Potential labeling effects: Influence of psychopathy diagnosis, defendant age, and defendant gender on mock jurors’ decisions

Potential labeling effects: Influence of psychopathy diagnosis, defendant age, and defendant gender on mock jurors’ decisions

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/240031741

Article in Psychology Crime and Law · January 2013

DOI: 10.1080/1068316X.2012.749473

2 authors, including:

Julie Blais & Adelle E. Forth Carleton University

Some of the authors of this publication are also working on these related projects:

Julie Blais Carleton University

Psychopathy and victim selection View project


Author Note

Julie Blais, Department of Psychology, Carleton University; Adelle E. Forth, Department of Psychology, Carleton University. Correspondence concerning this article should be addressed to Julie Blais, Department of Psychology, Carleton University, Ottawa, ON, K1S 5B6. Phone: (613) 520-2600, ext 1408. E-Mail: jblais2@connect.carleton.ca



The present study investigated the impact of diagnostic labels and traits, age, and gender of the defendant on various mock juror decisions. Undergraduate students and members of the community (N = 247) read a simulated trial transcript involving a case of aggravated assault. The transcript differed in terms of diagnosis (psychopathy vs. antisocial personality disorder/conduct disorder vs. no diagnosis), age (15 vs. 30), and gender (male vs. female) of the defendant. The effects of these variables on decisions regarding credibility, verdict choice, risk of future violence and recidivism, and treatment amenability were investigated. Results indicated that psychopathic defendants were rated as being less credible than defendants in the other diagnostic conditions. Defendants described as psychopaths and as having antisocial personality disorder/conduct disorder were also more likely to be found guilty and were more likely to receive higher ratings of risk for future violence/recidivism regardless of their age and gender. There were no significant main effects or interactions concerning the age and gender variables. Implications for the use of psychopathy evidence within the Criminal Justice System are discussed.


Potential labeling effects: Influence of psychopathy diagnosis, defendant age, and defendant gender on mock jurors’ decisions

In recent years, psychopathy assessments have increasingly been used within the Criminal Justice System (CJS) to inform decisions concerning an offender’s potential risk for future recidivism as well as their potential for treatment amenability (DeMatteo & Edens, 2006; Viljoen, McLachlan, & Vincent, 2010; Walsh & Walsh, 2006; Zinger & Forth, 1998). Given this increased use, it becomes imperative to discover whether these decisions are reflective of the available literature on psychopathy and whether they are unjustly punitive (Petrila & Skeem, 2003). Research has also demonstrated differences in the application of psychopathy across age (e.g., positive treatment outcomes and developmental considerations; Caldwell, McCormick, Umstead, & Van Rybroek, 2007; Salekin, Rogers, & Machin, 2001) and gender (differences in predictive validity; Dolan & Völlm, 2009; Verona, Sadeh, & Javdani, 2010), which may potentially impact the validity of extending the psychopathy diagnosis to youth and female offenders.

Several studies have examined the potential biasing effects of psychopathy as compared to other mental disorders such as psychotic disorder or conduct disorder (CD) (Boccaccini, Murrie, Clark, & Cornell, 2008; Edens, Colwell, Desforges, & Fernandez, 2005; Edens, Desforges, Fernandez, & Palac, 2004; Murrie, Boccaccini, McCoy, & Cornell, 2007; Murrie, Cornell, & McCoy, 2005; Rockett, Murrie, & Boccaccini, 2007). Other studies have examined the potential biasing effects of diagnostic labels and criterion (or trait) descriptions versus no disorders and positive traits such as honesty, showing remorse for actions, and taking responsibility for actions (Edens, Guy, & Fernandez, 2003; Murrie et al., 2005, 2007; Vidal & Skeem, 2007; Rockett et al., 2007) or the biasing effects of the diagnostic label versus the diagnostic criterion description itself (Chauhan, Reppucci, & Burnette, 2007; Jones & Cauffman, 2008). Researchers have varied the language used to describe whether the defendant is labeled a psychopath with some studies using “meets criteria for psychopathy” or “has a psychopathic personality disorder” (Edens et al., 2004, 2005; Murrie et al., 2005, 2007) and others stating the defendant “is a psychopath” (Boccaccini et al., 2008; Chauhan et al., 2007; Cox, DeMatteo, & Foster, 2010; Jones & Cauffman, 2008; Vidal & Skeem, 2007). Finally, researchers have also included a range of other manipulations such as risk level (Cox et al., 2010; Edens et al., 2004), history of antisocial behaviors (Boccaccini et al., 2008; Murrie et al., 2005, 2007; Rockett et al., 2007), ethnicity of defendant (Edens et al., 2003; Vidal & Skeem, 2007), history of childhood abuse (Edens et al., 2003; Vidal & Skeem, 2007), or diagnosis of severe mental retardation (Edens et al., 2004). The outcome measures used in these studies have varied but most have focused on recommended sanctions or sentences, ratings of risk or dangerousness, and how amenable the defendant is to treatment or treatment recommendations. Table 1 summarizes the results of the eleven published studies measuring the effects of the psychopathic label and/or traits. In terms of adult defendants, two studies using mock jurors have concluded that using the psychopathy label and trait descriptions results in increased ratings of future dangerousness. These studies have also shown that the negative results are seen for diagnostic labels and traits in general (e.g., psychotic disorder) and not solely for psychopathy (Edens et al., 2004, 2005). A further study also utilizing mock jurors demonstrated that isolating the effect of the “psychopath” label itself produced no significant results concerning increased risk and increased support of capital punishment (Cox et al., 2010).

