Computer-Assisted Lineups

Many people are familiar with the live lineups and photo lineups shown in television crime dramas. Increasingly, however, police departments are making use of computer technology to construct lineups and administer them to witnesses. Computer technology can be used to build better lineups by tapping into larger databases of faces to provide better choices to witnesses as well as to provide flexibility and efficiency to officers in the office or the field. Computer-assisted lineups can be administered either simultaneously or sequentially, and they have the added benefits of being programmed exactly to department policy and preserving lineup administration procedures and choices.

Lineup Construction

Researchers at the University of Northern Iowa have developed a Web-based program that allows officers to construct a lineup in the office or in the field. Internet capability (via modem, cable, wireless, or cell phone) allows the computer to link to a central database of faces that can be searched on the basis of a description of the perpetrator. The officer can then construct the lineup. Researchers use a method to evaluate lineups in order to determine if nonsuspect lineup members are serving as adequate fillers. This is referred to as a mock witness evaluation, and it involves providing a person who is not the actual witness with a description of the suspect. The mock witness is then given a lineup and asked to pick out the suspect. If mock witnesses can pick out the suspect at a greater than chance rate, the lineup is said to be biased. Typically, the realization that a lineup is biased occurs well after the lineup administration procedure, usually at the criminal trial. However, the computerized method allows for a mock witness test to be conducted during the course of the investigation, and in the event that the lineup is biased, new lineup members can be selected, thereby avoiding biased lineups being shown to witnesses. The police can accomplish this by sending the lineup and the description of the suspect to officers not associated with the case (across the hall or the state), providing for the lineup to be evaluated prior to administering it.

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Lineup Presentation

Police lineups in the United States have traditionally been administered by presenting the witness a photo array, typically arranged six photos to a page. (These are sometimes referred to as “6-packs.”) In this type of lineup, photos are presented simultaneously, and the witness chooses a photo by pointing at or stating the position number of the lineup member. There has been a recent movement toward administering lineups sequentially, so that witnesses see only one photo at a time. Unlike the simultaneous lineup, in which there is only one lineup decision, witnesses make a decision for each photo in the sequential lineup (“yes” or “no”). One benefit of the sequential lineup is that it has been demonstrated to reduce false identifications of innocent individuals.

Administrator Bias

An additional benefit of the sequential method is that the photos can be randomized so that the administrator does not know which photo the witness is looking at, reducing the likelihood of administrator bias. Administrator bias occurs when the administrator inadvertently gives cues to which photo belongs to the suspect. When neither the administrator nor the witness knows who the suspect is, the procedure is referred to as “double-blind” administration. Computer-assisted lineups provide for reduced interaction between administrator and witness, which greatly reduces the unintentional cues that can pass from the administrator to the witness.

Policy and Procedures

Law enforcement agencies typically have procedures for how lineups should be administered. However, deviations in procedure can easily occur when using traditional hard-copy lineup administration. Not only do computers have the capability to monitor and collect an enormous amount of information, they can also be programmed to administer the lineup exactly in accordance with policy and procedures. The administrator needs only to start the program and then can minimize his or her presence. Computers have the additional benefit of providing both written and audio instructions in any language. Lineups can be administered either simultaneously or sequentially. Lineup members can be randomly assigned to new positions each time the lineup is presented, with the administrator keeping accurate track of the position of each lineup member while recording the time taken to make each lineup decision. Many computers are equipped with condenser microphones and video cameras, thus enabling recording of the exact cursor location as well as audio and video of the event. Depending on the procedures, confidence can be measured for each lineup decision or after the lineup is complete.

Lineup Preservation

Once a lineup decision has been made, the identification information must be recorded and preserved. A multitude of problems can occur in the preservation of hardcopy lineup information: Information about where the photos were gathered from and who the photos represent, along with administration information (who administered the lineup, the date and time, etc.), can easily get lost or not be recorded at all. Evidence obtained using computers can be better preserved than evidence from traditional hard-copy lineups. Lineup evidence in the form of data, photos, audio, and video (including a replay of the entire identification event) can be stored on the computer and automatically copied to a DVD, and it can be uploaded to a departmental server and stored on backup drives for later review by researchers, law enforcement personnel, attorneys, or jurors.


Many identifications occur shortly after the commission of a crime because law enforcement officers often apprehend suspects in the vicinity of the crime. When this occurs, the law enforcement personnel will either bring the witness to the location where the suspect was apprehended or take the suspect to the witness. Either way, this is referred to as a showup. Showups are problematic because both the law enforcement officer and the witness know who the suspect is. Researchers at the University of Northern Iowa have begun experimenting with using handheld personal digital assistants (PDAs) in lieu of showups. PDAs have the ability to take a photo of the suspect and send the photo to a centralized location, either by phone or by WiFi. Technicians at the centralized location can then construct a lineup around the photo and transmit the lineup back to the PDA, allowing the officer to administer a sequential lineup to the witness. One added benefit is that the lineup can be transferred from the suspect’s location to the witness’s location, involving less physical transfer of people and PDAs. The handheld PDA has many of the capabilities of desktop or laptop computers, including playing sound instructions, audio recording the witness’s identification, and transferring the evidence back to a centralized location for preservation.


  1. MacLin, O. H., Meissner, C. A., & Zimmerman, L. A. (2005). PC_Eyewitness: Administration and applications for research in eyewitness identification psychology. Behavior Research Methods, 37, 324-334.
  2. MacLin, O. H., & Phelan, C. (in press). PC_Eyewitness: Evaluating the New Jersey method. Behavior Research Methods.
  3. MacLin, O. H., Zimmerman, L. A., & Malpass, R. S. (2005). PC_Eyewitness and the sequential superiority effect: Computer based lineup administration. Law & Human Behavior, 29(3), 303-321.

Return to the overview of Eyewitness Memory in Forensic Psychology.