1. An Experimental Study Examining the Effects of Confessional and Circumstantial
Evidence on Potential Jurors
Thomas Cox, University of Tennessee, Knoxville
865-441-5720, tcox25@vols.utk.edu
Brittany Hawk, University of Tennessee, Knoxville
865-974-2535, bhawk1@vols.utk.edu
Julia Van Hooser, University of Tennessee, Knoxville
615-969-8589, jvanhoo1@vols.utk.edu
Jackie Garner, University of Tennessee, Knoxville
423-767-8040, jgarne26@vols.utk.edu
Luis Ruuska, University of Tennessee, Knoxville
815-566-0117, lruuska@vols.utk.edu

2. Abstract
The purpose of this research report documenting the results of an experiment
carried out by the researchers is to provide evidence to support the hypothesis that jurors
are impacted to a greater degree by confessional evidence than by circumstantial
evidence. After
reviewing
the
related
literature,
30
participants
were
asked
to
rate
how
guilty
they
find
the
defendant
after
being
presented
with
two
separate
scenarios
that
provide
either
circumstantial
or
confessional
evidence.
The results of
this experiment were found to have a positive correlation with the primary hypothesis.
Not only are people more likely to find a defendant guilty when presented with
confessional evidence, but people are more certain of their predictions in these cases as
well.
Keywords: Circumstantial evidence, coerced confessions, criminal trials, criminal law,
direct evidence, juries, law, wrongful imprisonment

3. An Experimental Study Examining the Effects of Confessional and Circumstantial
Evidence on Potential Jurors
There is an extensive body of interdisciplinary research that supports the
hypothesis that, “confessions have a greater impact on juries than other types of evidence,
sometimes in the face of contradictory evidence” (Appleby, Hasel, & Kassin, 2013, p.
111). This knowledge, known amongst criminal attorneys, prosecutors, and law
enforcement, has, in numerous documented situations, created morally ambiguous
situations in which coerced confessions are extracted from subjects to their own
detriment. However, in order to fully understand the extensive body of research on the
relationship between confessions and the impact on juries that has been published in
recent decades, it is imperative to understand a few key concepts and conceptual
definitions.
Circumstantial and Direct Evidence
Within the American legal system, there are two main types of evidence that are
admissible in a court of law in both civil and criminal trials: direct evidence (which may
include eyewitness testimony) and indirect evidence (also known as circumstantial
evidence). As defined by Kim, Barak, & Shelton (2009), “Circumstantial, or indirect,
evidence is evidence that normally or reasonably leads to other facts and requires judges'
or jury's interpretation and inference about the causation” (p. 454). A classic case of
circumstantial evidence is the person whose cellphone records show that they were in the
general area in which a crime occurred within the timeframe that the crime occurred at.
Although there are numerous valid reasons as to why that person may have been in the

4. area at the time that they were, the presentation of this evidence by an attorney is meant
to create a convincing link between the person and the crime in the minds of jurors or a
judge, even if no such link exists in reality beyond coincidence. In contrast, direct
evidence is “evidence that is based on personal knowledge or observation and that, if
true, proves a fact without inference or presumption” (Barton, 2003, p.45) Direct
evidence may be presented in a court of law in numerous ways. It can include recorded
material such as photographs, videos, or audio recordings. Direct evidence may also
include eyewitness testimony, although various researchers have demonstrated that
eyewitness testimony may be unreliable, with “witnesses often [making] a relative
judgment, identifying the suspect who looks the most like the perpetrator, even when the
perpetrator is absent” (Weinberg, 2012, p. 49). Finally, direct evidence may include a
confession, which is a direct admission of guilt on the part of the defendant.
Coerced Confessions
In the landmark study conducted by Bedau & Randelet (1987), researchers
identified 350 instances in which innocent persons were wrongfully convicted of capital
crimes, 49 of which were due to coerced confessions (p. 57). Ofshe (1989) built off of
this research to examine the psychology behind coerced confessions and why subjects
confess, even when it is irrational to do so. Ofshe discovered that there are several
interrogation tactics used to persuade subjects to confess, including “Convincing the
suspect that his situation is hopeless because the evidence against him is sufficient to
produce a successful prosecution … Manipulating the suspect's emotional state by
attempting to make the stress of continuing to deny responsibility greater than the
suspect's anxiety about admitting guilt … [And] manipulating the suspect's expectations

