Cost and benefit of a new instruction for the cognitive interview: the open depth instruction

Abstract

The quality and the quantity of information recalled by eyewitnesses during a criminal investigation is of crucial importance. To increase the volume of details recalled during an interview, the cognitive interview recommends using various retrieval strategies to enhance recall. We tested a new retrieval instruction, the open depth (OD) instruction. The efficacy of this new instruction was assessed with the number of unit of information and the accuracy rate. We also assessed the cost-and-benefit of this new instruction with measures of repetition. Students watched a video of a simulated robbery and participated later in face-to-face interviews. In Study 1 (N=60), the cognitive interview using the OD instruction increased recall compared to the interview using the change of perspective (CP) instruction, without affecting the accuracy rate. The redundancy rate was higher with the OD instruction than with the CP instruction. In Study 2 (N=40), the OD instruction generated more new information without affecting the accuracy rate than the interview using motivated recall (MR) instruction. The repeated information to new information ratio was lower with the OD instruction than with the MR instruction. The advantages of the OD instruction for investigative interviewing purposes are discussed.

Keywords:

• cognitive interview
• redundancy
• instruction
• interviewing
• witness/victim

Acknowledgements

This paper is an extract of Maïté Brunel's unpublished doctoral dissertation conducted at the Université Toulouse 2, France, under the supervision of the second author. The third author participated in the conduct, the analysis and the interpretation of Study 2. This research was also presented at the 2010 European Association of Psychology and Law Conference in Gothenburg, Sweden.

Notes

1. What is commonly called ‘standard’ police interview is the interview technique usually used by police officers. The ‘structured’ interview includes the social facilitative techniques of the cognitive interview minus the mnemonic components (Köhnken, Thurer, & Zoberbier, 1994).

2. Following the recommendation of two reviewers, we decided to change the original name of this instruction, the ‘peripheral focus’ instruction, to the ‘open depth’ instruction.

3. A variation of this instruction was recently tested: the guided peripheral focus instruction (Colomb & Ginet, 2011).

4. The OD instruction was principally thought to be used to generate an additional free recall during the same interview session. Although we could conceive a case where the witness had been previously interviewed thus, as a reviewer pointed out, it would also be possible to use this instruction for the first recall of an additional interview session.

5. The abbreviations CICP, CIOD and SI are used when referring to the whole interview. CP, OD and FR are used only when referring to each instruction separately.

6. Additional dependent variables were analyzed such as the novelty rate, the repetition rate, the exertion rate and the surplus rate; for a description and results see Brunel (2009).

7. As the pattern of results for the first recall attempt was similar to the results of the overall interview, they have not been presented but they can be obtained by contacting the second author.

8. The abbreviations CIMR and CIOD are used when referring to the whole interview. MR and OD are used only when referring to each instruction separately.