The effect of pre-interview knowledge and instructions on interviewer memory

Skilled investigative interviewing is critical to ensuring that credible witness accounts are gathered in criminal investigations. The current study aimed to determine whether instructions to avoid suggestive questions and pre-interview knowledge influence both the quality of an interviewer's questioning strategy and the interviewer's memory for the witness' account after a 1-week delay in a laboratory study using lay student interviewers and witnesses. Results indicated that access to case details prior to the interview did not significantly influence the type or quality of questions asked within the interview itself but significantly influenced interviewers' memories for their interview 1 week later. Those who were blind to case information at the time of the interview had more accurate memories of their witness interviews than those who were correctly or incorrectly pre-informed. Instructions to avoid suggestive questions served to reduce suggestive questions, regardless of pre-interview knowledge. Taken together, these findings suggest that pre-interview preparation may influence investigative outcomes beyond the interview context and traditional measures of witness accuracy.