Statement Validity Assessment Vrij: Chapter 8
What is Statement Validity Assesment?
A “verbal veracity assessment tool” Originated in Sweden (1963) as a method to
determine the credibility of child witnesses in sexual abuse cases
Credibility of children in sexual abuse cases is critical, especially when there are no corroborating witnesses or physical evidence
So…
Unlike non-verbal deception detection techniques, you are not looking for “tells” as to when a person is lying
Problems with child witness testimonies
Vrij cites Craig, 1995, stating estimates range between 6% to 60% that child witness statements about sexual abuse are inaccurate– Due to parental influence, outside pressure,
simple misidentification, or complete lies
Adults tend to mistrust statements made by children
History of SVA
Udo Undeutsch and the West German Supreme Court– Presented case of a 14-year-old alleged victim of
rape using a method called statement analysis– Court ruled that outside psychologists had more
and better resources to determine truthfulness than court “fact finders”
– 1955 – court requires use of psychological interviews and credibility assessments in disputed cases
History of SVA continued…
Undeutsch was the first to create a comprehensive list of criteria to assess credibility
In 1988, Kӧhnken and Steller refined the criteria and standardized it in to a formal assessment procedure– Called it Statement Validity Analysis (SVA)
History of SVA continued…
So…– The current SVA method wasn’t created until the
1980s, more than 30 years after the German courts looked in to statement analysis
– Until this point, no studies had been done analyzing the validity of SA or SVA
Four Stages of SVA
1. Case-file analysis 2. Semi-structured interview 3. Criteria-Based Content Analysis (CBCA) 4. Evaluation of CBCA with the Validity
Checklist
Stage 1: Case-File Analysis
Analysis of facts in a case Expert forms hypotheses about what
happened. Details from the analysis will help the expert focus on critical details later in the interview.
Stage 2: Semi-Structured Interview
What the Criteria-Based Content Analysis (Stage 3) will analyze
Child gives his/her account of the allegation Can be very difficult do to lack of verbal or
cognitive skills in young children– Also highly influenced by personality factors such
as anxiety or simple embarrassment
Skill and knowledge of interviewer is critical
Stage 2: Semi-Structured Interview continued…
Interviewer must have a strategy for eliciting as much detailed information as possible
Has to ask the right questions in the right way– Must avoid leading, yes or no, questions– Must get child (or adult for that matter) to tell story
without interviewer influence
Stage 2: Semi-Structured Interview, continued…
Proper kinds of questions/techniques:– Open-ended (e.g. “Tell me what happened.”)– Facilitative responses
“OK”, “mmhm”, head nods, etc
– Focused questions Focus on specific details or aspects of the event
Problematic questions:– Leading (e.g. “Was it your dad?”– Option-posing (e.g. “Was the man white or black?”)
Stage 3: Criteria-Based Content Analysis (CBCA)
Used on transcripts of the interviews Consists of 19 criteria judged on a three
point scale.– “0” if criteria is absent, “1” if criteria is present, “2”
if criteria is strongly present
Consists of four categories
Stage 3: CBCA – The Four Categories
1. General Characteristics
2. Specific Contents
3. Motivation-Related Contents
4. Offence-Specific Elements
Stage 3: CBCA – General Characteristics (1-3)
1. Logical Structure– Statement is coherent and logically consistent
2. Unstructured Production– Information is presented in non-chronological
order
3. Quality of Details– Statement is rich in details
Stage 3: CBCA – Specific Contents (4-13)
4. Contextual Embedding– Events are placed in time and location
5. Descriptions of Interactions– Statements contain information that interlinks the alleged
perpetrator and witness
6. Reproduction of Conversation– Specific dialogue, not summaries of what people said
7. Unexpected Complications During the Incident
Stage 3: CBCA – Specific Contents (4-13) Continued…
8. Unusual Details– Tattoos, stutters, individual quirks
9. Superfluous Details– Details that are non-essential to the allegation
10. Accurately Reported Details Misunderstood– Mentioning of details outside a person’s scope of
understanding
11. Related External Associations
Stage 3: CBCA – Specific Contents (4-13) Continued…
12. Accounts of Subjective Mental State– Description of a change in a subject’s feelings
during the incident
13. Attribution of Perpetrator’s Mental State– Witness describes perpetrator’s feelings
