillers. Only five tests reported filler and suspect choices separately. In those tests the 41% lineup error rate consisted of 31% filler picks and 10% picks of the designated innocent suspect, against 15% show-up false identifications. When the authors instead dropped witnesses who chose a filler from the lineup analysis, lineups produced 84% correct rejections and 16% innocent-suspect identifications, nearly matching show-ups (85% and 15%). Results differed when the innocent suspect resembled the culprit. In the three tests that planted a look-alike innocent suspect, show-ups produced 23% false identifications of that person, compared with 10% of all lineup decisions and 17% with filler choices excluded; the latter difference was marginally significant (p = .06). When the innocent suspect was not chosen for resemblance, the rates were 15% and 16%. The authors also described a different estimate that divides the culprit-absent lineup choosing rate by lineup size (43% divided by 6, about 7%), well below the 15% show-up rate, and noted that it holds only if an innocent lineup suspect is chosen no more often than any filler (Steblay et al., 2003).
Later laboratory studies using receiver operating characteristic (ROC) analysis, which measures how well a procedure separates guilty from innocent suspects across levels of confidence, have generally found lineups more diagnostic than show-ups (Gronlund et al., 2012; Wetmore et al., 2015). A comprehensive review of the show-up literature concluded that researchers had not identified circumstances in which a show-up outperformed a lineup held at the same time; whether a prompt show-up outperforms a later lineup has seldom been tested directly (Neuschatz et al., 2016). In experiments with more than 3,600 participants, showing similar faces beside the suspect, even faces that could not be chosen, improved discrimination of guilty from innocent suspects, suggesting that lineups help because witnesses can compare faces, not only because fillers absorb errors (Colloff & Wixted, 2020).
Why Show-Ups Perform Differently
Witnesses set an internal standard, or criterion, for how close a match to memory must be before they make an identification. An early series of studies found that witnesses were more willing to reject a single suspect than a lineup, a difference in response bias rather than in memory (Gonzalez et al., 1993). That more cautious overall criterion explains the lower choosing rate for show-ups.
The criterion is not fixed. In an experiment with 610 participants, witnesses told they would have other opportunities to identify someone made fewer identifications of an innocent suspect (15% compared with 33%) with a smaller drop in culprit identifications (51% compared with 57%), while the standard may-or-may-not-be-present admonition had no measurable effect. The authors concluded that when no face truly matches, witnesses accept a weaker match rather than miss a chance to identify the culprit (Smith et al., 2018).
Real-world stakes also matter. In a field-simulation experiment in which participants witnessed a staged theft, uniformed officers conducted the identification procedure for some participants, who believed the investigation was real, while others knew they were in a study. Under field conditions, witnesses lowered their criterion for choosing from show-ups and were overconfident in those identifications, whereas with lineups they became more cautious, and high-confidence identifications were more often correct from lineups (Eisen et al., 2022). Laboratory studies may therefore understate, or otherwise misstate, the risk of a field show-up; this rests on a single field-simulation study (Eisen et al., 2022), not on real crimes.
Timing, Clothing, and the Innocent Suspect
Timing is the strongest argument for show-ups. A show-up conducted minutes after an event tests a fresher memory than a lineup conducted days later, and identification accuracy generally declines with delay. Archival data from actual cases show suspect-identification rates in photographic lineups declining over time (Behrman & Davey, 2001). In a study that tested witnesses at delays from immediately to 24 hours, a lookalike innocent suspect was falsely identified more often in show-ups than in six-person lineups (Yarmey et al., 1996). Few laboratory studies have directly tested whether a prompt show-up outperforms a later lineup (e.g., Wetmore et al., 2015). A show-up conducted long after the event loses its main justification.
Clothing is a distinctive risk. Suspects stopped near a scene are often stopped because their clothing matches the description, and witnesses may rely on clothing rather than the face. In experiments, an innocent suspect wearing clothing like the culprit’s was falsely identified more often than one in different clothing (Dysart et al., 2006; Yarmey et al., 1996). A match in clothing is evidence of resemblance to the description, but it does not independently confirm that the witness recognized the face, and a witness may rely on clothing.
