Book review: The Psychology of Eyewitness Identification

The Psychology of Eyewitness Identification describes the complex picture of eyewitnesses’ accuracy when they attempt to identify the perpetrators of a crime. It also describes how different factors, such as those inherent in the witnesses themselves and those present throughout the criminal justice system, impact this accuracy. Although the target audience is not specified, this book might prove a challenge for a person without an interest in – or indeed a love of – cognitive psychology. From the introductory chapter, the tone is set by using a simplified version of a probability theory (the Bayes theorem) to illustrate the number of suspects identified by eyewitnesses from line-ups who are actually innocent of the crime. A less-interested reader might skip over the section providing the different probability calculations without losing sight of the main message: many innocent suspects are put into line-ups and are subsequently identified by eyewitnesses as the perpetrators.

Before tackling the issue of eyewitness identification accuracy, the authors cover a tremendous amount of theory as background information to help the reader understand this issue, particularly in the areas of human memory and human perception of faces. Although the authors suggest that chapter 2 ‘by no means covers all of the theoretical issues relevant to eyewitness identification’ (p. 11), it does an excellent job of covering the major theories well. In some places, however, this coverage feels slightly too extensive as it is not always immediately apparent how the theory will be related to eyewitness identification later in the book. For example, in the section outlining theories of human memory, the authors describe the three basic functional stages of memory processing (encoding, storage and retrieval), of which the relevance can immediately be seen. Slightly less obvious is the application of Atkinson and Shiffrin’s (1968) model of memory and Baddeley’s (2000) working memory model. Although the authors provide helpful eyewitness examples for these models of memory, it is not clear how they fit together (if indeed they do) and when one or the other might be the dominant memory system in a particular situation.

Chapters 3 and 4 provide a comprehensive summary of the major factors that influence the accuracy of eyewitness identifications. Chapter 3 focuses on estimator variables, which are outside of the control of the criminal justice system. These variables include the characteristics of the situation (e.g. level of lighting, viewing time), characteristics of the witness (e.g. age, cognitive ability, intoxication) and characteristics of the perpetrator (e.g. distinctiveness of facial features, disguises). Chapter 4 focuses on system variables, which are factors under the control of the criminal justice system. These factors can occur before the identification of the perpetrator (e.g. exposure to misleading information, hypnosis, making facial composites) and during the identification procedure (e.g. sequential vs simultaneous line-up, double-blind line-up administration). At the end of chapter 4 is a useful summary of the guidelines developed by the American Psychology-Law Society for the collection of identification evidence (Wells et al., 1998). These guidelines should be read by everyone involved in any of the stages during the collection of this crucial evidence.

In one particularly useful chapter, the authors provide a chronological review of the field studies that have been conducted examining eyewitness identification accuracy (chapter 6). Not only do they summarize each of the nine major studies that have been published to date, the authors compare the findings from each of the field studies to the findings from laboratory-based experiments. These comparisons are valuable for expert witnesses who must testify about the research examining eyewitness identification accuracy. Defence lawyers often argue that the laboratory-based research findings have limited applicability because the research was not conducted in ‘real world’ conditions. The authors’ comparison between field and laboratory findings allows us to make statements that show the similarity between these two sets of results. Given the importance of these field studies, it might encourage one to ask ‘why not conduct more field studies?’ The last section of the chapter answers this question through a thorough description of the challenges – and some possible solutions to these challenges – that researchers face when conducting studies in field settings. This chapter segues nicely into the next about expert testimony and issues surrounding eyewitness identification evidence in court.

The authors’ philosophical afterword introducing theories of reasonable beliefs comes as somewhat of a surprise at the end of the book. After a heavy focus on understanding the research behind the factors that influence eyewitness identification accuracy, this turn towards a more philosophical discussion is unexpected. Indeed, there is little that links this discussion of memory and knowledge to the opening chapters in which more mainstream theories of memory were described. These links might have helped the reader to feel that he or she had completed a journey through the world of eyewitness identification accuracy – come full circle, if you will – rather than ending up on a more philosophical branch.