1. The effect of warning against conformity on memory accuracy after cooperative remembering Yuji Itoh, Satoshi Umeda, Jun Kawaguchi Keio University University of Nagoya Keio University University of Nagoya

2. The effect of warning against conformity on memory accuracy after cooperative remembering Yuji Itoh, Satoshi Umeda, Jun Kawaguchi Keio University University of Nagoya Keio University University of Nagoya

3. The effect of warning against conformity Yuji Itoh, Satoshi Umeda, Jun Kawaguchi Keio University University of Nagoya Keio University University of Nagoya

4. The effect of warning against conformity: Does it reduce the memory conformity effect? Yuji Itoh, Satoshi Umeda, Jun Kawaguchi Keio University University of Nagoya

5. The effect of warning against conformity: Does it reduce the memory conformity effect? Yuji Itoh, Satoshi Umeda, Jun Kawaguchi Keio University University of Nagoya

6. The effect of warning against conformity: Does it reduce the memory conformity effect? Yuji Itoh, Yuji Itoh, Keio University Keio University

7. The effect of warning against conformity: Does it reduce the memory conformity effect? Yuji Itoh & Mayumi Harada Keio University

8. The effect of warning against conformity: Does it reduce the memory conformity effect? Yuji Itoh & Mayumi Harada Keio University

9. INTRODUCTION Memory Conformity Effect Memory Conformity Effect Information from other people during collaborative remembering as misleading information Information from other people during collaborative remembering as misleading information Kanematsu, Mori, & Mori (1996) Kanematsu, Mori, & Mori (1996) Wright, Self, & Justice (2000) Wright, Self, & Justice (2000) Reduce or elimination of misinformation effect by source monitoring test Reduce or elimination of misinformation effect by source monitoring test Lindsay & Johnson (1989) Lindsay & Johnson (1989)

10. Does warning against conformity given after collaborative remembering reduce the memory conformity effect in later remembering? Does warning against conformity given after collaborative remembering reduce the memory conformity effect in later remembering? A preliminary experiment using MORI technique suggested some possibility. A preliminary experiment using MORI technique suggested some possibility. Examined the effect of warning against conformity. Examined the effect of warning against conformity.

11. ICI paradigm ICI paradigm comparison between BC responses and AC responses comparison between BC responses and AC responses independent rememberingBC collaborative rememberingCR independent rememberingAC

12. BC might strengthen memory for the witnessed event and/or source memory. BC might strengthen memory for the witnessed event and/or source memory. In many cases, there is no remembering attempt that corresponds to BC for real life eyewitnesses. In many cases, there is no remembering attempt that corresponds to BC for real life eyewitnesses. Examine the effect of warning to decrease memory conformity when there is no BC. Examine the effect of warning to decrease memory conformity when there is no BC.

13. Questions Does warning after collaborative remembering reduce memory conformity? Does warning after collaborative remembering reduce memory conformity? Is the effect of warning to decrease memory conformity smaller when participants have no chance to remember the event independently before collaborative remembering? Is the effect of warning to decrease memory conformity smaller when participants have no chance to remember the event independently before collaborative remembering?

14. METHOD Participants Participants 78 undergraduates (39 dyads) 78 undergraduates (39 dyads) Apparatus Apparatus MORI technique MORI technique Each participant in a dyad observed slightly different set of slides. Each participant in a dyad observed slightly different set of slides.

15. Materials Materials Sequences of slides that depict a criminal event Sequences of slides that depict a criminal event 26 slides X 2 26 slides X 2 Two sequences are similar to each other except 4 details. Two sequences are similar to each other except 4 details. A female thief’s behavior after she stole a purse A female thief’s behavior after she stole a purse The direction to which the pair of thieves went away The direction to which the pair of thieves went away Items the female thief possessed Items the female thief possessed Color of the male thief’s shirt Color of the male thief’s shirt

16. presentation of slide sequence BC recognition test C recognition test warning warned w BC 7 dyads unwarned w BC 7 dyads control w BC 7 dyads warned w/o BC 6 dyads unwarned w/o BC 6 dyads control w/o BC 6 dyads AC recognition test