In terms of youth, researchers have demonstrated that describing a youth defendant using both the psychopathy label and underlying traits results in more punitive decision making among juvenile probation officers, potential jurors, juvenile justice judges, and clinicians (Boccaccini et al., 2008; Murrie et al., 2005, 2007; Rockett et al., 2007). More specifically, these studies have demonstrated that ascribing psychopathic traits to the individual results in harsher sentence recommendations and higher ratings of risk. Results for treatment amenability, however, are less consistent. Some studies have found no negative treatment beliefs associated with psychopathic traits (Boccaccini et al., 2008; Murrie et al., 2005; Rockett et al., 2007), whereas others have found the psychopathy label and traits to be associated with more punitive beliefs about treatment as compared to no disorder or positive traits (Chauhan et al., 2007; Edens et al., 2005; Jones & Cauffman, 2008). Further studies have also reported that defendants described as psychopathic were rated as being in need of more treatment (Boccaccini et al., 2008; Murrie et al., 2005, 2007). From these studies, several major conclusions can be drawn: 1) using psychopathic traits produces stronger effects compared to using the label alone; 2) negative effects of psychopathy traits have been found most consistently for decisions regarding dangerousness and harsher sanctions; and 3) there is strong evidence for a general labeling effect not specific to psychopathy. To date, all of the published research has used cases of male defendants and none have examined the age of the defendant in the same study. In addition, none of the published literature has assessed the biasing influence of the most prevalent personality disorder in offenders: antisocial personality disorder (APD).

[Insert Table 1]




In order to assess the validity of the decisions rendered by members of the CJS and more specifically, by mock jurors (the sample of the current study), it is necessary to examine the scientific literature on psychopathy. One of the main interpersonal features of psychopathy is the propensity to engage in the deception and manipulation of others (Hare, 2003). Research exploring psychopaths’ actual deception ability has been mixed with some studies showing psychopath’s proficiency in deception (Edens, Buffington, Tomicic, & Riley, 2001), while others showing no difference between psychopaths and non- psychopaths (MacNeil & Holden, 2006). Despite academic debate, media portrayals of psychopaths emphasize their callous-unemotional traits as well as their ability to manipulate and deceive others (Stevens, 2008) making these traits more salient to laypersons.

Several meta-analyses have confirmed the relationship between antisocial conduct, violence, and psychopathy in adult male offenders (Hemphill, Hare, & Wong, 1998; Leistico, Salekin, DeCoster, & Rogers, 2008; Walters, 2003a, 2003b). Similar results have also been reported in samples of youth offenders with psychopathic traits (Edens & Campbell, 2007; Edens, Campbell, & Weir, 2006). It has also been consistently reported that Factor 2 (items measuring behavioral and antisocial features) of the Psychopathy Checklist-Revised (PCL-R; Hare, 2001, 2003) is more predictive of general and violent recidivism in adult offenders compared to Factor 1 (items measuring interpersonal and affective features) (Hemphill et al., 1998; Leistico et al., 2008; Walters, 2003a, 2003b).

Based on these studies, it is reasonable to suggest that an assessment of psychopathy should be included when making judgments concerning an offender’s future risk for recidivism in male offenders. In addition, mock jurors may also take into consideration whether psychopathic offenders can benefit from treatment when making their decisions. In samples of adult offenders, there have been several reviews of the treatment literature with some being pessimistic about the treatment amenability of psychopaths (e.g., Harris & Rice, 2006) and others being more optimistic (D’Silva, Duggan, & McCarthy, 2004; Salekin, 2002). Generally, it is argued that there is insufficient empirical evidence to conclude that psychopaths are untreatable (for a review see Doren & Yates, 2008; D’Silva et al., 2004).

