The impact of psychological expert testimony in child sexual abuse cases

244 Pages·2011·4.4 MB·English

by  Crowley, Michael

UNIVERSITY
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TASMANIA
LIBRARY
The impact of
psychological expert testimony
in child sexual abuse cases
The impact of
psychological expert testimony
in child sexual abuse cases
by
1(.1,"1'1
Michael J. Crowley, B.A. (Hons.)
in the Departmentof Psychology
Submitted in partial fulfilment of the requirements
for the degree of Doctor of Philosophy (Clinical Psychology)
University of Tasmania
September, 1994
I certify that this thesis contains no material which has been accepted for the
award of any other degree or diploma in any tertiary institution, and that to the best
of my knowledge and belief, the thesis contains no material previously published or
written by another person, except where due reference is made in the text of the
thesis.
This thesis may be made available for loan. Copying of any part of this thesis is
prohibited for two years from the date this statement was signed; after that time
limited copying is permitted in accordance with the Copyright Act 1968.
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Signed
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Date
i i
ABSTRACT
While the admissibility of psychological expert testimony varies from one
common law country to another, evidentiary analyses dealing with the impactof such
testimony are invariably opinion-based and lack empirical support. Predictions
from theoretical models of communication/persuasion processes suggest that
psychological experttestimonyin childsexual abuse cases maybe given considerable
weight by jurors, but the experimental literature investigating the impact of such
testimony is scant.
This thesis reports four experimentsdesigned to investigate the juridical impact
of psychological expert testimony in a simulated child sexual abuse case, using
gender-balanced juries throughout. In the first study, presence or absence of a
psychologist's generalised testimony concerning children's cognitive abilities was
varied across three ages of child victim/witness. Subjects viewing the expert
testimony rated the child higher on memory ability, resistance to suggestion and
reality monitoring ability and gave higher ratings of defendant guilt.
In the second experiment, the sameexperttestimonywas presented by male and
female experts in either an adversarial or nonadversarial role. Significant
interaction effects indicated that, for the male expert only, ratings of the dependent
variables were significantly lower in the adversarial role.
The third experiment investigatedwhether expert testimonypresented before and
after the child's testimony is differentially utilized. Ratings of the child-based
variables and verdict ratingsdid notdiffer as a function of the sequenceof testimony,
but regardless of temporal order, presence of expert testimony led to significantly
higher child-based ratingsthan the absence of suchtestimony.
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In the fourth experiment, the differential impact of three types of expert
testimony were studied; testimony concerning children's general cognitive abilities,
testimony concerning characteristic behavioural reactions to sexual abuse, and
testimony assessing the validity of the child's statement. The quality of the child's
statement was varied, using content-based criteria. Subjects viewing the cognitive
abilities testimony rated the child higher on memory, resistance to suggestion and
reality monitoring, but there were no significant differences on verdicts by type of
testimony. Those who viewed the child's enhancedstatement gave higher ratings of
defendant guilt on the aggravated sexual assault charge. Results indicated greater
acceptance but less scrutiny of nonadversarial expert testimony.
In all four studies, the prime predictor of child credibility and verdict ratings
were the jurors' perceptions of whether the child had misinterpreted the defendant's
actions. Juror gender effects were also consistent in all studies, with females more
likely to rate the child's credibility higher and to find the defendant guilty.
In general, results indicated that psychological expert testimony which details
research findings concerning children's cognitive abilities seems less likely to
change verdicts than to increase the degree of certainty felt by those voting guilty,
and may therefore serve to improve the juridical decision-making process. The
impact of psychological expert testimony appears to vary with expert role when the
psychologist is male. Changingthe order in which testimony is presented appears to
have no significant impact on verdicts or jurors' perceptions of the child witness.
The implications of the thesis findings for psychological theory and legal practice are
discussed.
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Acknowledgements
Foremost and heartfelt thanks go to my supervisors, Gemma O'Caliaghan and
