Lauren Wysman , B.A. ( Hons .) Stephanie Fisico , M.A. Alan Scoboria , Ph.D.

1. The implications of instructions and of time delay for the use of “don’t know” responding in interviews. Lauren Wysman, B.A. (Hons.) Stephanie Fisico, M.A. Alan Scoboria, Ph.D. University of Windsor, Ontario, Canada

2. Investigative Interviewers • Trade off in goals: most accurate information vs. most complete accounts.

3. Dilemmas • Accuracy vs. output • Quantity vs. quality • “Don’t know” (DK) responses • How to deal with them in interviews

4. Don’t know (DK) Responding • DK responses • Complex • Resist interviewer pressure • Resist speculation (Poole & White, 1991) • Accurate when information is not present (Roebers & Fernandez, 2002) • Strategic regulation of memory – opt out strategy (Koriat & Goldsmith, 1996)

5. Research Program • Encouragement to use DK • DK clarification • Time delays

6. Question Types • Answerable vs. unanswerable

7. Research Program • Encouragement to use DK • Pre-interview • I am going to ask you a series of questions about the video you saw. Please answer every question to the best of your ability. Because I am interested in obtaining the most accurate information that you may remember, you should respond “I don’t know” as frequently as needed. This is preferable to providing an answer when you do not actually remember.

8. Research Program • Discouraged from using DK • I am going to ask you a series of questions about the video you saw. Please answer every question to the best of your ability. Because I am interested in obtaining any and all information that you remember, you should respond “I don’t know” only if you absolutely must. This is preferable to answering that you do not remember. • Control • I am going to ask you a series of questions about the video you saw. Please answer every question to the best of your ability.

9. Research Program • Encouragement (in Fisico & Scoboria, 2011, in submission) leads to more DK responses • Not merely a response set: • Avoided making errors to answerable and unanswerable questions • Made fewer errors overall

10. Research Program • DK clarification • Post questioning • Information not in video (NIV) • Information was present but cannot be recalled (Present, Not Remembered; PNR) • Interviewee really doesn’t know (True Don’t Know; TDK) (Scoboria et al., 2008).

11. Past Study (without delay) • 78 undergraduate students • Use more DK when encouraged • Does not impact memory for event – clarified accurately • Resist unanswerable questions • Fewer errors • Learn about what they did and did not see. • Recoding leads to changes in accuracy.

12. Research Program • Time delays • Have examined efficacy of clarification and encouragement to use DK. • Interviewed appx. 30 minutes after encoding. • New study: seven day delay from watching crime film to the interview.

13. Present StudyProcedure • Time 1 • Non-violent crime video • Time 2 (seven days later): • DK instructions • Questioning • 10 answerable and 10 unanswerable • Clarify any DK responses • Used normed questions and a standardized coding manual • Answers transcribed verbatim by interviewer • No feedback given by interviewer.

14. Measured Variables • Number of responses • DKs • Correct responses • Errors • Output • Accuracy • # of Correct Responses / Output

15. Current study: 7 day delay • 76 undergraduate students • Initial responses • Answerable questions • Encouraged group had more DKs and fewer errors. • Overall, more accurate. • Control group fared better than Discouraged.

16. Current study: 7 day delay • Initial responses • Unanswerable questions • DK • Encouraged > Control > Discouraged • Errors • Discouraged and Control > Encouraged

17. Current study: 7 day delay • Post-DK clarification Recall: PNR: Present Not Remembered NIV: Not in Video TDK: True Don’t Know

18. Current study: 7 day delayPre/post clarification, unanswerable • Increase in output. • Increase in accuracy.

19. To conclude • Without time delay • Encouraged demonstrate better sensitivity to contents of video. • Clarification increases output; accuracy for unanswerable questions. • With time delay • Encouraged group does better before clarification. • Encouraged group • Higher accuracy (answerable and unanswerable) • More DKs clarified appropriately

20. To conclude • Over time, memory for events is expected to degrade. • Efficacy of encouraging DK and clarifying what is meant by DK hold up with a one-week long delay. • Avoidance of errors with gains in potentially useful information. • Still filtering out unanswerable questions after one week.

21. To conclude • However, we do not account for what occurs in the span of that week. • Interactions with other witnesses? • Confirmatory feedback? • Other poor interviews? • Generalizing to applied settings

22. To conclude • May be challenging to avoid unanswerable questions. • Encouragement and clarification = protection without negatively affecting available information.

23. Acknowledgements • Many thanks to Seda Suner, Stephanie Oneshuck, Dwayne Barris, and Omari Hickson for help in data collection. • We also thank the Natural Science and Engineering Research Council of Canada (NSERC) for funding this project.