Stage 3: CBCA – Motivated-Related Contents (14-18)
14. Spontaneous Corrections 15. Admitting Lack of Memory 16. Raising Doubts About One’s Own
Testimony 17. Self-Deprecation 18. Pardoning the Perpetrator
Stage 3: CBCA – Details Characteristic of the Offence (19)
19. Offence-Specific Elements– Descriptions of elements that are known by
professionals to be typical of a crime
Stage 4: Evaluation of CBCA with the Validity Checklist
The CBCA score alone is not enough to determine if a person is being truthful
The examiner must also take into account other factors that could have affected the outcome– Leading by the interviewer, outside influences,
witness’s cognitive abilities, etc…
The CBCA is NOT a standardized test
Stage 4: Evaluation of CBCA with the Validity Checklist, continued…
Attempts to standardize the CBCA results through an 11 point checklist
Allows the examiner to consider alternative reasons for CBCA outcomes
As these alternative reasons are rejected, the CBCA results become stronger (in the assumption that the score represents the veracity of the statement)
Stage 4: Evaluation of CBCA with the Validity Checklist, continued…
The Four Stages:– 1. Psychological Characteristics– 2. Interview Characteristics– 3. Motivation– 4. Investigative Questions
Stage 4: Evaluation of CBCA with the Validity Checklist – Psych Characteristics
1. Inappropriateness of Language and Knowledge
2. Inappropriateness of Affect
3. Susceptibility to Suggestion
Stage 4: Evaluation of CBCA with the Validity Checklist – Interview Characteristics
4. Suggestive, Leading, or Coercive Interviewing
5. Overall Inadequacy of the Interview
Stage 4: Evaluation of CBCA with the Validity Checklist – Motivation
6. Questionable Motives to Report– Both for witness and other parties involved
7. Questionable Context of the Original Disclosure or Report
8. Pressures to Report Falsely
Stage 4: Evaluation of CBCA with the Validity Checklist – Investigative Questions
9. Inconsistency with the Laws of Nature
10. Inconsistency with Other Statements
11. Inconsistency with Other Evidence
SVA – Issues
Effectiveness of individual criteria in CBCA Effectiveness of Validity Checklist Differences between laboratory and field
studies Detection rates and false-positives Countermeasures Applicability to adults? The Daubert Standard
CBCA – Issues
Not all statements are equally effective– A claim by a young child with less detail will be
scored lower on the CBCA scale than that of an older child or adult
Not all criteria are created equal– Generally, the criteria in groups 1 and 2 are the
most effective at distinguishing truth-tellers from liars
CBCA – Inter-Rater Reliability
Are CBCA scores found by one rater close to those of a second, independent rater?– Good for most criteria, except unstructured
production and spontaneous corrections– Overall score agreement is higher than on
individual criteria
Vrij’s Literature Review
Laboratory vs. Field studies– Deficiencies for one type are the other’s strengths
Lab – Not realistic, often based off observation of a video Field – “Ground truth” cannot always be established, methods
of finding it are not always consistent– In field studies, low quality statements are less likely to
obtain a truthful diagnosis or a conviction/confession, even if true
– High CBCA scores on false claims can lead to false-confessions or convictions
– Therefore, relationship between CBCA scores and convictions or confessions may not be accurate
Esplin et al., (1988)
Field study CBCA scored on 0-2 scale (range of scores
could be 0-38)– Confirmed statement average = 24.8– Doubtful statement average = 3.6
Differences between groups found in 16/19 criteria
However, there are criticisms…
CBCA results from other studies
Boychuck (1991) – 13/19 Lamb et al. (1997b)* – 5/14
– Plausible average = 6.74– Implausible average = 4.85
Parker & Brown (2000) – 6/18 Rassin & van der Sleen (2005) – 2/5 Craig et al. (1999)*
– Confirmed average = 7.2– Doubtful average = 5.7
* used a 0-1 pt scale on CBCA
Critical Difference to Non-verbal Studies:
All results found were in the expected direction, supporting the Undeutsch Hypothesis– Results in non-verbal studies are highly erratic– You may find non-verbal cues within individuals,
but between groups these do not exist
CBCA – Lab Studies
Difficult to create realistic situations Accuracy rates ranged from 54% to 90%
– Average rates for truths = 70.81%– Average rates for lies = 71.12%– Rates did not differ between children, adults,
witnesses, victims, or suspects
CBCA – Lab Studies, continued…
