The use of ground rules in investigative interviews with children: A synthesis and call for research

• We review evidence on the efficacy of ground rules instruction in child interviews.
• A study space analysis shows that the “don't know” rule is the most widely studied.
• Findings do not delimit an age range wherein children benefit most from instruction.
• Future research should explore the cognitive prerequisites for ground rules benefits.

Guidelines for conducting investigative interviews with children often include instructions that explain the conversational rules of the interview. Despite the widespread and international use of such instructions (also referred to as “ground rules”), the body of research characterizing children's understanding of these rules and documenting the impact of instruction on memory reports is relatively small. We review the use of ground rules in investigative interviews, the developmental differences that likely underlie children's ability to make sense of these rules, and research pertaining to the effects of the ground rules commonly included in interview guidelines on the reports of 3- to 13-year-old children. We then present a study space analysis concerning the five ground rules reviewed: (a) a statement about interviewer naïveté regarding the target events, (b) instructions to tell the interviewer when a mistake has been made, (c) cautions that some questions may be repeated, and instructions to say (d) “I don't understand” and (e) “I don't know.” The results demonstrate obvious gaps in this body of literature, with only the “I don't know” ground rule having received significant attention. In addition to exploring how individual rules impact interview performance, we encourage more process-oriented studies that relate developmental differences in ground rules benefits to the cognitive processes that underlie rule understanding and implementation. Optimally, this research should identify the most suitable format and placement of instruction in interviews and broaden to more often include field studies of child witnesses.