FIRST IMPRESSIONS FROM THE JURY BOX

110 Pages·2010·0.38 MB·English

FIRST IMPRESSIONS FROM THE JURY BOX: HOW THE LENGTH OF
EXPERT WITNESS TESTIMONY INFLUENCES
MOCK TRIAL DELIBERATIONS

by
CAROLINE RICHARDS TITCOMB

A THESIS

Submitted in partial fulfillment of the requirements
for the degree of Master of Arts
in the Department of Psychology
in the Graduate School of
The University of Alabama

TUSCALOOSA, ALABAMA

2010
Copyright Caroline Richards Titcomb 2010
ALL RIGHTS RESERVED
ABSTRACT
The present study examined the influence that a juror's first impressions of an expert
witness might have on two outcomes: judgments of the witness’ credibility, and verdict decisions
in a criminal case involving a Not Guilty by Insanity (NGRI) defense. This was the first study to
use “thin slice” methodology to manipulate time exposed to expert testimony and assess
reliability of witness credibility ratings over time. This study also examined the degree to which
these impressions influence the relationship between juror opinions and jury decision-making. A
2 (non-deliberating vs. deliberating jury) X 3 (observing 30 seconds, 5 minutes, or 10 minutes of
expert witness testimony) between subjects design was implemented. Participants (N = 188, 30
mock juries) viewed a videotaped presentation of testimony from an actor portraying a forensic
mental health professional called on by the defense. Mock juror characteristics, responses to a
thought listing measure, and transcriptions from the videotaped jury deliberations were coded for
exploratory analysis. Primary results, obtained via Hierarchical Linear Mixed Modeling to
account for the random effect of group, were supported by jury-level analysis. Despite support
for the accuracy of “thin slice” judgments in the literature, results found that jurors in the 30
second condition judged the expert as significantly less credible in this study. Results did not
support the anticipated leniency shift in juries post-deliberation, and instead, yielded a significant
two-way interaction on verdict for the 30 second group, such that non-deliberating jurors were
more lenient than deliberating jurors. Implications for understanding how impressions of expert
witness testimony translate from the juror to the deliberation room are discussed, with particular
attention to cases with an increased likelihood of bias against the NGRI defense.
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DEDICATION

This thesis is dedicated to my mentor, Stanley L. Brodsky, PhD., whose passion for
research, and talent for turning all of life’s moments into teachable ones, has guided me through
this process. Thanks to Stan’s mentoring, I emerged from this intensive project even more
enthusiastic about forensic psychology research, and equipped with the knowledge and
confidence necessary to continue and succeed in the field.

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LIST OF ABBREVIATIONS AND SYMBOLS
α Chronbach’s alpha coefficient (degree of internal consistency)
ANCOVA Analysis of Covariance
b or B Computed value of the unstandardized regression coefficient (parameter estimate)
b/se Effect size (coefficient/ computed standardized error for each parameter estimate)
Cramer’s V Effect size for Pearson’s chi-square tests of independence (for contingency tables
greater than 2 x 2)
d Cohen’s d (measure of effect size, strength of relationship)
F Fisher’s F Ratio
GLM General Linear Modeling
HLM Hierarchical Linear Modeling
K Cohen’s Kappa coefficient (measure of inter-rater reliability)
LMM Linear Mixed Modeling
LSD Least significant difference
M Mean (arithmetic average)
N Number of participants
η 2 Partial eta squared (strength of observed power)
p
NGRI Not Guilty by Reason of Insanity defense
p Probability
p. Page number
r Pearson’s correlation (measure of association between variables)
iv
SD Standard deviation
x2 Pearson’s chi-square statistic
z Standardized residual
< Less than
= Equal to
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ACKNOWLEDGEMENTS
The enclosed thesis would not have been possible without the guidance and support of
my family, friends, colleagues, and mentors. I would like to extend a heartfelt thank you to
Stanley, my academic mentor and thesis committee chairperson, for his invaluable wisdom and
encouragement. I would also like to thank Steve Prentice-Dunn for his instrumental role in
developing the study, and Clay Shealy for his feedback and enthusiasm about this endeavor.
I am grateful to John Toppins, Stanley Brodsky, Jennifer Kelly, and Tess Neal for their
part during the filming of the stimulus. Thank you to Jamie DeCoster and Rosanna Guadagno for
ushering me through the project’s statistical challenges. I would also like to thank my colleagues,
Tess Neal, Mitch Ziemke, and Robert Cramer for their feedback in all aspects of this project;
methodological, statistical, and practical. Thank you to Jennifer Kelly, Kerry Johnson, Rachel
Davis, Jacklyn Nagle, Maddy Semon, and Sarah Patterson for making themselves readily
available to assist with running research participants, entering data, and coding the qualitative
aspects of this research. Furthermore, thank you Scott Parrott, Debra Chen, Patrick O’Brien,
Krystal Hedge, and Whitney Lester for their friendship and suggestions throughout this process.
I would also like to take this opportunity to thank my mother and step-father, Pegeen and
Michael Sites, for their guidance and encouragement; and my father, Richards Titcomb, for
motivating my academic endeavors and for providing counsel throughout my life. A heartfelt
thank you to Scott Parrott, Nicole Russell, Sarah Draper, Edwin Penn, and Walker Shank and his
family for always reminding me of the important things in life. Finally, thank you to all my
friends and family for their humor and loving support throughout this process.
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CONTENTS
ABSTRACT………………………………………………………………………………ii
DEDICATION…………………………………………………………………………...iii
LIST OF ABBREVIATIONS AND SYMBOLS………………………………………...iv
ACKNOWLEDGEMENTS……………………………………………………………....vi
LIST OF TABLES…………………………………………………………………...…viii
LIST OF FIGURES…………………………………………………………………........ix
1. INTRODUCTION……………………………………………………………………..1
2. METHOD…………………………………………………………………………….15
3. RESULTS…………………………………………………………………………….29
4. DISCUSSION……………………………………..………………………………….54
REFERENCES…………………………………………………………………………..68
APPENDICES……………………………………………………………………….......80

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LIST OF TABLES
1. Means (and Standard Deviations) for Mock Juror Ratings by Experimental Condition
on the four WCS facets………………………………………………………………..…37
2. Means (and Standard Deviations) for Juror Verdict Ratings by Experimental
Condition………………………………………………………………………………...38
3. Means (and Standard Deviations) for “Defendant Guilt” Ratings by Condition…......39
4. Verdict Percentages (and N) by Experimental Condition…………………………….41
5. Means (and Standard Deviations) for Jury Outcomes by Experimental Condition…..42

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LIST OF FIGURES
1. Hypothesized two-way interaction of deliberation and time slice on verdict…………13
2. Significant two-way interaction between time slice and deliberation on verdict……..33
3. Main effects of time slice on witness credibility facets……………………...……..…36
4. Message agreement cognitions from the TLM………………..……………….……...48
5. Sentencing thoughts from the TLM…………………………………………….……..48
6. Culpability cognitions from the TLM………………………………………….……...49
7. Stimulus driven thoughts from the TLM………………………………………..…….49
8. Significant two-way interaction between time slice and deliberation on degree of
influence testimony had on verdict……………………………………………….……...51
9. Marginally significant trend for a two-way interaction between deliberation and time
slice on reported influence of mock juror bias against defendant………………….……53

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