Co-witnesses’ effects on eyewitness memory:

The Misinformation Paradigm

Date & Time: 7th of January 1030 hours Chair: Kazuo Mori, Shinshu University

Contributors: Kazuo Mori, Shinshu University

Yuji Itoh, Keio UniversityFiona Gabbert, University of Aberdeen

Elizabeth F. Loftus, University of California, Irvine

Introduction:Three researchers will present their experimental findings of co-witness influences on memory using new experimental paradigms.Despite differences in their methods, similar findings have been obtained. Witnesses tended to conform to their co-witnesses and report what the co-witnesses had observed as if it had been observed by themselves. Following the presentations, Beth will discuss the main findings and implications of them.

A New Experimental Paradigm for

Collaborative Eyewitness Testimony Using a Presentation Trick

Kazuo MoriShinshu University, Nagano, Japan

kazmori@gipnc.shinshu-u.ac.jp

Wanted

The MORI technique: A new experimental procedure for research in memory distortion. Mori, 2003b)

Uses the polarization

properties of light.

Two different images presented on the same screen can be seen separately by two groups of viewers without them noticing that there are two different

overlapping images.

Projector B is tilted 90 degrees to make its polarized image perpendicular to Image A.

Outline of the event

• Fig.3 Two versions of basically the same event• A car pulls up in front of a female pedestrian. • The driver gets out of the car to ask her for directions. • While she explains the directions, another passenger sneaks out of the car to steal

something from her bag. • The pedestrian walks away without noticing the theft.

Three Differing Points • Color of the car: dark car vs.

white car

Fig.4 Three Differing Points in the Two Versions

• Clothes of the driver: parka with stripes vs. white shirt

• Direction of the pedestrian after the thievery: walking toward the viewer vs. walking away from the viewer

One or two weeks

Fig.5　 Experimental Schedule

Discussion

Pre-Discussion Report (Separate)

Post-Discussion Report(Unified)

Week-Later Report (Separate)

Presentation of the Event

Post-Discussion Report(Separate)

Ab

ou

t 20

to 2

5 m

inu

tes

Main Results

(Kanematsu et al.,1996/2003)

• No subjects noticed the presentation trick.

• No group failed to reach agreement even on the three differing points. – Witnesses would easily

change their opinion about what they had seen.

• There was no clear tendency concerning who conceded to whom.

• Even those who changed their original report had high confidence in their memory.– Confidence would not

insure the accuracy.• Discussion improved

memory performance in general.

■■■■■■■■■■■■■■■■■■■■

■■■■■■■■■■■

■■■

Absolutely Confident

Highly Confident

Rather Confident

Neutral

Not So Confident

Hardly Confident

Least Confident

■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■

■:Reported what they had seen correctly

■:Reported consciously what the other party had seen

■:Reported unconsciously what the other party had seen

■:Reported mutually what the other party had seen

Confidence Ratings

Fig.6 Distribution of Confidence Ratings and their Accuracy

Summary of Results of Experiments Using the MORI Technique

• Sex and gender comparison– No sex differences in

conformity

Fig.7

• Group size of witnesses– One always concedes to two– Fewer conformities in two vs.

two• Mother-child pairs

– Mothers not always dominant

• Animations– Easy to remember – Fewer conformities

• Pre-schoolers– Poorer memory performance– More conformities

0.00% 20.00% 40.00% 60.00% 80.00% 100.00%

1

Unconscious

Conscious

Effects of Group Size

(Mori & Mori, 2004)

Less frequent ‘Conscious agreements’ (■) in Two-vs-Two

Fig.8 Agreement in Week-Later Reports

More frequent ‘Conscious agreements’ (■) in Two-vs-One

No differences among ‘Unconscious agreements’ (■)

Mother-Child Pairs (Mori, 2003a)

No differences were found concerning whose opinions

were taken.

