Unanticipated questions can yield unanticipated outcomes in investigative interviews

Asking unanticipated questions in investigative interviews can elicit differences in the verbal behaviour of truth-tellers and liars: When faced with unanticipated questions, liars give less detailed and consistent responses than truth-tellers. Do such differences in verbal behaviour lead to an improvement in the accuracy of interviewers’ veracity judgements? Two empirical studies evaluated the efficacy of the unanticipated questions technique. Experiment 1 compared two types of unanticipated questions (questions regarding the planning of a task and questions regarding the specific spatial and temporal details associated with the task), assessing the veracity judgements of interviewers and verbal content of interviewees’ responses. Experiment 2 assessed veracity judgements of independent observers. Overall, the results provide little support for the technique. For interviewers, unanticipated questions failed to improve veracity judgement accuracy above chance. Reality monitoring analysis revealed qualitatively distinct information in the responses to the two unanticipated question types, though little distinction between the responses of truth-tellers and liars. Accuracy for observers was greater when judging transcripts of unanticipated questions, and this effect was stronger for spatial and temporal questions than planning questions. The benefits of unanticipated questioning appear limited to post-interview situations. Furthermore, the type of unanticipated question affects both the type of information gathered and the ability to detect deceit.

在侦讯访谈（investigative interviews）中提出非预期提问（unanticipated questions），可引发诚实陈述者与说谎者的言语行为差异：当面对非预期提问时，说谎者的回答相较于诚实陈述者，细节更少且一致性更低。那么这类言语行为差异，是否能够提升访谈者对陈述真实性的判断准确率？本研究通过两项实证研究，评估了非预期提问方法的应用效能。实验1对比了两类非预期提问——分别为围绕任务规划的提问，以及与任务相关的具体时空细节提问，并同时评估了访谈者的真实性判断表现，以及受访对象回答的言语内容特征。实验2则针对独立观察员的真实性判断表现进行了评估。综合来看，实验结果未为该方法提供充分的有效性支撑。对于访谈者而言，非预期提问未能使其真实性判断准确率高于随机猜测水平。现实监控分析（reality monitoring analysis）结果显示，两类非预期提问所对应的回答信息存在质的差异，但诚实陈述者与说谎者的回答之间几乎无显著区分。当观察员对非预期提问的转录文本进行真实性判断时，其判断准确率更高；且相较于任务规划类提问，时空细节类提问的这一提升效应更为显著。非预期提问的应用益处似乎仅局限于访谈后场景。此外，非预期提问的类型，既会影响所采集信息的类型，也会影响说谎行为的识别能力。