In populations of youth offenders, although it has been demonstrated that they are more difficult to treat (O’Neill, Lidz, & Heilbrun, 2003; Rogers, Vitacco, Cruise, Sewell, & Neumann, 2002; Spain, Douglas, Poythress, & Epstein, 2004), studies examining post treatment outcomes have found that intensive treatment programs can lead to positive outcomes even among youth with many psychopathic traits (Caldwell et al., 2007; Caldwell, Skeem, Salekin, & Van Rybroek, 2006). Given the empirical literature on psychopathy and treatment, the question remains whether potential jurors are more optimistic concerning treatment outcomes of youth psychopathic offenders compared to adult psychopathic offenders. More general research on the effect of defendant age on decisions rendered by mock jurors has shown that younger defendants are given more lenient sentences compared to older defendants (Bergeron & McKelvie, 2004; Smith & Hed, 1979), however, this finding has not always been replicated (Loeffler & Lawson, 2002). It is important to note that the defendants described in these studies have all been adults (no manipulation of adolescent vs. adult defendant).

Another important factor that can be considered in labeling studies is the effect of defendant gender. In terms of the rates of female psychopathy, the majority of studies have found lower PCL-R scores for females in samples of substance abusers (Alterman, Cacciola, & Rutherford, 1993), forensic psychiatric patients (Grann, 2000), and offenders (Vitale, Smith, Brinkley, & Newman, 2002). In terms of the predictive validity of psychopathy in samples of female adult offenders, results have been conflicting; some studies have shown that total psychopathy scores are not predictive of recidivism (Salekin, Rogers, Ustad, & Sewell, 1998) while others have shown that some features of psychopathy (e.g., affective-interpersonal characteristics) are predictive of recidivism (see Dolan & Völlm, 2009 for review). It appears that there are both similarities and differences in the presentation and predictive validity of psychopathy across men and women. More general studies on the effect of defendant gender on decisions rendered by mock jurors have focused on the study of sexually motivated crimes and have found female defendants to be treated more leniently than male defendants (Heatherton & Beardsall, 1998; Pozzulo, Demspey, Maeder, & Allen, 2010; Rogers & Davies, 1997). It is unclear from the literature whether defendant gender is considered by mock jurors for non-sexual violent crimes.

While the relationship between psychopathy and APD has been widely debated in the broader psychopathy literature (for a review see Lilienfeld, 1998), it has not been examined in the context of labeling research. Evidence has demonstrated that in correctional settings, 70-80% of offenders would meet the criteria for APD whereas only one third of these offenders would also meet the criteria for psychopathy (Widiger & Corbitt, 1995). Although some researchers claim that the two diagnoses are essentially the same (American Psychiatric Association, 1994; Widiger, 2006), others are adamant that while “the listed criteria for [APD] actually identify individuals who are persistently antisocial, most…are not psychopaths” (Hare, 1998, p. 191). Given the prevalence of APD compared to the prevalence of psychopathy, it would be worthwhile to know if mock jurors are able to distinguish between the disorders.


Current Study

The present study investigated the impact of diagnostic labels and traits, age, and gender of the defendant on mock jurors’ decisions about credibility, verdict choice, risk for recidivism and violence, and treatment amenability using a 3 (diagnostic label/traits: psychopathy vs. APD or CD vs. no diagnosis) x 2 (gender: male vs. female) x 2 (age: 30 vs. 15 years old) between-subjects design. The first variable, diagnostic label/traits, consisted of three separate levels: psychopathy, APD or CD, and no diagnosis. A description of APD was used when the offender was described as an adult, and CD was used when the offender was described as a youth thereby eliminating inappropriate diagnostic conditions (e.g., youth diagnosed with APD). Trait descriptions of each diagnosis were used as well as the labels themselves based on findings that using labels alone does not typically provide significant results (Murrie et al., 2005, 2007). The diagnostic information was manipulated by changing the testimony of a court-appointed psychologist using similar language from past labeling research (i.e., “is a psychopath”). The variables age (30 years old and 15 years old) and gender (female and male) were manipulated by changing the description of the defendant presented at the beginning of the trial transcript and the pronouns used throughout the testimony of the defendant and victim (the defendant and victim were matched on gender and age). The different age categories were chosen to clearly reflect a difference between adolescence and adulthood.

Given the widely publicized association between psychopathy and deception/manipulation (Stevens, 2008), we first hypothesized that mock jurors would find defendants described as psychopathic as being less credible than defendants described as APD/CD or as having no disorder. Given this same association, we also hypothesized that psychopathic defendants would be given higher ratings of guilt. Consistent with the psychopathy and labeling literature, we hypothesized that mock jurors would assign higher ratings of future risk for violence and recidivism and lower ratings of treatment amenability to offenders described as psychopathic and offenders described as having APD/CD compared to offenders with no diagnosis. Based on the general mock juror literature concerning age and gender, we chose to view these variables as potential mitigating factors. We therefore hypothesized that mock jurors would be more lenient towards female defendants and towards youth defendants as compared to male and adult defendants regardless of diagnosis.





