Everyday situations require individuals to understand another person's level of confidence in his/her memory. For example, when a spouse says, "I'm pretty sure I locked the door" do you interpret that statement as indicating that you should double check the lock or not. Interpretation of such expressions of confidence present important cognitive challenges and can be influenced by a number of different factors. The cognitive biases that can influence these interpretations of confidence and the approaches to expressing confidence that might limit the impact of these biases are important areas of research with wide-ranging applications. The current project examines these factors in the context of eyewitness identification. When an eyewitness identifies someone from a lineup and states, "I'm pretty sure it's him," how do we know that police, jurors and others will interpret this expression of confidence in the way that it was intended? While a large literature exists on eyewitness confidence and (a) its relationship with identification accuracy, (b) its influence on jurors, and (c) its vulnerability to influence from post-identification feedback, very little is known about how other people understand the verbal expressions of eyewitness confidence. The outcomes of this project in terms of a more thorough understanding of the cognitive factors that influence interpretations of confidence are anticipated to have broad implications for settings, such as judicial proceedings, that involve the interpretation of another person's confidence.
This project investigates how people understand an eyewitness's verbal expression of confidence in the accuracy of his/her identification from a lineup of faces. There are three goals: first, the project examines how the particular content of an eyewitness's justification for his/her level of confidence (e.g., "I'm pretty certain it's him because I remember his chin") influences how people understand the eyewitness's confidence-statement. Second, there are a variety of cognitive biases that cause individuals to misinterpret the verbal expressions of certainty. For example, mounting research on the 'outcome-severity bias' shows that the identical verbal probability phrase (e.g., "it is somewhat likely") is interpreted as denoting a higher numerical likelihood when that phrase refers to more severe events rather than less severe events. The project considers whether eyewitness expressions of confidence are vulnerable to misunderstandings that are caused by the same kinds of cognitive biases. Third, the proposed experiments investigate whether the harmful influence of these cognitive biases can be mitigated by expressing confidence numerically instead of verbally. Overall, the project will fill a profound lack of knowledge about how people understand eyewitness confidence in a lineup identification. Moreover, the knowledge that verbal expressions of certainty are vulnerable to misinterpretations may: (a) guide police to obtain a numerical estimate of certainty from eyewitnesses; and (b) alert police, lawyers, judges and jurors to potential pitfalls about interpreting verbal expressions of certainty.
