Academic journal article Memory & Cognition

Eyewitness Decisions in Simultaneous and Sequential Lineups: A Dual-Process Signal Detection Theory Analysis

Academic journal article Memory & Cognition

Eyewitness Decisions in Simultaneous and Sequential Lineups: A Dual-Process Signal Detection Theory Analysis

Article excerpt

Many eyewitness researchers have argued for the application of a sequential alternative to the traditional simultaneous lineup, given its role in decreasing false identifications of innocent suspects (sequential superiority effect). However, Ebbesen and Flowe (2002) have recently noted that sequential lineups may merely bring about a shift in response criterion, having no effect on discrimination accuracy. We explored this claim, using a method that allows signal detection theory measures to be collected from eyewitnesses. In three experiments, lineup type was factorially combined with conditions expected to influence response criterion and/or discrimination accuracy. Results were consistent with signal detection theory predictions, including that of a conservative criterion shift with the sequential presentation of lineups. In a fourth experiment, we explored the phenomenological basis for the criterion shift, using the remember-know-guess procedure. In accord with previous research, the criterion shift in sequential lineups was associated with a reduction in familiarity-based responding. It is proposed that the relative similarity between lineup members may create a context in which fluency-based processing is facilitated to a greater extent when lineup members are presented simultaneously.

Wrongful conviction of the innocent is likely the most egregious error that occurs in the criminal justice system. Yet, through the recent advent of DNA testing, exonerations of the innocent are increasing at a rate that few in the criminal justice system would have predicted (Scheck & Neufeld, 2001). Studies in which cases involving wrongful conviction have been examined have consistently indicated that mistaken eyewitness identification evidence is the leading contributing factor (Huff, Rattner, & Sagarin, 1996; Scheck, Neufeld, & Dwyer, 2000). However, findings that mistaken eyewitness identifications frequently lead to wrongful conviction come as no surprise to psychologists who study eyewitness memory (Wells & Olson, 2003). Over the past 20 years, eyewitness researchers have pursued various procedures that might reduce such mistaken identifications in everyday practice.

A much heralded procedural innovation in eyewitness identification was suggested by Lindsay and Wells (1985) and subsequently investigated by Lindsay and colleagues in more than a dozen studies (see Lindsay, 1999). These researchers proposed that the lineup procedure typically used by law enforcement, in which all photographs are presented to the witness at the same time in a simultaneous format, may lead to increased false positive choices as a result of a particular face's being selected on the basis of that individual's familiarity relative to that of others in the lineup. They recommended that an alternative procedure might reduce this reliance upon relative judgments-namely, presenting photographs to the witness one at a time in a sequential format. Lindsay and Wells proposed that such a procedure would encourage the use of what they termed "absolute judgments," based largely on evaluating each face individually.

Since the original Lindsay and Wells (1985) study, a small body of research has accumulated that has demonstrated certain advantages to utilizing such a sequential lineup procedure. In a recent meta-analysis of these studies, Steblay, Dysart, Fulero, and Lindsay (2001) concluded that the sequential lineup does indeed significantly reduce the rate of false identifications when the target is absent from the array, in comparison with performance in the simultaneous lineup (i.e., the sequential superiority effect). However, this reduction occurs at the cost of a lower rate of correct identifications in the sequential lineup when the target is present in the array. Thus, the sequential procedure appears to reduce choosing, regardless of the presence or absence of the target face.

One interpretation of such a pattern has been provided by Ebbesen and Flowe (2002). …

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