From the Pigeon Lab to the Courtroom

The task of detecting the presence or absence of a stimulus based on a diagnostic evidence variable is a pervasive one. It arises in basic experimental circumstances, such as a pigeon making a decision about whether or not a stimulus was presented 10 seconds ago, as well as in applied circumstances, such as a witness making a decision about whether or not a suspect is the guilty perpetrator. Understanding how to properly conceptualize and analyze performance on a signal-detection task like that is nontrivial, and advances in this area have come mainly from experimental psychologists studying performance on basic memory and perception tasks. One illustrative example from the pigeon memory literature is considered here in some detail. Unfortunately, lessons learned by basic experimental psychologists (e.g., the value of using signal-detection theory to guide thinking, appreciating the distinction between discriminability and response bias, understanding the utility of receiver operating characteristic analysis, etc.), while having a major impact on applied fields such as diagnostic medicine, have not always been fully appreciated by applied psychologists working on issues pertaining to eyewitness misidentification. In this regard, signal-detection-based analyses can greatly enhance our understanding of important applied issues such as (a) the diagnostic accuracy of different police lineup procedures and (b) the relationship between eyewitness confidence and accuracy. The application of signal-detection theory to issues like these can reverse what many believe to be true about eyewitness identifications made from police lineups.