Transcript Fisher - iIIRG

Repeated interviewing of
witnesses and suspects
Ronald Fisher
Florida International University (Miami, U.S.A.)
iIIRG
(Dundee, Scotlant)
June 1, 2011
Accuracy rate per response
category (Gilbert & Fisher)
Time 1
Consistent
Forgotten
Reminiscent
Contradictory
.95
.93
-.62
Time 2
.95
-.87
.35
Legal Challenges:
Judge’s instructions
Florida Standard Jury Instructions in Criminal Cases,
1987,# 204, sub-para 8:…
“Did the witness at some other time make a
statement that is inconsistent with the
testimony he gave in court?”
Legal Challenges:
Recommended cross-examination
Bailey & Rothblatt (1971, p. 177):
“Capitalize on these conflicts. This is the most
effective way of discrediting [the witness’ s]
entire testimony.”
Glissan (1991, p.108):
“A true inconsistency can effectively destroy a
witness, and sometimes a whole case…If you
find a true inconsistency, or if you can
manufacture one, then use the deposition of
previous evidence to sheet it home.”
Poets know best
• Ralph Waldo Emerson:
• “Foolish consistency is the hobgoblin of
small minds.”
Multiple interviewing
• Most witnesses are interviewed repeatedly
• Relatively little research, however, on
multiple interviewing
What do we gain from
multiple interviewing?
• Opportunity to collect new information
• Opportunity to compare responses across
interviews
Collect New Information
• How often is new information generated
on a second interview (not collected on the
first): reminiscence?
• How accurate is reminiscent information?
Frequency of Reminiscence
• Gilbert & Fisher (2006)
• Procedure:
– See video, T1 (immed), T2 (2 days)
– Free Recall or Guided Recall
• Results: 189/192 show reminiscence
(others: Yuille & Turtle; Gabbert, et al)
• Mean number of reminiscences: 8.19
• Reminiscence is common experience
Accuracy of Reminiscence
• Accuracy rate of reminiscence .87
• Comparable results reported by others,
e.g., LaRooy et al.
• Conclusion – repeated testing is very likely
to generate new, accurate information – as
long as questions are open-ended
Goal
• To test the assumption that inconsistency
is an indicator of a weak memory or
deception.
• How valid is this assumption?
Overview
• Separate for inferences about memory
and deception.
• To show that people do rely on
inconsistency to infer about memory
accuracy and deception.
• Q? In fact, is inconsistency a good
predictor of memory accuracy and
deception?
• Sometimes.
Beliefs about Inconsistency
• Sign of a weak memory
• Sign of deception
People are swayed by these
inconsistencies
• Surveys:
– College Students (Brewer, Potter, Fisher, Bond, & Luszcz,
1999)
– Police, prosecutors, & defenders (Potter & Brewer,
1999)
• Experimental jury simulations
– Berman, Narby, & Cutler (1995)
– Brewer & Hupfeld (2004)
Legal Challenges:
Recommended cross-examination
Bailey & Rothblatt (1971, p. 177):
“Capitalize on these conflicts. This is the most
effective way of discrediting [the witness’ s]
entire testimony.”
Glissan (1991, p.108):
“A true inconsistency can effectively destroy a
witness, and sometimes a whole case…If you
find a true inconsistency, or if you can
manufacture one, then use the deposition of
previous evidence to sheet it home.”
Legal Challenges:
Judge’s instructions
Florida Standard Jury Instructions in Criminal Cases,
1987,# 204, sub-para 8:…
“Did the witness at some other time make a
statement that is inconsistent with the
testimony he gave in court?”
Attorneys’ vs. Researchers’
Goals
• Attorneys : to convince jurors or judges
that their side of the argument is correct.
• Scientists: to find out the truth and to
explain it.
