With emphasis bordering on the dramatic, dozens of important articles and books on eyewitness testimony have begun by emphasizing the central, indeed pivotal, role that eyewitness testimony plays in criminal cases. This chapter will be no exception. An eyewitness report, confidently delivered, has swayed many a jury. Even more profoundly, an eyewitness influences the legal process even before the witness takes the stand in court. If there is an eyewitness, especially one who makes a positive impression, the police and prosecutor's office are more likely to pursue a case. And what the witness reports will influence the course of an investigation. When we add to these facts the research evidence that eyewitness memory is often inaccurate, we have a real potential for frequent misfires of the justice process, errors that cost money, time, and, in some cases, the freedom of an innocent person.

It is, however, decisions about eyewitness testimony, rather than the testimony itself, that lead to errors in the delivery of justice. They occur when a fact finder (a police officer, clinical interviewer, juror, or judge) believes an inaccurate witness or doubts an accurate one. As Wells (1985a) has noted, “if jurors and judges were able to discriminate meaningfully between accurate and inaccurate eyewitness testimony, our concerns about inaccurate testimony would be lessened considerably” (p. 45). In this chapter, I will be concerned with how fact finders appraise eyewitness reports. I will review research and lay some theoretical groundwork concerning how and how well people evaluate memory reports. What factors influence judgments of witness credibility and how valid are these judgments?