Peter Ball, for their advice and support and all aspects of their mentorship
throughout these years. Thanksalso to lain Montgomerywho exhorted me to set foot
on the doctoral path, and to all who assistedin myjourney along that road, including
Kate Warner and Therese Henning from the Faculty of Law for their advice and
assistance in preparing the trial transcripts, and Rick Snell, Emma Gunn, Trudy
Witbreuk, Gaby Piscioneri, Patrick Ryle, Cindy Calvert, Les Fisher and Irene
Fisher who portrayed the protagonists in the trial.
While assurances of confidentiality prevent my naming them, I would like to
express thanks to those parents who gave permission for their children to be
interviewed and videotaped, and especiallyto the children themselves, and to Marie
Louise Craske, the psychologist who interviewed them. My thanks also to the more
than 600 subjects who have assisted by acting as mock jurors in these experiments.
I am particularly indebted to them for the manifest seriousness with which they
approached their task.
A very special thanks to Brian Rieusset, Senior Technical Officer at the
University of Tasmania for his invaluable assistance in videotaping the children's
interviews and the mock trials, and for the many weeks of assistance he gave as we
sat editing videotapes.
I would like to thank Murray Levine and his colleagues at State University of New
York, Buffalo, for providing the deliberation content analysis codebook which they
used in their own studies and which I adapted for use with these trial scenarios.
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Finally, I would like to thank my wife, Elizabeth, and my children, Ursula, Luke,
Bede, Benedict and Lucy, who have supported me throughout the preparation,
videotaping, editing, subject recruitment, data collection, data analysis, and writing
up phases of this thesis, and havetolerated with good grace my frequent absenceor
unavailability.
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Table of Contents
Page
ABSTRACT iii
ACKNOWLEDGEMENTS v
TABLE OF CONTENTS vii
LIST OF TABLES xii
LIST OF FIGURES xv
LIST OF APPENDICES xvii
INTRODUCTION :
1 . Introduction 1
2. Evidentiaryanalysesof the scope and admissibilityof 5
psychological expert testimony with particular reference
tochildsexualabusecases:
A cross-national perspective
2.1 UnitedStatesofAmerica 6
2.2 UnitedKingdom 12
2.3 Europe 13
2.3.1 France
2.3.2 Germany
2.4 Australasia 15
3. Psychological experttestimonyin child sexual abuse cases 17
3.1 Psycho-legal treatment of the impact of psychological
expert testimony 18
3.2 Rationale for generalisedtestimony on children's
cognitive abilities 21
3.3 Empiricalstudiesof the impact of generalised
psychological expert testimony 24
3.4 Roleof the psychologistexpert in a child sexual
abusecase 25
3.5 Summary 29
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4. Jurors' reactions to child witnesses and expert witnesses 31
4.1 Empirical studies 32
4.2 Theoretical models 35
4.2.1 Hypotheses andmodelsformulated
specifically to explain aspects of jurors'
perceptionsof child witnesses. 35
4.2.2 Pertinent models and theories from social
psychology to elucidate the likely interplay
of childandexpertevidence. 37
4.2.3 Legal admonitions vs. legal reality: the juror
as fact-finder or fact-interpreter. 40
4.2.4 Predictionsfrom social psychology
concerning the relative impact of adversarial
and non-adversarial expert testimony 42
4.3 Summary 43
5. Summary of introductory material;
overview of thesis studies;
methodological issuesandrationales. 45
5.1 Summary of introductory material 46
5.2 Overview of experimental studies in thesis 47
5.3 Methodological issuesand rationales 49
5.3.1 The useof videotapedtrial presentations
rather than written transcripts or real life. 49
5.3.2 Rationale for the use of 6-person juries 51
5.3.3 Theneedforgenderbalancein research
involvingsexual assault cases 52
5.3.4 The useof an ambiguoustrial as stimulus 53
5.3.5 Stimulus sampling 53
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EXPERIMENTAL SECTION:
6. Experiment one: The juridical impact of psychological
expert testimony concerning children's cognitive abilities 55
6.1 Introduction 56
6.2 Method 57
6.2.1 Subjects 57
6.2.2 Experimental design 58
6.2.3 Material 58
6.2.4 Procedure 65
6.3 Results 66
6.4 Content analysisof deliberations 74
6.5 Discussion 80
6.6 Methodological considerations from Experiment 1 82
6.6.1 Brief duration of the simulation relative
to a real trial 83
6.6.2 Impartiality of the expert 83
6.6.3 Ecological validity of using undergraduate
vs. community subjects 84
6.7 Summary and legal implications 86
7. Experimenttwo : The impact of adversarialversus
non-adversarial expert testimony in a simulated
childsexualabuse case 88
7.1 Introduction 89
7.2 Method 90
7.2.1 Subjects 90
7.2.2 Experimental design 91
7.2.3 Material 91
7.2.4 Procedure 92
7.3 Results 92
7.4 Content analysis of deliberations 104
7.5 Discussion 106
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