5. about the level of punishment that will follow from immediately confessing as opposed to
continuing to hold to a denial of guilt” (Ofshe, 1989, p. 1-15). Ofshe suggests that such
practices are unethical, but also states that such tactics are accepted within interrogation
settings (1989, p. 1-15).
Juror Consideration of Confessions
Numerous scholars and researchers from the fields of law, sociology, and
psychology have agreed that coerced confessions threaten not only those who are
coerced, but the institution of justice itself. This is primarily because an extensive body of
research has been produced by researching the effects confessions, coerced or not, have
on juries and the verdicts they make as a result. Research has shown that jurors have a
strong preference for confessional evidence and that is “seen as the most incriminating,
followed by eyewitness and character testimony” (Kassin & Neumann, 1997, p. 469). So
strong is the preference for confessional evidence that jurors, even when told that a
confession may have been coerced, will rarely ever discount it as valid evidence (Kassin,
2015, p. 38).
With this prior research in mind, the following experimental study was carried out
in order to support previous hypotheses that jurors are impacted to a greater degree by
confessional evidence than circumstantial evidence.
Methods
Participants
The participants of this study included 30 undergraduate students on campus at
the University of Tennessee. The subjects of this experiment participated on a volunteer
basis as 2 groups of 15 subjects. The subjects participated on November 18, 2015 in

6. Hodges Library. The first group of 15 were asked at 12:30 p.m. and the second group of
15 were asked at 2:30 p.m.
Materials and Procedure
The experiment was conducted by posing two different scenarios to the
participants: an example with circumstantial evidence and an example with confessional
evidence. The scenario posed to both groups stated,“Jones has harbored ill feelings
toward Smith for some time because of gambling losses. Both Jones and Smith work on
the fourth floor of an office building. One evening Smith is shot and killed in his office.
Jones is accused of the crime, and you are a juror at his trial.” The circumstantial
evidence then concluded with the statement, “Jones was working in the office the night
that Smith was killed.” The confession condition concluded with the statement, “Jones
confessed to the police that he had committed the crime.” Both groups were then asked
to rate how guilty or innocent they viewed Jones. They then had to rate on a scale from 1-
5 their likelihood of finding Jones innocent. 1 meant they believed he was innocent, 2
meant he was probably innocent, 3 meant they were unsure, 4 meant he was probably
guilty, and 5 meant they would find him guilty.They were then asked to rate on a scale
from 1-5 how certain of their judgement they were. 1 meant they were not certain, 2
meant they were mostly not certain, 3 meant neutral, 4 was mostly certain, and 5 was
certain.
Instrumentation
Fifteen participants were read the scenario that corresponded with circumstantial
evidence while fifteen other participants were read the scenario that corresponded with

7. the confession condition. The data was recorded with smart phones and with pen and
paper.
Results
The results of this experiment conclude that the group of 15 participants who
were presented with confessional evidence (group 2) were more likely to find the
defendant guilty than were the 15 people presented with circumstantial evidence (group
1). Not only was group 2 more likely to find the defendant guilty but they were also more
certain of their verdict in these cases as well. Using SPSS software the raw data from
both groups were tested and reported in the form of a T-Test group statistic table, an
independent samples table, a bar graph, and a frequency rating table. After viewing the
means, standard deviations, frequencies, and the correlations both groups were compared.
Likelihood Results
Table 1 shows that the mean of likelihood ratings of group 1 (3.6) is significantly
lower than the mean of group 2 (4.4). This is because people reported that the likelihood
that they would find the defendant guilty when presented with confessional evidence is
much higher than when presented with circumstantial evidence. Table 2 shows that there
is significant difference when the variances are assumed vs. not assumed after conducting
the 2-tailed t-test (.013, .014). Figure 1 shows that the likelihood that people would find
the defendant guilty was much higher for the members of group 2 (confessional). Only 1
person out of 15 reported a likelihood of 5 when presented with circumstantial evidence,
while 10 from group 2 reported a definitive likelihood of 5. Table 3 shows the frequency
of likelihood ratings reported. The frequency of 5s reported were much higher in group 2
with a 6.7 to 66.7 percent ratio.