Part I: Inconsistency as a
indicator of Memory Accuracy
Scientific Research on
Inconsistency
• Prior to 1970: very few studies
– Difficult to conduct (resource demanding)
– Memory theories about single recollections
– Exceptions (Erdelyi; Payne)
Recent Studies
• Naturalistic Studies
– Flashbulb memories (e.g., Pezdek)
– Holocaust survivors (Wagenaar & Groenweg)
– Epidemiological/Health (Fisher, et al)
• General Findings: some inconsistency
• Limitations: cannot measure accuracy
• Need laboratory studies to measure
accuracy
“Blended” experiments
• 19 Experiments
Fisher & Cutler (1996), Brewer et al (1999), Patterson & Fisher (2005); Gilbert & Fisher (2006);
Mitchell, Haw, & Fisher (2003); Fisher & Hazel (in preparation)
• Method:
– Event: videotape or live event
– Two tests (T1 & T2):
• T1 is immediate or after a few hours
• T2 is a few days or one or two weeks later
– Test questions: open-ended or closed (cued recall)
– T1/T2 cue similarity: same or different, e.g.,
temporal/temporal (same) or temporal/spatial (diff.)
Witness Recall at Time 1 & Time 2
T1: ….tall, hat, jacket, scar, red hair
T2:…..tall, hat, jacket, ……, bald,…. belt
Consistent: T1 + T2
Forgetting: T1 only
**Contradiction: T1 + T2 different
**Reminiscence: T2 only
Measuring Accuracy
• Accuracy rate =
# correct___
total # responses
• Calculate separately for each of the 4
response categories:
– Consistent
– Reminiscent
– Forgotten
– Contradictory
Measuring Consistency
• Consistenct rate =
# consistent__
total # responses
• Calculate separately for each of the 4
response categories
Three Corollaries of Belief
(Inconsistency = Inaccurate)
1. Inconsistent statements are inaccurate
2. Witness who make more inconsistent
statements are less accurate
3. Consistency and accuracy reflect one,
common, underlying process
Corollary # 1:
Inconsistent statements are
inaccurate
• To examine accuracy of 4 kinds of
statement:
• Consistent
• Forgotten
• Reminiscent
• Contradictory
Accuracy rate per response
category (Gilbert & Fisher)
Time 1
Consistent
Forgotten
Reminiscent
Contradictory
.95
.93
-.62
Time 2
.95
-.87
.35
Conclusion # 1
• Inconsistent statements are less accurate,
but we should distinguish between
different forms of inconsistency
• Reminiscent statements are still generally
(.87)
• Only contradictory statements are much
less accurate (.62 @ T2; and .35 @ T2)
Corollary # 2:
Inconsistent witnesses are
inaccurate
• To examine the correlation between
overall consistency and overall accuracy
(across witnesses)
Correlations between consistency
and overall accuracy (Gilbert & Fisher)
• Proportion contradictions: -.17
(non-significant)
• Proportion reminiscence:
(non-significant)
.03
• Similar pattern (small, non-significant
correlations) in other experiments
Conclusion # 2
• Inconsistent witnesses are only minimally
less accurate than consistent witnesses.
Puzzling Finding
• Contradictory statements are much less
accurate than consistent statements, but…
• inconsistent witnesses are only minimally
less accurate than (or the same as)
inconsistent witnesses
Solution to puzzle:
Items are processed independently
• Accuracy of recalling one set of items
(e.g., car) does not predict accuracy of
recalling another set of items (e.g.,
perpetrator)
Support for Independence
explanation
• Examine categories of information (e.g.,
car, perpetrator, setting).
• Examine inter-category correlations.
• Across 8 experiments, mean intercategory correlation = .11 (Brewer, et al.1999; Mitchell,
Haw & Fisher, 2003)
Implications of Independence
for courtroom and investigation
• Cannot challenge an entire witness’s
testimony, because he/she recalls some
items incorrectly.
• Can challenge only those individual
statements that we believe are incorrect
(e.g. contradiction).
Corollary # 3
• Consistency and accuracy reflect one,
common underlying process
Test Logic
• Do experimental manipulations have the
same or different effects on consistency
and accuracy? (Experimental dissociation)
• Same effects  one underlying process
Different effects  multiple underlying
processes
Experimental Results
• Some manipulations have the same
effects on consistency and accuracy, e.g.,
question format (open-ended vs. closed)
• Some manipulations have different effects
on consistency and accuracy, e.g. delay:
decreases accuracy but increases
consistency
Conclusions
• Some common elements -- but almost all
measures have some common elements.
• Some processes influence one measure
but not the other.
• Ultimate: Cannot reflexively interpret
inconsistency to indicate accuracy
A Framework for Understanding
Inconsistency
• Something must change from T1 to T2,
but what?
