Eliciting new information from eyewitnesses via repeated interviews: How does it impact accuracy

and credibility?

Amina Memon

Royal Holloway, University of London

Geralda Odinot

University of Leiden

David LaRooy

University of Abertay

We know that.....

Witnesses may be questioned on multiple occasions over lengthy delays (LaRooy Katz, Malloy & Lamb, 2010).

That “different” information is often produced across repeat interviews raises concerns among legal professionals

Consistency and Accuracy: Impact onWitness Credibility

Judges and Legal scholars deem witness consistency to be one of the most important measures of witness credibility

Witness credibility is often attacked by highlighting inconsistencies in statements including the reporting of new previously unreported details.

Self-contradiction is believed to be a result of a defect in memory or honesty of a witness

Fisher, Brewer & Mitchell, 2009

In an applied setting We need to look carefully at what is

recalled and not just amount (Koriat and Goldsmith, 1994)

New information should not be viewed as inconsistent or contradictory or indicate that a witness is not credible or inaccurate (Gilbert & Fisher, 2006).

Lengthy delays The delays which occur during an

investigation may compromise the quality of the evidence that can be obtained from a witness

We could only sample short delays but we wanted to see if even a delay of 1 week would make a difference.

Research Questions How is eyewitness recall (quality and quantity)

influenced over repeat interviews influenced by:

Delay- forgetting increases over time so should a repeated interview be conducted as soon as possible?

Interview (Cognitive or Structured) across repeat interviews?

Method 107 college students Video event of stalker who follows victim

and enters her house One female interviewer fully trained in the

Structured (SI) and Cognitive Interview (CI) Each witness was interviewed twice

Interviewer Training

The interviewer underwent 2 day training in the Cognitive and Structured Interview methods with practice and feedback.

COGNITIVERapport & Ground RulesReport EverythingContext ReinstatementFree RecallQuestion phase

STRUCTUREDRapport & Ground RulesFree RecallQuestion phase

Immediate & 2 days

Delayed for 7 & 9 days

Condition 1 CI-CI

Condition 2 SI-SI

Condition 3 CI-CI

Condition 4 SI-SI

Results Number of Correct Details in the first interview The number of NEW unique details across the

two interviews

1. Interview type (CI or SI)

2. Interview timing (Early- Delayed for 7 days)

Number of correct details at interview 1

.000

10.000

20.000

30.000

40.000

50.000

60.000

70.000

80.000

CI SI

Early

Delayed

Number of correct details as a function of interview timing: Early (immediate and 2 days) versus delayed (2 and 7 days)

.0000

10.0000

20.0000

30.0000

40.0000

50.0000

60.0000

70.0000

80.0000

Early Delayed

Interview 1

Interview2

New (previously unreported) correct details by interview type and timing of interview

.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

CI SI

Repeated interviews

Early

Delayed

Note: most of these errors occurred during the questioning phase.

Total number of errors across the two interviews

0

5

10

15

20

25

CI SI

Repeated interview

Early

delayed

Results Next we will look to see if details (correct

and incorrect) were consistently reported across the two interviews

Number of correct details consistently reported across the two interviews

0

10

20

30

40

50

60

CI SI

Repeated interview

Early

delayed

New Incorrect details by interview type and interview timing (early/delayed)

.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

CI SI

Repeated interviews

Early

Delayed

Information gain from repeated testing

Finally we looked at the cumulative recall across the two interviews

We counted the repeated details only once and added any new previously unreported information.

Total number of unique details* across the two interviews (*total in first interview plus new items at time 2)

0

10

20

30

40

50

60

70

80

90

100

CI SI

Repeated interview

Early

delayed

Conclusions 1 Clear effects of early interview and repeated

testing- gain in new correct details with small increase in errors

CI advantage in correct details and consistent details- important for credibility

CI small increase in reporting of erroneous detail- there were fewer errors in the free recall phase most arose in the questioning sequence.

Conclusions 2 Benefits of Repeated interviews-increase in

the number of unique (cumulative) details Early interview advised but we need to

examine the effects of longer delays

New Meta-analysis of the Cognitive Interview

 http://www.pc.rhul.ac.uk/sites/rheg/

This research was funded by a European Union (FP6) grant