Two hundred and ninety-five participants were recruited from a first year psychology undergraduate pool and from the community through an email campaign. Both student and community members were recruited in order to ensure a large enough sample size for the study (due to collection method, analyses between these two groups was not possible). In order to closely resemble eligible jurors, participants were required to be a citizen of Canada and at least 18 years of age. A total of 48 participants were eliminated because they either failed to correctly respond to the manipulation check questions (n = 42) and/or failed to respond to one or more of the questionnaires (n = 6). Therefore, the total number of participants included in the analysis was 247 (95 men and 145 women, 7 declined to respond). The average age of the participants in the final sample was 23.74 (SD = 9.06, Range: 18 – 61 years). The majority identified themselves as Caucasian (n = 194, 79%) with most of the participants being students (n = 196, 80%) and nearly everyone having achieved a high-school diploma (n = 243, 99%). The number of participants in each of the 12 possible conditions ranged from 19 to 23.



 Participants were asked to read a simulated trial transcript (approximately 4 pages in length) which described a case of aggravated assault where the defendant was claiming self-defense. The transcript consisted of opening statements by the Prosecution and Defense followed by the questioning and cross-examination of both the defendant and victim (full transcript and further information on the scenario used are available upon request). No other evidence was presented beyond the testimony of both parties involved leaving the case with a certain amount of ambiguity concerning the culpability of the defendant. The transcript also described a brief psychological assessment of the defendant conducted by a court appointed clinical psychologist (Appendix A). Finally, the judge’s instructions to the jury included a description of aggravated assault, the definition of self-defense, and a caution to view all information without bias.

After reading the mock transcript, participants answered questions concerning their beliefs of how credible each testimony was (defendant, victim, expert) on a 7-point Likert scale (1- Not at All to 7- Extremely). Participants were then asked to make a verdict choice by first indicating the degree to which they found the defendant guilty (1 – not at all guilty to 7 – definitely guilty). Participants were also asked to make a dichotomous choice between not guilty and guilty and to indicate how confident they were in their verdict choice (1 – not at all confident to 7 – very confident). Participants then responded to questions concerning potential treatment recommendations and amenability (4 questions), risk for future violence (1 question), and general recidivism of the defendant (2 questions) again using a 7-point Likert scale (Appendix B).



Participants were given the option to complete the survey in paper format or through an online survey (demographic information did not differ between the two methods). For the paper format, participants were run in small groups of 1-5 individuals. In both methods participants were instructed to imagine that they were actual jurors on a criminal case and were instructed to read the court transcript and respond to the various questionnaires. The entire session lasted approximately 45 minutes whether completed in person or online.




Preliminary Analyses

Before conducting any analyses, the data was examined for missing values, outliers, and violations to the assumptions necessary to conduct the MANOVAs. No missing values were found and sample sizes for each group were approximately equal. There was also no evidence of univariate or multivariate outliers. Multivariate normality was also ensured given that there are many more cases than dependant variables in each group and each group exceeded the recommended 20 degrees of freedom for error (Tabachnick & Fidell, 2007). Finally, the pattern of correlations between individual dependent variables was examined in order to ensure that it was appropriate for conducting the MANOVAs (i.e., non-significant or slightly negatively correlated).


In order to control for the possible confound of mock juror gender (given the unbalanced number of female to male mock jurors) and type of survey completed (paper versus online) preliminary analyses were conducted assessing the effect of these two variables on all dependent variables. No significant effects of mock juror gender or survey type were found for any of the outcome variables.


Principal components analysis (PCA).

There was great similarity in the questions concerning treatment (4 questions; e.g., likelihood of recommending treatment and likelihood a treatment benefit) and risk (3 questions; e.g., likelihood of future risk and likelihood of future criminal acts). The Pearson correlations among the 6 outcome variables ranged from .05 to .76 with 16 correlations > .20. Given these correlations and similar to the procedure used in Boccaccini and colleagues (2008), these outcome variables were subjected to a principle components analysis (PCA) with varimax rotation in order to examine whether the number of outcome variables could be reduced. A two-factor solution was chosen with items showing high loadings on one factor (>.67) and not the other (<.20). Only one item (how likely to recommend treatment?) did not clearly load onto either factor and was therefore removed from further analyses. The two-factor solution accounted for 76.3% of the variance in ratings. Composite variables were created by averaging the ratings for the items that loaded onto each variable. The first composite variable was labeled Treatment and consisted of 3 items pertaining to the overall benefit of treatment as well as the benefit of treatment specifically targeting violence and criminal behavior (Cronbach’s α = .87). The second composite variable was named Risk and consisted of the 3 items pertaining to risk of future violence, risk of future criminal behavior, and the threat posed to society (Cronbach’s α = .89).