Candidates for Change
• Mental representation: knowledge base
• Retrieval processes: questions, interviewers
• Metacognition: monitoring one’s knowledge
Part 2: Inconsistency as an
indicator of deception
Two Approaches
1. What do people believe?
2. Is this belief valid? What is the truth?
Beliefs about Inconsistency as
an indicator of deception:
Real-world assessments
• Training agencies
• Interrogation manuals
• Surveys of police & judges
Beliefs about Inconsistency as
an indicator of deception:
Laboratory Studies
• Self-assessments
• Experimental manipulations
Consistency Heuristic
• Everyone believes that inconsistent
reports are grounds for doubting one’s
veracity.
How valid is the “consistency
heuristic”?
• Scientific, controlled studies
• Advantage of scientific, controlled
experiments: We know who is, in fact,
lying and who is telling the truth.
Scientific Research on
Consistency and Deception
• Relatively little research
• Research is resource-demanding
• Multiple testing
• Compare answers across tests
• Two laboratories: Granhag/Stromwall
Vrij/Fisher
Typical Laboratory Study
• Truth-tellers engage in an activity; liars do
not do the activity, but are asked to
convince an interviewer that they did.
• Interviewed/Tested twice (Int-1, Int-2)
– Interval varies from hours to days
– Interviewed individually or in pairs
• Compare their answers (consistency)
– Within respondents (Int-1 and Int-2)
– Across respondents (Resp # 1 and Resp # 2)
Two Patterns of Results
• Sometimes liars are as inconsistent (or
even less) as truth-tellers
(Granhag/Stromwall)
• Sometimes liars are more inconsistent
than truth-tellers (Vrij/Fisher)
Differences between
Granhag/Stromwall &
Vrij/Fisher
• Preparation for Interview: G/S vs. V/F
• Questions asked at interview (anticipated
or not): G/S vs. V/F
• Similarity of questions at Int-1 and Int-2:
G/S vs. V/F
Preparation for Interview
• Liars rehearse their story; truth-tellers do
not
• Liars are prepared to give a narrative
Liars Prepare: Evidence
• Observe liars and truth-tellers before being
interviewed
– Secondary task—catching liars with cartoons:
Cahill + Fisher
– Videotape preparing for interview shown to
observers (lie detectors): Cahill + Fisher
Prepared for Anticipated
Questions
• Liars are prepared to answer typical
questions: “What happened?”
• Liars can give same answers on two
different interviews, if they are prepared
(they anticipate the questions)
• G/S: anticipated Q: “What happened?”
F/V: unanticipated Qs “Location of waiter?”
Strategic Differences
• Liars (be convincing, i.e. consistent) vs.
Truth-tellers (be informative)
• Liars: Repeat vs. Reconstruct (Granhag/Stromwall)
• Implications for Question Similarity
between Int-1 and Int-2
Similarity of Questions
at Int-1 and Int-2
• Similar questions facilitate repeating
earlier answer (consistent responding).
• Different questions yield more
inconsistency, but mainly for liars: Verbal
and pictorial (sketch) reports (Vrij et al; Leins et al)
Leveraging Liars’ strategies
(consistent) to detect deception
• Different strategies
– Liars: to be consistent
– Truth-tellers: to provide information
• Different strategies yield different
behaviors in repeated testing: To provide
new information (truth-tellers) or not
(liars)? (Pludwinski)
– Converging results: individuals and pairs
Summary of Deception
Research
• Liars are consistent only if they can
1. prepare for and anticipate the interviewer’s
questions
2. remember their earlier (Int-1) answers
Interviewing Strategy to
“produce” inconsistency in liars
• Think about how liars might prepare for an
interview, and ask unanticipated questions
• Ask different questions across interviews
Overview of Inconsistency
Research
• No simple rule to infer whether
inconsistent respondents
– have generally poor memories
– are deceptive or truthful
• Behavioral patterns are complex
Approaches to complex patterns
1. Abandon reliance on inconsistency.
Limited utility
a. sometimes inconsistency is diagnostic
b. we must rely on some cues; what would
substitute for inconsistency?
Preferable approach
1. Better to understand the nature of
inconsistency, when it is and when it is
not an indicator of poor memory and
deception.
a. Here, hinted at some cognitive and social
approaches
b. Researchers and practitioners to develop
these and other ideas more thoroughly.
Questions & Comments
• Thank you!