Two further issues affect innocent suspects. First, if a witness rejects one show-up suspect, police may detain another and conduct a second show-up. In a series of experiments, the risk that an identified suspect was innocent rose with each additional show-up, because false identifications accumulate even as witnesses become somewhat more cautious after the first rejection; unbiased instructions reduced but did not eliminate the problem (Smith et al., 2014). Second, the suspect’s appearance in a show-up can affect later procedures. A witness who has seen the suspect at a show-up and then views a lineup may recognize the person from the show-up rather than from the crime, so a later lineup containing the same suspect is not an independent test (Wells et al., 2020).
Field data must be read carefully. In an archival analysis of actual cases, witnesses identified the suspect in 76% of field show-ups compared with 48% of photographic lineups (Behrman & Davey, 2001). That difference may reflect suggestion, a higher proportion of guilty suspects among people stopped near a scene shortly after a crime, or both; archival studies cannot determine which suspects were guilty. Jurors may also have difficulty with the distinction. In a 2026 study, mock jurors were insensitive to the accuracy differences between show-up and lineup identifications (Wang et al., 2026).
Current Scientific Recommendations
In 2020 the American Psychology-Law Society published nine recommendations for collecting and preserving eyewitness identification evidence. One recommends avoiding show-ups when a lineup can be conducted and improving how show-ups are conducted when they are necessary (Wells et al., 2020). The improvements discussed parallel lineup safeguards, including telling the witness that the person may not be the culprit, minimizing signs that the person is in custody, obtaining and recording the witness’s confidence at the time of the identification, recording the procedure, and avoiding repeated identification procedures with the same witness and suspect. The recommendations, summarized by Lane and Houston (2021, pp. 143–155), accept that show-ups have a place in police practice.
Limits of the Evidence
Most comparative studies use student or community participants who view a staged event or a video, with no real consequences. The Steblay et al. (2003) meta-analysis rested on 12 tests, and its innocent-suspect comparisons on only three to five; its authors called for more research. Laboratory results may understate or otherwise misstate the risk of field show-ups, because real stress, lighting, and distance are hard to reproduce. ROC analyses measure how well a procedure separates guilty from innocent suspects across a group of witnesses; they do not determine the accuracy of a single identification. Archival field studies capture real conditions but cannot establish ground truth. No group study can say whether a particular witness’s show-up identification is correct.
Questions to Ask About This Research
When the lower choosing rate for show-ups (Steblay et al., 2003) is offered as reassurance, counsel should ask what was counted, because choosing rates do not measure accuracy and the same meta-analysis found more identifications of a resembling innocent suspect from show-ups (23% compared with 17%, marginally significant). When an expert states that show-ups produce two or three times as many false identifications, counsel should ask how the figure was derived: the meta-analysis’s direct count found nearly equal rates once filler choices were excluded, while its divide-by-lineup-size estimate (about 7% compared with 15%) depends on an assumption about how often an innocent lineup suspect is chosen. When ROC findings are cited (Gronlund et al., 2012; Colloff & Wixted, 2020), counsel should ask whether the laboratory delay, viewing conditions, and instructions resemble the show-up at issue. When field data are cited (Behrman & Davey, 2001), counsel should ask whether the study could know which identified suspects were guilty. These questions are explained in “Reading Research Claims: A Guide for Attorneys” on this site.