17. Recognition items Recognition items Critical items: Questions on the details about which a dyad saw different scenes. Critical items: Questions on the details about which a dyad saw different scenes. 4 items 4 items Non-critical items: Questions on the details about which a dyad saw the same scene. Non-critical items: Questions on the details about which a dyad saw the same scene. 22 items 22 items

18. RESULT Change from BC to AC in with BC condition Change from BC to AC in with BC condition conformed: conformed: BCCRAC warned and unwarned xyxxx xyxyy controlxyxx

19. conformity ratio conformity ratio for critical and non-critical items separately for critical and non-critical items separately for each participant for each participant number of conformed items number of discrepancies in BC responses

20. Conformity ratio for w BC cond Non-critical items Non-critical items conformity ratio.06.45.13

21. Critical items Critical items conformity ratio.00.34.06

22. For both Non-critical and Critical items For both Non-critical and Critical items number of conformed items and conformity ratio was higher for number of conformed items and conformity ratio was higher for unwarned than control condition unwarned than control condition but not higher for but not higher for warned than control condition warned than control condition unwarned > warned = control unwarned > warned = control

23. To examine the effect of BC In without BC condition, we can’t calculate the conformity ratio. In without BC condition, we can’t calculate the conformity ratio. Numbers of correspondence in AC responses are an appropriate index of conformity. Numbers of correspondence in AC responses are an appropriate index of conformity.

24. Effect of BC Numbers of correspondence in AC Numbers of correspondence in AC Non-critical items Non-critical items

25. Critical items Critical items

26. DISCUSSION Collaborative remembering makes memory conformity in later independent remembering. Collaborative remembering makes memory conformity in later independent remembering. information from others as a source of misinformation effect information from others as a source of misinformation effect

27. Warning against conformity reduce this memory conformity effect Warning against conformity reduce this memory conformity effect if there is independent remembering attempt before collaborative remembering if there is independent remembering attempt before collaborative remembering

28. Non-critical items Critical items Non-critical items Critical items

29. Warning against conformity reduce this memory conformity effect Warning against conformity reduce this memory conformity effect if there is independent remembering attempt before collaborative remembering if there is independent remembering attempt before collaborative remembering if and only if? if and only if?

30. Non-critical items Critical items Non-critical items Critical items

31. Warning against conformity reduce this memory conformity effect Warning against conformity reduce this memory conformity effect if there is independent remembering attempt before collaborative remembering if there is independent remembering attempt before collaborative remembering if and only if? if and only if? probably… probably… We need more data! We need more data!

32. To compare w BC with w/o BC Conformity and responses in CR and AC Conformity and responses in CR and AC conformity and number of items with same AC responses conformity and number of items with same AC responses correlations are moderately high correlations are moderately high Non-critical items Critical items N. of conf. conf. ratio N. of conf. conf. ratio.42.57.68.70

33. conformity and change from discrepancy to correspondence conformity and change from discrepancy to correspondence For all cases where a pair of responses were not same in BC and same in AC, conformities were observed. For all cases where a pair of responses were not same in BC and same in AC, conformities were observed. There were a few cases where no such changes were observed whereas conformities were observed. There were a few cases where no such changes were observed whereas conformities were observed. Each member of a pair conformed to the other. Each member of a pair conformed to the other. BCCRAC xyxyx

34. Non-critical items warnedunwarnedcontrol changes16476 conformity17536 Critical items warnedunwarnedcontrol changes3160 conformity3170

35. Numbers of correspondence in BC responses are expected to be same for warned, unwarned, and control conditions. Numbers of correspondence in BC responses are expected to be same for warned, unwarned, and control conditions. the extent to which individuals’ memories for each item correspond in a dyad the extent to which individuals’ memories for each item correspond in a dyad Numbers of correspondence in AC should be an appropriate index of conformity. Numbers of correspondence in AC should be an appropriate index of conformity.