8. Certainty Results
Table 4 shows that people were more certain of their verdict when presented with
the confessional evidence. The mean of results in group 1 (circumstantial) is 3.4667 and
the mean of results in group 2 (confessional) is 4.333. Also the standard deviation of
group 1 was considerably higher than in group 2. This data strongly supports the
assumption that certainty is stronger when presented with confessional evidence. Table 5
shows that there is significant difference when the variances are assumed vs. not assumed
after conducting the 2-tailed t-test. (037, .039). Figure 2 compares the reported ratings of
group 1 in blue and group 2 in green. Notice that no one in group 2 reported the lowest
rating of certainty possible (1.00). Table 6 shows the frequency of certainty ratings
reported. The frequency of 4s and 5s reported were much higher in group 2 than in group
1.
Discussion
The data collected and presented in this research report largely supports the hypothesis
that jurors are impacted to a greater degree by confessional evidence than by
circumstantial evidence. The mock jury of 15 that were read the circumstantial evidence
situation by and large were more likely to find the hypothetical Mr. Jones guilty than the
mock jury of 15 that were read the confessional evidence situation, as shown in the prior
section.
Limitations of the Present Study
The researchers acknowledge several limitations to the present study. The first
limitation present in this experiment was age of the participants. All 30 participants were
between the ages of 18-21. Because jurors come from a wide range of age groups, this

9. study cannot definitively make any conclusions about jurors at-large due to the small
sample size. Furthermore, it is possible that the age of participants has an effect on
judgment with younger potential jurors rushing to judgement more quickly than older
potential jurors. Second, all participants were of the same average education level as well
as socioeconomic background. These factors could affect how each participant
approaches the situation. Another limitation in this experiment deals with the scenario
being read to them as opposed to the individual reading it for himself or herself. If the
participants had read the scenario for themselves, different words could have been
emphasized to them and caused their response to differ in comparison to having only
heard the facts read aloud.
Conclusions and Future Prospects
Despite the limitations of this research report, the researchers believe that it is
useful by contributing to the larger interdisciplinary body of psychological, sociological,
and legal research on the subject of coerced confessions. There is still a great deal of
potential research to be done in all of the aforementioned fields. Future psychological
researchers, for instance, might find it beneficial to examine whether jurors have more
confidence in finding a subject guilty when they view a taped confession or are presented
with visual circumstantial evidence (such as cell phone tower location records), as
opposed to having each respective situation read to them, as was done in this experiment.
Future researchers also might find it beneficial to conduct longitudinal studies regarding
whether jurors maintain their preference for confession-based evidence over time and at
different ages. Similarly, future researchers could conduct experiments to see whether
there are differences by age-group in the preference for confession-based evidence. There

10. is also great potential for studying this subject matter through a sociological lens and
examining whether different cultures view confessions differently. For instance, within
the Roman Catholic religious tradition the Sacrament of Penance and Reconciliation (also
known as penance) is one of the core tenets of Catholic culture. However, not all
religious traditions, even within the broader Christian movement, have a similar emphasis
on the confession of one’s sins. Future researchers might look into whether one’s
religious upbringing or current practice has an effect on how they view confession-based
evidence versus circumstantial evidence in the courtroom. The results of such research
could have broader implications for the legal field and lead to attorneys considering such
research during voir dire (the process of jury selection).