Credibility Ratings

 A 3 (diagnosis: psychopathy vs. APD/CD vs. no diagnosis) x 2 (gender: male vs. female) x 2 (age: 30 vs. 15) between-subjects MANOVA with post hoc comparisons using Tukey’s honestly significant difference (HSD) and corresponding effect size (Cohen’s d) with 95% confidence interval was conducted on mock jurors’ ratings of the credibility of the victim, defendant, and expert witness. Means and standard deviations can be seen in Table 2. Only the effect of diagnosis was significant across all credibility outcomes accounting for 8% of the variability, Wilk’s Λ = .84, F(6, 466) = 7.06, p < .001, partial η2 =

.08. Significant main effects of diagnosis were found for the credibility of the victim, F(2, 235) = 4.89, p = .01, partial η2 = .04, the defendant, F(2, 235) = 13.98, p < .001, partial η2 =

.12, and the expert witness, F(2, 235) = 3.69, p = .03, partial η2 = .03, although the significant result for the credibility of the defendant accounted for more variability in credibility ratings than that of the other two significant results. No other main effects or interactions were significant.

Victim. Post hoc comparisons revealed a significant difference in mean victim credibility ratings between the psychopathy and no disorder groups, with a moderate effect size (p = .01; Cohen’s d = 0.48, 95% CI = .17, .78). When the defendant was described as a psychopath, mock jurors found the victim to be more credible than when the defendant was described as having no disorder. All other comparisons were non-significant with small effect sizes (psychopathy vs. APD/CD: d = .28, 95% CI = -.03, .59; APD/CD vs. no disorder: d = .20, 95% CI = -.11, .50).

Defendant. Mean credibility ratings for the defendant were significantly different between the psychopathy and no disorder conditions, showing a large effect (p < .001; Cohen’s d = -0.77, 95% CI = .46, 1.09) and between the APD/CD and no disorder conditions, showing a moderate effect (p = .001; Cohen’s d = -0.58, 95% CI = .27, .89). When the defendant was described as a psychopath or as APD/CD, mock jurors were less likely to find his/ her story credible compared to the defendant described as having no disorder. There was a small non-significant effect between psychopathy and APD/CD (d =.20, 95% CI = -.12, .51).

Expert. Mean credibility ratings of the expert witness were significantly different between the psychopathy and no disorder groups, showing a moderate effect (p = .02; Cohen’s d = -0.42; 95% CI = .11, .72). Mock jurors rated the expert witness as less credible when he was describing psychopathy symptoms compared to the description of no disorder. All other comparisons were non-significant with small effect sizes (psychopathy vs. APD/CD: d = .16, 95% CI = -.16, .37; APD/CD vs. no disorder: d = .26, 95% CI = -.05, .57).


[Insert Table 2]


Verdict Choice

 A 3 (diagnosis: psychopathy vs. APD/CD vs. no diagnosis) x 2 (gender: male vs. female) x 2 (age: 30 vs. 15) ANOVA with post hoc comparisons using Tukey’s HSD with corresponding effect size and 95% confidence interval was conducted on mock jurors’ guilty ratings of the defendant. A significant main effect was found for type of diagnosis accounting for 13% of the variability in guilty ratings, F(2, 235) = 17.88, p < .001, partial η2 = .13. No other main effects or interactions were significant. Post hoc comparisons indicated significant differences in verdict ratings between the psychopathy and no disorder condition, showing a large effect (p < .001; Cohen’s d = 0.88; 95% CI = .56, 1.20) and between the APD/CD and no disorder condition, showing a moderate effect (p < .001; Cohen’s d = 0.63; 95% CI = .32, .94). When the defendant was described as a psychopath or as having APD/CD, mock jurors gave higher guilt ratings (M = 4.64, SD = 1.33; M = 4.28, SD = 1.45 respectively) than when the defendant was described as having no disorder (M = 3.38, SD = 1.47). There was no difference in verdict ratings between the psychopathy and APD/CD conditions (d = .25, 95% CI = -.07, .56).

Logistic regression analysis was performed to predict the probability that a participant would choose a guilty verdict (0 = not guilty and 1 = guilty). The predictor variables were diagnosis (with no disorder as the reference category), age, and gender of the defendant. All interactions between the variables were included and all variables were simultaneously entered into the model. A test of the full model was significant, χ2(11, N = 247) = 45.13, p < .001, and the Hosmer and Lemeshow test revealed a good fit between the data and the model (goodness of fit χ2 = 0, df = 8, p = 1.0). The Wald test of significance revealed that only psychopathy and APD/CD diagnoses significantly predicted a guilty verdict. The adjusted odds ratio for diagnosis indicates that, holding all other variables constant, a defendant described as a psychopath is 7.5 times more likely to elicit a guilty verdict than when the defendant has no disorder, and an APD/CD defendant is 9 times more likely to elicit a guilty verdict than in the no disorder condition. The results from the logistic regression are presented in Table 3. Finally, how confident the juror was in their verdict decision was not significantly related to diagnosis, age, gender, or any of the interactions. The overall mean confidence in verdict was 4.73 (SD = 1.36).