18

21

6

9

6

0

6

6

3

3

9

3

0%

20%

40%

60%

80%

100%

Car Driver Walk Total

Mothers’ Opinions

Children’s Opinions

Others

Fig.9　 Dominant Opinions for the Three Differing Points

No significant tendencies for choosing between original and agreed answers.

10

14

3

8

7

1

0%

20%

40%

60%

80%

100%

Mothers Children

Back to Originals

Maintain Agreed Answers

Other Choices

Fig.10　 Choices in Week-Later Reports

Animation: a new technique

• Events presented by an animated picture were much easier to remember than those by real pictures.

Fig.11

Fig.13 Better Recall inAnimated Picture Conditions

0

1020

3040

50

6070

8090

100

Pre-discussion

Post-discussion

One-week-later

Animation(Pairs)

Animation(Triads)

Real Picture

Fig.12

Fig.14 Fewer Frequency ofAdoption in Animation

Viewers(Å°Å°)

0

10

20

30

40

50

60

70

RealPicture

Pairs Triads

Fig.13

• Subjects made fewer adoptions of the other party’s opinions.

Preschoolers vs. Undergraduates

(Mori & Takahashi, 2004)

• Pre-schoolers showed poorer recall than undergraduates in general.

Mean Recall Scores at the Three Recall Periods

0

10

20

30

40

50

60

70

80

90

Pre-collaboration Collaboration Week-Later

Fig.14 Poorer Recall in Preschoolers

p<.01

• Pre-schoolers tended to conform more frequently than undergraduates in the Week-Later Reports.

Targetitems

Allitems

0

5

10

15

20

25

30

p<.05

Fig.15 More Frequent Conformity among Preschoolers

Ad j

us t

ed F

req u

e nc y

of

Co n

form

ity

References• Hirokawa,K.,Matsuno,E.,Mori,K.,& Ukita,J.(2003) The relationship between masculinity-femini

nity and suggestibility in an experimental collaborative eyewitness testimony. Submitted to Asian Journal of Social Psychology.

• Kanematsu,H.,Mori,K.,& Mori,H. (1996/2003) Memory distortion in eyewitness pairs who observed nonconforming events and discussed them. Ninchi-Kagaku (in Japanese, 1996); Journal of the Faculty of Education Shinshu University,109, 75-84, (2003).

• Mori,K.(2003a). “No, Mum. It was a white car”: What happens if mother and child dyads witness the same event differently? Poster presented at the 4th Tsukuba International Conference on Memory, Tsukuba, (March, 2003)

• Mori,K.(2003b). Surreptitiously projecting a different movie to two subsets of viewers. Behavior Research Methods, Instruments, and Computers, 35, 599-604.

• Mori,K. & Mori,H.(2004). Second-Order Effects of the Presence of Co-witnesses on Memory Conformity in Experimental Collaborative Eyewitness Testimony. Submitted to Journal of Applied Social Psychology.

• Mori,K. 、 & Takahashi, R. (2004). Pre-schoolers’ reports of conflicting points surreptitiously inserted into a co-witnessed event. Paper presented at the 5th Tsukuba International Conference on Memory, Tsukuba, (March, 2004)

Acknowledgments. This research was supported by the Grant-in-Aid from Japanese Ministry of Education, Culture, Sport, Science, and Technology (Grant No.16330139).

Wanted

Two Different Verbal Materials Are Presented Simultaneously

The fMORI Technique (Mori, 2004) A single projector can project two different items onto a single screen t

o be seen separately by two groups of viewers.

Projector (EPSON LP-700)

Component G and Components R&B are overlaid.

Component G and Components R&B are seen separately through polarizing sunglasses.

T

S

Merits and demerits of the two MORI Techniques

The original MORI• Full color movies

• Two DLP projectors are needed.

• Difficult to arrange the suitable position.

The fMORI• Monochrome, still pic

tures, or words

• Only one LCD projector is needed.

• Arrangement is not necessary.

Collaboratorsare

Wanted.If you want to use the MORI technique,

e-mail me: kazmori@shinshu-u.ac.jp