Interviewing witnesses: eliciting coarse-grain information

Eyewitnesses to crimes sometimes report inaccurate fine-grain details but fail to report accessible and potentially accurate coarse-grain details. We asked college students and community members (aged 17 to 62 years) who viewed a video of a simulated crime to answer interviewers’ questions at coarse- and fine-grained levels of detail and measured the quantity and accuracy of their responses. Three experiments (overall N = 219) also (a) provided comparative data for participants who were interviewed using the open-ended Self-Administered Interview (Gabbert, Hope, & Fisher, 2009) or one of two “report everything” open-ended procedures, (b) tested the efficacy of the procedure using both written and verbal interviews, and (c) examined the generality of the findings across different encoding stimuli which required variations in the types of cued recall questions asked. Coarse-grain reporting seldom occurred under the free recall interview conditions. Witnesses provided abundant coarse-grain details when required to respond to probes about specific details (i.e., cued recall forced report conditions)—without obvious cost to overall accuracy relative to accuracy of similar detail reported under free recall conditions—regardless of whether they responded on a written questionnaire or in a face-to-face individual interview. These experiments suggest that a procedure that requires cued recall forced reporting of coarse-grain detail may offer potential in certain investigative situations as an adjunct to the widely recommended open-ended forensic interviewing techniques.