[Insert Table 3]


Risk and Treatment

A 3 (diagnosis: psychopathy vs. APD/CD vs. no diagnosis) x 2 (gender: male vs. female) x 2 (age: 30 vs. 15) MANOVA with post hoc comparisons using Tukey’s HSD with corresponding effect size and 95% confidence interval was conducted for each of the composite variables, Risk and Treatment. Means and standard deviations can be found in Table 4. Only the effect of diagnosis was significant across both outcomes accounting for 12% of the variability, Wilk’s Λ = .78, F(4, 224) = 7.33, p < .001, partial η2 = .12. Follow- up analyses revealed that diagnosis was significant for Risk accounting for 19% of the variability, F(2, 113) = 13.14, p < .001, partial η2 = .19, but not significant for Treatment, F(2, 113) = 0.70, p = .50, partial η2 = .01. Post hoc comparisons showed a large significant effect between the psychopathy and no disorder condition (p < .001; Cohen’s d = 1.31, 95% CI = .77, 1.84) and between the APD/CD and no disorder condition (p < .001; Cohen’s d = 1.02; 95% CI = .48, 1.54) with mock jurors giving higher ratings of future risk to defendants described as psychopathic and as having APD/CD compared to defendants described as having no disorder. There was no difference between psychopathy and APD/CD (d = .28, 95% CI = -.07, .56).

[Insert Table 4]


Age and Gender

In order to further explore the non-significant findings concerning age and gender, the standardized mean differences (Cohen’s d) and corresponding 95% confidence intervals were calculated for each outcome variable (i.e., credibility ratings, verdict, Risk, and Treatment). Consistent with the previous analyses, standardized mean differences between male and female defendants were small and non-significant (range of Cohen’s d values = .01, .34) with confidence intervals overlapping zero. The same pattern of results was found for adult versus youth defendants (range of Cohen’s d values = .00 to .23 with confidence intervals overlapping zero). Given that Cohen’s d is a standardized metric independent of sample size, these results demonstrate that the null effects for age and gender are not likely due to study methodology.



The primary goal of this study was to assess the effect of diagnostic labels and traits on mock jurors’ perception of credibility, verdict choice, risk for violence and recidivism, and treatment amenability while also assessing the effects of age and gender of the defendant. This is the first labeling study to include a female defendant and to manipulate the defendant’s age in addition to including diagnostic information.

Diagnostic labels/traits affected ratings of credibility for the victim, defendant, and expert witness. Mock jurors were clearly affected by the expert witness testimony since they rated the defendant as less credible when he/she was described and labeled as a psychopath. Moreover, participants found the victim to be more credible in the psychopathy condition. Given that media portrayals of psychopaths emphasize their deceitful interpersonal style and their callous-unemotional traits (Stevens, 2008) it is not surprising that mock jurors ascribed similar traits to the defendant. In fact, an open-ended question asking for factors contributing to verdict choice indicated that participants in the psychopathy condition were more likely to doubt the defendant’s version of events. This finding is contrasted against the fact that the credibility of the expert witness was also lower in the psychopathy condition. This is an interesting finding considering the obvious effect of this same testimony on the credibility of the other two testimonies.

Consistent with our hypothesis, mock jurors gave the defendant significantly higher guilt ratings and were more likely to find the defendant guilty given a dichotomous choice when the defendant was diagnosed as a psychopath compared to no disorder. The transcript in the current study contrasted the victim’s version of events with the defendant’s.

Considering the credibility outcome, it is possible that the verdict choice stemmed from the fact that participants simply found the psychopathic defendant to be less credible than the victim. Follow-up analyses revealed a significant negative correlation between the credibility of defendant and the degree of guilt assigned (r = -.50; p < .001) preliminary support for this hypothesis. These observations raise questions as to when it is appropriate to introduce psychopathy evidence in a legal setting (Edens & Petrila, 2006). Although psychopathy evidence may be beneficial when assessing future risk for recidivism (consistent with the psychopathy literature), the probative value of psychopathy when considering guilt is not as well established (for a review see Lyon & Ogloff, 2000). In fact, the use of the psychopathy diagnosis within the CJS has been questioned on grounds of evidence admissibility and whether there is even appropriate scientific literature supporting the conclusions that are often made (e.g., notion that psychopaths cannot be treated or that treatment makes them worse; Edens & Petrial, 2006).