Show-Ups and the Law
Federal and Military Standards
The Supreme Court’s framework for suggestive identifications began with show-ups. In Stovall v. Denno (1967), police brought a handcuffed suspect to the hospital room of a gravely injured witness; the Court acknowledged that single-suspect presentations had been widely condemned but found no due process violation because the circumstances made the procedure necessary. Neil v. Biggers (1972), which involved a station-house show-up, and Manson v. Brathwaite (1977), which involved a single photograph, held that an identification obtained through unnecessarily suggestive police procedures may still be admitted if it is reliable under the totality of the circumstances, considering the witness’s opportunity to view, degree of attention, accuracy of the prior description, level of certainty at the confrontation, and the time between the crime and the confrontation. Certainty, in particular, may be inflated by a suggestive procedure. Perry v. New Hampshire (2012) limited the due process screen to suggestive circumstances arranged by law enforcement, leaving other concerns to cross-examination, jury instructions, and the rules of evidence; some state courts, for example in State v. Henderson (N.J. 2011), have revised their frameworks in light of the research. Expert testimony on show-up research is governed by Federal Rule of Evidence 702, as amended December 1, 2023 (the proponent must show it is more likely than not that each requirement is met), Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993), and Kumho Tire Co. v. Carmichael (1999), which extended gatekeeping to all expert testimony.
In courts-martial, Military Rule of Evidence 321 governs eyewitness identification. Under the rule, an identification process is unreliable, and therefore unlawful, if it is so suggestive as to create a substantial likelihood of misidentification; when the defense objects on that ground, the prosecution must prove by a preponderance of the evidence that the identification was reliable under the circumstances, and a later identification may be admitted only if the prosecution proves by clear and convincing evidence that it is not the result of the unreliable one. The Court of Appeals for the Armed Forces has described the inquiry under United States v. Baker (2011) as two questions: whether the procedure was unnecessarily suggestive and, if so, whether it created a substantial likelihood of misidentification. Baker, a government appeal, also held that a service court reviewing such an appeal may act only on matters of law. In United States v. Criswell (2018), an investigator showed a complainant a single photograph of the accused, the military judge assumed the procedure was unnecessarily suggestive (the government offered no contrary proof), and the court held that the judge did not abuse his discretion in admitting the in-court identification, noting that the Rule 321 inquiry is not limited to the five Biggers factors and that a witness’s certainty does not prove accuracy; two judges dissented. Expert testimony is assessed under Military Rule of Evidence 702 and United States v. Houser (1993); Rule 702 tracks the federal rule through Military Rule of Evidence 1102, and practitioners should confirm its current text.
Arizona
Arizona challenges to pretrial identifications are heard at a Dessureault hearing outside the jury’s presence. Under State v. Dessureault (1969), as the Arizona Supreme Court has since described it, the State must prove by clear and convincing evidence that a pretrial identification was not the product of an inherently suggestive procedure or, if it was, that it is nonetheless reliable; an in-court identification following a suggestive pretrial procedure is admissible if it has an independent, untainted basis. The court has characterized one-person show-ups as inherently suggestive while holding that a show-up identification may be admitted if sufficiently reliable under the Biggers factors, which are not exclusive (State v. Williams, 1985; State v. Rojo-Valenzuela, 2015). In Rojo-Valenzuela, an officer who had chased a suspect without seeing his face identified the defendant at a show-up; the court held that an appellate court may decide reliability when the hearing record permits, but that it is highly preferable for the trial court to make those findings before the jury hears the identification. Arizona Rule of Evidence 702 adopted the Daubert standard in 2012 and was amended effective January 1, 2024, to track the federal amendment, and Arizona has long recognized that expert testimony on eyewitness memory may assist jurors (State v. Chapple, 1983).
Special Issues in Legal Practice
The principles described above apply with equal force to every party in a legal proceeding. The science operates the same way regardless of who is asking the questions, and the research summarized here does not by itself favor either side. What differs between the parties is not the science but the vantage point — the particular places where these issues tend to surface, and the particular errors each party is best positioned to guard against. The two summaries below identify those recurring issues. They are offered for orientation, not as litigation strategy; in every case the controlling question is what the evidence in that case will, and will not, support, and the expert’s role is to inform the trier of fact rather than to advocate for either side.