Serious methodological problems:– Different situations used– Different analysis methods used– Different amounts of training for raters– Some studies do not use the Validity Checklist
and base diagnoses purely upon the CBCA
CBCA – Lab Studies, continued…
But some important results remain– For the most part, all differences found were in
the correct direction, once again supporting Undeutsch
– Some individual criteria are more effective than others
Support percentages (differences found / studies investigated)
– Range from 76% (Criteria 3) to 0% (Criteria 17)
CBCA – Lab Studies, continued…
Other effective criteria:– 4. Contextual embeddings– 6. Reproductions of conversations– 8. Unusual details
Least effective:– 14-18 – Motivational Criteria– 17. Self deprecation actually occurred less in truth
tellers in two studies
CBCA – Classifications
1. Discriminate (statistical) analysis is the most common method
2. Rater makes own truth/lie classification– Computer analysis better at detecting lies
80% vs. 60% for human raters
– People better at detecting truths 80% vs. 53% for computers
3. General decision rules– E.G. Criteria 1-5, plus two others
Reviewing the Validity Checklist
Focuses on three things:– 1. Age of interviewee
Highly affects cognitive abilities Older age correlates with higher CBCA scores
– 2. Interviewer’s style Open-ended questions are most effective The “Cognitive Interview”
– 3. Coaching of interviewee Countermeasures
– Training of subject to include CBCA criteria in their statement– Easily defeat the CBCA analysis (only 27% of coached liars
caught)
What the lay-person believes…
Generally correct about number of details (Criterion 3) and descriptions of interactions (5)
Generally believe liars include more contextual embeddings (Criterion 4), unusual details (8), and superfluous details (9) in stories
Overall, the lay-person’s view differs somewhat from the experts’ view
– This, potentially, is a good thing
Problems with the Validity Checklist
Difficulty in identifying issues– Coaching by an adult is hard to discover
Difficulty in measuring issues– E.g. susceptibility to suggestion
Difficulty in determining impact of issues– The validity checklist is much more subjective and
less formalized than the CBCA– It is therefore harder to study
Vrij’s specific problems with VC
Issue 2 – Inappropriateness of Affect– Cites research that suggests there are two main psychological
reactions to a rape 1. Expressed style 2. Numbed style
Issue 10 – Inconsistencies between statements– Human memory is not perfect, details can be unintentional– A practiced lie will not contain as many inconsistencies
Issue 9 and 11 (Consistency with laws of nature, consistency with other evidence)
– Children’s scope of understanding often include fantasies and other things not in agreement with natural laws
– Sometimes, even in a true allegation, no other evidence can be found
Vrij’s specific problems with VC, continued…
Embedded false statements are difficult to detect
False memories
The Daubert Standard
Daubert vs. Merrel Dow Pharmaceuticals, Inc. (1993)– Set standards for the inclusion of expert witness
testimony in court cases in the United states– Consists of 5 criteria that must be met for
evidence to be admissible in court
The Daubert Standard, continued…
1. Is the scientific hypothesis testable? 2. Has the proposition been tested? 3. Is there a known error rate? 4. Has the hypothesis and/or technique been
subjected to peer review and publication? 5. Is the theory upon which the hypothesis
and/or technique based generally accepted in the appropriate scientific community?
So, what about SVA?
CBCA Lab
CBCA Field
Validity Checklist
SVA
1. Is the scientific hypothesis testable?
Yes Problematic Problematic Problematic
2. Has the proposition been tested?
Yes No No No
3. Is there a known error rate?
Yes, too high No No No
4. Has the hypothesis been subjected to peer review/publication?
Yes Yes No No
5. Is the theory based on generally accepted principles?
Unknown Unknown Unknown Unknown
Error rates
Refer to subjects that are classified incorrectly– Truth tellers classified as liars, and vice-versa
Error rate for CBCA judgments made in laboratory research is nearly 30% for both truths and lies– This is EXTREMELY high
Overall evaluation of SVA
While results from research on SVA strongly support the Undeutsch Hypothesis, SVA does not meet the requirements of the five criteria established by the Daubert Standard
70% correct classification is OK 30% error rate is much too high for a valid test Certain criteria in the CBCA appear to be highly
effective at discriminating truth tellers from liars Other criteria are wholly ineffective