The remaining results replicated the findings from previous labeling studies: psychopathy (traits/label) was significantly related to increased ratings of risk (Edens et al., 2004, 2005; Jones & Cauffman, 2008; Murrie et al., 2007; Vidal & Skeem, 2007), there was no significant effect of treatment (Murrie et al., 2005, 2007; Rockett et al., 2007), and these results were consistent for both types of diagnoses indicating a general labeling effect rather than a specific effect of psychopathy (Edens et al., 2004, 2005; Murrie et al., 2005, 2007). Although the overall effect sizes are considered small by conventional standards, these types of effect sizes are quite common in psychological research (Cohen, 1988). The standardized mean differences between the levels of diagnosis were moderate to high, further supporting the negative effect of diagnosis on ratings of credibility, verdict, and future risk.

There were no significant main effects of defendant age or gender on any of the outcome variables. Regardless of diagnosis, mock jurors tended to be unaffected by these extralegal factors which is contrary to some studies showing that younger defendants (Bergeron & McKelvie, 2004; Smith & Hed, 1979) and female defendants (Heatherton & Beardsall, 1998; Pozzulo et al., 2010; Rogers & Davies, 1997) are treated more leniently by mock jurors. When faced with null findings, it is often suggested that post-hoc analyses should be conducted in order to ensure adequate power. Unfortunately, retrospective power analyses can be quite misleading given that observed power is directly related to p-values and the observed effect size (e.g., large p-values and small effect sizes contribute to lower power; see Nakagawa & Foster, 2004). Given the relationship between power, p-value, and effect size, observed power is always low for non-significant results regardless of the sample size used (Goodman & Berklin, 1994; Hoenig & Heisey, 2001). Due to these limitations, standardized mean differences with corresponding confidence intervals were reported rather than observed power (Cohen, 1988; Nakagawa & Foster, 2004). Consistent with the reported null findings, overall effect sizes and standardized mean differences for age and gender were small and non-significant. This indicates that these variables explain very little variability in mock juror decisions reported in the current study.



Although this study presents a number of interesting findings, there are a number of limitations that should be considered. The following discussion is limited to the transcript and sample. Although the use of short transcripts allows for the manipulation of key variables and the maintenance of internal validity, it does so at the cost of external validity. The present study attempted to overcome this limitation by providing a longer trial transcript. It is important to note that increasing the length of the transcript allows for participants to consider additional factors in their decision making other than the independent variables presented. This increase in variability may explain the relatively small effect sizes previously discussed. While considered small, the effect sizes are consistent with those reported in a similar study where the authors used a longer transcript (i.e., Pozzulo et al., 2010) and in psychology research in general (Cohen, 1988).

A second limitation of the transcript relates to the judge’s instructions to the participants. Although the judge cautioned the participants to view all information without bias, the participants were not instructed on rules of reasonable doubt. It is possible that more participants would have chosen a verdict of not guilty had they been reminded that a guilty verdict is only applicable if the juror is satisfied of the defendant’s guilt beyond a reasonable doubt. In order to increase the external validity of future studies, instructions specifying reasonable doubt as the burden of proof for a guilty verdict should be included.

In terms of the sample, participants in this study were primarily undergraduate students. A small number of community members was also included, however, analyses of both groups separately was not possible given how the data was collected. Few studies have examined whether a mock jury, comprised mostly of students, can accurately capture the nature of real-life juries, however, a review of the literature concluded that the majority of research has reported no significant differences between students and the general population (Bornstein, 1999).


Implications for the CJS

 The most consistent finding across all labeling research is that psychopathy evidence is associated with more punitive decision making. Although associating psychopathy with a greater likelihood of recidivism and violence is consistent with the psychopathy literature, this is only true when the diagnosis is accurately assigned. A potential problem with introducing an assessment of psychopathy in the judicial system occurs when the label is misused or when inappropriate conclusions concerning psychopathy are drawn (Lloyd, Clark, & Forth, 2010). With that said, several reviews have demonstrated problems in the application and interpretation of psychopathy evidence in real cases (Edens, 2001; Zamble & Forth, 1998). Edens (2001), for example, described a case where the expert witness did not have adequate information to administer the PCL-R and subsequently drew erroneous conclusions based on that assessment (e.g., low psychopathy score was evidence that the defendant had not committed the crime). Finally, several studies have also demonstrated a tendency of clinicians to be biased towards the side that retained them for the psychopathy evaluation (Murrie, Boccaccini, Caperton, & Rufino, 2012; Murrie, Boccaccini, Johnson, & Janke, 2008; Rufino, Boccaccini, Hawes, & Murrie, 2012). Based on this information, it is clear that before psychopathy evidence can be used within the CJS, the court must ensure that the evidence being presented is both valid and reliable.