Special Issues for Prosecutors
The research supports several propositions prosecutors can legitimately present. Show-ups serve real investigative purposes, including testing a fresh memory and promptly clearing people who are not the culprit. Correct identifications of a guilty suspect occur at roughly similar rates in show-ups and lineups, and the Steblay et al. (2003) meta-analysis reported approximately equal false identification rates (15% and 16%) when lineup filler choices were set aside. A prompt show-up with neutral instructions, minimal custody cues, and a recorded initial confidence statement is better evidence than one without those safeguards. Documenting why a lineup was not feasible, the time elapsed, what the witness was told, and the witness’s own words lets the factfinder assess the identification on its merits.
The research also counsels caution. When the person shown resembles the culprit but is innocent, show-ups produce more mistaken identifications than fair lineups, and ROC analyses generally favor lineups. A match in clothing does not independently confirm facial recognition, repeated show-ups raise the risk that an identified suspect is innocent, and a later lineup or in-court identification is not an independent test. Certainty first expressed at trial is less informative than confidence recorded at the initial identification, and testimony that treats a show-up identification as equivalent to an identification from a fair, double-blind lineup goes beyond what the research supports.
Special Issues for Defense
The research supports several propositions defense counsel can legitimately present. A show-up presents only the suspect, so a witness’s error cannot fall on a filler, and when the innocent person resembles the culprit, show-ups tend to produce more false identifications than lineups. Delay, clothing that matches the culprit’s, and repeated show-ups increase the risk, the 2020 recommendations treat custody cues as a further source of suggestion, and field conditions may make witnesses more willing to choose and more confident than laboratory studies suggest. Expert testimony explaining these findings, tied to the documented conditions of the show-up, can help the factfinder evaluate the identification.
The research also counsels caution about its limits. Show-ups do not usually produce false identifications; most witnesses reject an innocent person, and correct identifications of the culprit are about as common as in lineups. A prompt show-up tests a fresher memory than a delayed lineup, and the research has not established that a lineup days later would have been more accurate in a given case. Some frequently repeated comparisons, such as statements that show-ups produce two or three times as many false identifications, rest on an estimate the meta-analysis’s authors presented as dependent on an assumption, not on their direct count of errors. An expert cannot tell the factfinder that a particular identification is mistaken; the research describes risk factors, and an identification’s strength also depends on the witness’s view, initial description, initial confidence, and other evidence.
This paper is for educational purposes only and is not legal advice. The author is a psychologist, not an attorney; summaries of law are general and must be verified against current authority or with a licensed attorney.
References
Behrman, B. W., & Davey, S. L. (2001). Eyewitness identification in actual criminal cases: An archival analysis. Law and Human Behavior, 25(5), 475–491. https://doi.org/10.1023/A:1012840831846
Colloff, M. F., & Wixted, J. T. (2020). Why are lineups better than showups? A test of the filler siphoning and enhanced discriminability accounts. Journal of Experimental Psychology: Applied, 26(1), 124–143. https://doi.org/10.1037/xap0000218
Dysart, J. E., Lindsay, R. C. L., & Dupuis, P. R. (2006). Show-ups: The critical issue of clothing bias. Applied Cognitive Psychology, 20(8), 1009–1023. https://doi.org/10.1002/acp.1241
Eisen, M. L., Ying, R. C., Chui, C., & Swaby, M. A. (2022). Comparing witness performance in the field versus the lab: How real-world conditions affect eyewitness decision-making. Law and Human Behavior, 46(3), 175–188. https://doi.org/10.1037/lhb0000485
Gonzalez, R., Ellsworth, P. C., & Pembroke, M. (1993). Response biases in lineups and showups. Journal of Personality and Social Psychology, 64(4), 525–537. https://doi.org/10.1037/0022-3514.64.4.525
Gronlund, S. D., Carlson, C. A., Neuschatz, J. S., Goodsell, C. A., Wetmore, S. A., Wooten, A., & Graham, M. (2012). Showups versus lineups: An evaluation using ROC analysis. Journal of Applied Research in Memory and Cognition, 1(4), 221–228. https://doi.org/10.1016/j.jarmac.2012.09.003
Lane, S. M., & Houston, K. A. (2021). Understanding eyewitness memory: Theory and applications. New York University Press.
