In This Article Eyewitness Testimony

  • Introduction
  • General Overviews
  • Bayesian Estimations and Computational Modeling
  • Face Composites
  • Archival Studies
  • Policy/Practices

Psychology Eyewitness Testimony
by
Gary Wells, Laura Smalarz
  • LAST REVIEWED: 17 May 2016
  • LAST MODIFIED: 29 November 2011
  • DOI: 10.1093/obo/9780199828340-0026

Introduction

Eyewitness testimony is critically important to the justice system. Indeed, it is necessary in all criminal trials to reconstruct facts from past events, and eyewitnesses are commonly very important to this effort. Psychological scientists, however, have challenged many of the assumptions of the legal system and the general public regarding the accuracy of eyewitness accounts. Particularly dominant in the psychological science literature are the views that memory reports are malleable (i.e., changed by suggestive questioning), that witnesses can be made to be extremely confident in inaccurate memories, and that police lineups should follow a careful protocol in order to avoid high rates of mistaken identification. The principal methods used by psychological scientists for examining the accuracy of eyewitnesses involve creating events that unsuspecting people witness and then collecting their reports about what they saw. Because the events were created by the researchers, these reports can be scored for their accuracy and completeness. In this way, researchers can systematically manipulate various factors (such as stress, view, the use of misleading questions, the instructions given prior to a lineup) to determine what variables influence accuracy and completeness. This body of research has its programmatic origins in the mid- to late 1970s, but it received a large boost to its credibility in the 1990s, when forensic DNA testing began to uncover convictions of innocent people. Over 75 percent of these exonerations are cases involving mistaken eyewitness identification. The discovery of these mistaken identifications and resulting wrongful convictions has been a jarring event for the legal system and threatens public faith in the criminal justice system. Accordingly, eyewitness research today is having a larger impact on the legal system as the legal system recognizes that eyewitness errors are leading to faulty trial outcomes. The scientific literature on eyewitness testimony that has emerged is an important development in showing the relevance of social science for helping to solve problems in the legal system. An increased use of eyewitness experts at trial and revisions to how eyewitnesses are interviewed and how lineups are conducted represent concrete legal-system improvements resulting from this line of research.

General Overviews

Loftus 1979 is a superb, easy-to-read entry to the eyewitness area. Despite its age, it remains one of the most cited works in the field and captures many of the core ideas that still hold prominence, especially the idea of post-event memory malleability. Another core idea that was developed around the same time involved distinguishing between system variables and estimator variables. Wells 1978 articulates the view that a premium should be placed on the study of system variables, which can be used to improve the accuracy of eyewitness testimony, rather than estimator variables, which can be used only to estimate the chances of inaccurate testimony. Another central distinction in the eyewitness area is between event memory and person memory. Event memory focuses on recall of details and interviewing techniques (e.g., suggestive questioning). Person memory focuses primarily on the identification of perpetrators from lineups and show-ups as well as facial composites created by witnesses. The first handbook in the eyewitness area is a two-volume set in which the first volume is devoted to event memory (Toglia, et al. 2007) and the second volume is devoted to person memory (Lindsay, et al. 2007). These two volumes have chapters contributed by the top eyewitness experts and represent the most comprehensive sourcebook to date on eyewitness issues. At a more general level, Loftus and Loftus 1980 is a very important article because it shows that there is no scientific basis to presume that long-term memories, once stored, are permanent. It was particularly influential because it called into question the wisdom of using heavy techniques to get at “hidden” memories, which might not actually exist. As a consequence, such techniques could lead to the creation of false memories. Wells, et al. 2006 is a fairly thorough treatment of the person memory and event memory literatures from a system-variable (what can be done to make reports more accurate) perspective.

  • Lindsay, R. C. L., D. F. Ross, J. D. Read, and M. P. Toglia, eds. 2007. The handbook of eyewitness psychology: Memory for people. Vol. 2. Mahwah, NJ: Lawrence Erlbaum.

    E-mail Citation »

    The counterpart volume to the Toglia et al. 2007 chaptered book, this one dealing with memory for people, especially descriptions of people and the identifications of people from lineups and show-ups. This is a superb sourcebook on eyewitness identification evidence.

  • Loftus, E. F. 1979. Eyewitness testimony. Cambridge, MA: Harvard Univ. Press.

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    An award-winning book that describes the author’s empirical studies of eyewitnesses as well as other works around at the time. A very influential book that nicely articulates Loftus’s thesis that memory is susceptible to internal and external influences well after the witnessed event. This book is still worth reading today.

  • Loftus, E. F., and G. R. Loftus. 1980. On the permanence of stored information in the human brain. American Psychologist 35:409–420.

    DOI: 10.1037/0003-066X.35.5.409E-mail Citation »

    An excellent treatment of whether long-term memories, once stored in the brain, are permanent. Many theories have postulated that such memories are permanent and that forgetting is simply a matter of retrieval failure. Loftus and Loftus review the evidence (e.g., hypnosis, brain stimulation studies) and conclude that there is no proof of permanence.

  • Toglia, M. P., J. D. Read, D. F. Ross, and R. C. L. Lindsay, eds. 2007. The handbook of eyewitness psychology: Memory for events. Vol. 1. Mahwah, NJ: Lawrence Erlbaum.

    E-mail Citation »

    A superb set of chapters from top eyewitness experts examining facets of eyewitness memories for events, including memory for conversations, actions, objects, and other details of events. This is a powerful resource book.

  • Wells, G. L. 1978. Applied eyewitness testimony research: System variables and estimator variables. Journal of Personality and Social Psychology 36:1546–1557.

    DOI: 10.1037/0022-3514.36.12.1546E-mail Citation »

    A distinction is made between system variables (e.g., pre-lineup instructions to witnesses), which can be controlled by the justice system, and estimator variables (e.g., how good of a view the witness had), which are not controllable by the justice system. This useful distinction permeates the eyewitness research literature to this day.

  • Wells, G. L., A. Memon, and S. Penrod. 2006. Eyewitness evidence: Improving its probative value. Psychological Science in the Public Interest 7:45–75.

    E-mail Citation »

    A strong review of the scientific literature on factors that can improve the accuracy of eyewitness evidence, including various reforms to how lineups and interviews of eyewitnesses are conducted.

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