11. References
Appleby, S. C., Hasel, L. E., & Kassin, S. M. (2013). Police-induced confessions: an
empirical analysis of their content and impact. Psychology, Crime & Law, 19(2), 111.
Barton, R. J. (2003). Determining the Meaning of “Direct Evidence” in Discrimination Cases
Within the 11th Circuit Why Judge Tjoflat Was (W)right. The Florida Bar Journal, (9),
45.
Bedau, H. A., & Radelet, M. L. (1987). Miscarriages of Justice in Potentially Capital Cases.
Stanford Law Review, 40(1), 57.
Kassin, S. M. (2015). The Social Psychology of False Confessions. Social Issues and Policy
Review, 9(1), 38.
Kassin, S. M., & Neumann, K. (1997). On the Power of Confession Evidence: An
Experimental Test of the Fundamental Difference Hypothesis. Law and Human Behavior,
21(5), 469.
Kim, Y. S., Barak, G., & Shelton, D. E. (2009). Examining the “CSI-effect” in the cases of
circumstantial evidence and eyewitness testimony: Multivariate and path analyses.
Journal of Criminal Justice, (37), 452–460.
Ofshe, R. (1989). Coerced Confessions: The Logic of Seemingly Irrational Action. Cultic
Studies Journal, (6), 1–3.
Weinberg, S. (2012). Seeing is believing: in experiment after experiment, Gary Wells has
established that eyewitness testimony is unreliable and leads to wrongful convictions.

12. Why has the judicial system not adopted his recommendations? The American Prospect,
49.

13. Tables and Figures
Likelihood Results
Figure 1: Compares the likelihood ratings of group 1 (blue, circumstancial), and group 2
(green, confessional).
Group Statistics
Group N Mean Std. Deviation Std. Error Mean
Likelihood 1.00 15 3.6000 .63246 .16330

14. 2.00 15 4.4000 .98561 .25448
Table 1: Compares the mean, median and standard deviation of each groups.
Independent Samples Test
Levene's
Test for
Equality of
Variances
t-test for Equality of Means
F Sig
.
t df Sig.
(2-
taile
d)
Mean
Differenc
e
Std.
Error
Differenc
e
95% Confidence
Interval of the
Difference
Lower Uppe
r
Likelihoo
d
Equal
varianc
es
assume
d
2.47
1
.12
7
-
2.64
6
28 .013 -.80000 .30237 -
1.4193
8
-
.1806
2
Equal
varianc
es not
assume
d
-
2.64
6
23.85
8
.014 -.80000 .30237 -
1.4242
6
-
.1757
4
Table 2: 2 tailed T-Test shows the significance of the differentials when there are
variances assumed vs. not assumed.

15. Table 3: This table compares the frequencies reported by each group. For example the
group presented with circumstancial evidence had the highest amount of 5’s reported for
likelihood with 66.7 percent.
Certainty Results

16. Figure 2: Bar graph compares the certainty rating reported by group 1 (blue,
circumstancial), and group 2 (green, confessional).
Table 4: Compares the mean, median and standard deviation of each group.

17. Independent Samples Test
Levene's
Test for
Equality of
Variances
t-test for Equality of Means
F Sig
.
t df Sig.
(2-
taile
d)
Mean
Differen
ce
Std.
Error
Differen
ce
95% Confidence
Interval of the
Difference
Lower Uppe
r
Certain
ty
Equal
varianc
es
assume
d
2.25
6
.14
4
-
2.18
4
28 .037 -.86667 .39681 -
1.6795
0
-
.0538
3
Equal
varianc
es not
assume
d
-
2.18
4
23.53
6
.039 -.86667 .39681 -
1.6865
0
-
.0468
3
Table 5: 2 tailed T-Test shows the significance of the differentials when there are
variances assumed vs. not assumed.
Certainty
Group
Frequency Percent Valid
Percent
Cumulative
Percent
1.00 Valid 1.00 2 13.3 13.3 13.3
3.00 6 40.0 40.0 53.3
4.00 3 20.0 20.0 73.3
5.00 4 26.7 26.7 100.0
Total 15 100.0 100.0
2.00 Valid 3.00 3 20.0 20.0 20.0
4.00 4 26.7 26.7 46.7
5.00 8 53.3 53.3 100.0
Total 15 100.0 100.0
Table 6: This table compares the frequencies of certainty ratings reported by each group.