Neuschatz, J. S., Wetmore, S. A., Key, K. N., Cash, D. K., Gronlund, S. D., & Goodsell, C. A. (2016). A comprehensive evaluation of showups. In M. K. Miller & B. H. Bornstein (Eds.), Advances in psychology and law (Vol. 1, pp. 43–69). Springer. https://doi.org/10.1007/978-3-319-29406-3_2
Smith, A. M., Bertrand, M., Lindsay, R. C. L., Kalmet, N., Grossman, D., & Provenzano, D. (2014). The impact of multiple show-ups on eyewitness decision-making and innocence risk. Journal of Experimental Psychology: Applied, 20(3), 247–259. https://doi.org/10.1037/xap0000018
Smith, A. M., Wells, G. L., Lindsay, R. C. L., & Myerson, T. (2018). Eyewitness identification performance on showups improves with an additional-opportunities instruction: Evidence for present–absent criteria discrepancy. Law and Human Behavior, 42(3), 215–226. https://doi.org/10.1037/lhb0000284
Steblay, N., Dysart, J., Fulero, S., & Lindsay, R. C. L. (2003). Eyewitness accuracy rates in police showup and lineup presentations: A meta-analytic comparison. Law and Human Behavior, 27(5), 523–540. https://doi.org/10.1023/A:1025438223608
Wang, F., Cash, D. K., & Papesh, M. H. (2026). Mock-jurors are insensitive to accuracy differences between showups and lineups. Psychology, Crime & Law. Advance online publication. https://doi.org/10.1080/1068316X.2026.2699793
Wells, G. L., Kovera, M. B., Douglass, A. B., Brewer, N., Meissner, C. A., & Wixted, J. T. (2020). Policy and procedure recommendations for the collection and preservation of eyewitness identification evidence. Law and Human Behavior, 44(1), 3–36. https://doi.org/10.1037/lhb0000359
Wetmore, S. A., Neuschatz, J. S., Gronlund, S. D., Wooten, A., Goodsell, C. A., & Carlson, C. A. (2015). Effect of retention interval on showup and lineup performance. Journal of Applied Research in Memory and Cognition, 4(1), 8–14. https://doi.org/10.1016/j.jarmac.2014.07.003
Yarmey, A. D., Yarmey, M. J., & Yarmey, A. L. (1996). Accuracy of eyewitness identifications in showups and lineups. Law and Human Behavior, 20(4), 459–477. https://doi.org/10.1007/BF01498981
Legal Authorities
Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).
Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999).
Manson v. Brathwaite, 432 U.S. 98 (1977).
Neil v. Biggers, 409 U.S. 188 (1972).
Perry v. New Hampshire, 565 U.S. 228 (2012).
State v. Chapple, 135 Ariz. 281, 660 P.2d 1208 (1983).
State v. Dessureault, 104 Ariz. 380, 453 P.2d 951 (1969).
State v. Henderson, 208 N.J. 208, 27 A.3d 872 (2011).
State v. Rojo-Valenzuela, 237 Ariz. 448, 352 P.3d 917 (2015).
State v. Williams, 144 Ariz. 433, 698 P.2d 678 (1985).
Stovall v. Denno, 388 U.S. 293 (1967).
United States v. Baker, 70 M.J. 283 (C.A.A.F. 2011).
United States v. Criswell, 78 M.J. 136 (C.A.A.F. 2018).
United States v. Houser, 36 M.J. 392 (C.M.A. 1993).
Fed. R. Evid. 702.
Ariz. R. Evid. 702.
Mil. R. Evid. 321.
Mil. R. Evid. 702.
Mil. R. Evid. 1102.
Related topic papers: Lineup Construction · Confidence and Accuracy · Eyewitness Memory · Improving Eyewitness Memory · Mug Books and Mugshot Exposure · Memory Expert Testimony
Related topics from Arizona Forensic Services: Courts-Martial