Alterman, A. I., Cacciola, J. S., & Rutherford, M. J. (1993). Reliability of the Revised Psychopathy Checklist in substance abuse patients. Psychological Assessment: A Journal of Consulting and Clinical Psychology, 5, 442-448.

American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author

Bergeron, C. E., & McKelvie, S. J. (2004). Effects of defendant age on severity of punishment for different crimes. Journal of Social Psychology, 144, 75-90. doi: 10.3200/SOCP.144.1.75-90

Boccaccini, M. T., Murrie, D. C., Clark, J. W., & Cornell, D. G. (2008). Describing, diagnosing, and naming psychopathy: How do youth psychopathy labels influence jurors? Behavioral Sciences and the Law, 26, 487-510. doi: 10.1002/bsl.821

Bornstein, B. H. (1999). The ecological validity of jury simulations: Is the jury still out?

Caldwell, M. F., McCormick, D. J., Umstead, D., & Van Rybroek, G. J. (2007). Evidence of treatment progress and therapeutic outcomes among adolescents with psychopathic features. Criminal Justice and Behavior, 34, 573-587. doi:10.1177/0093854806297511

Caldwell, M. F., Skeem, J., Salekin, R., & Van Rybroek, G. (2006). Treatment response of adolescent offenders with psychopathy features: A 2-year follow-up. Criminal Justice and Behavior, 33, 571-596. doi:10.1177/0093854806288176

Chauhan, P., Reppucci, N. D., & Burnette, M. L. (2007). Application and impact of the psychopathy label to juveniles. International Journal of Forensic Mental Health, 6, 3- 14.

Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd Ed.). Erlbaum, Hillsdale.

Cox, M. S., DeMatteo, D. S., & Foster, E. E. (2010). The effect of the Psychopathy Checklist – Revised in capital cases: Mock jurors’ responses to the label of psychopathy. Behavioral Sciences and the Law, 28, 878-891. doi: 10.1002/bsl.958

DeMatteo, D., & Edens, J. F. (2006). The role and relevance of the Psychopathy Checklist- Revised in court: A case law survey of U.S. courts (1991-2004). Psychology, Public Policy, and Law, 12, 214-241. doi: 10.1037/1076-8971.12.2.214

Dolan, M., & Völlm, B. (2009). Antisocial personality disorder and psychopathy in women: A literature review on the reliability and validity of assessment instruments. International Journal of Law and Psychiatry, 32, 2-9. doi: 10.1016/j.ijlp.2008.11.002

Doren, D. M., & Yates, P. M. (2008). Effectiveness of gender offender treatment for psychopathic genderual offenders. International Journal of Offender Therapy and Comparative Criminology, 52, 234-245. doi:10.1177/0306624X07303914

D’Silva, K., Duggan, C., & McCarthy, L. (2004). Does treatment really make psychopaths worse? A review of the evidence. Journal of Personality Disorders, 18, 163-177.

Edens, J. F. (2001). Misuses of the Hare Psychopathy Checklist-Revised in court: Two case examples. Journal of Interpersonal Violence, 16, 1082-1093. doi:10.1177/088626001016010007

Edens, J. F., Buffington, J. K., Tomicic, T. L., & Riley, B. D. (2001). Effects of positive impression management on the psychopathic personality inventory. Law and Human Behavior, 25, 235-256.

Edens, J. F., & Campbell, J. S. (2007). Identifying youths at risk for institutional misconduct: A meta-analysis of the Psychopathy Checklist measures. Psychological Services, 4, 13-27.

Edens, J. F., Campbell, J. S., & Weir, J. M. (2006). Youth psychopathy and criminal recidivism: A meta-analysis of the Psychopathy Checklist measures. Law and Human Behavior, 31, 53-75. doi: 10.1007/s10979-006-9019-y

Edens, J. F., Colwell, L. H., Desforges, D. M., & Fernandez, K. (2005). The impact of mental health evidence on support for capital punishment: Are defendants labeled psychopathic considered more deserving of death? Behavioral Sciences and the Law, 23, 603-625. doi: 10.1002/bsl.660

Edens, J. F., Desforges, D. M., Fernandez, K., & Palac, C. A. (2004). Effects of psychopathy and violence risk testimony on mock juror perceptions of dangerousness in a capital murder trial. Psychology, Crime, and Law, 10, 393-412. doi: 10.1080/10683160310001629274

Edens, J. F., Guy, L. S., & Fernandez, K. (2003). Psychopathic traits predict attitudes toward a juvenile capital murderer. Behavioral Sciences and the Law, 21, 807-828. doi: 10.1002/bsl.567

Edens, J. F., & Petrila, J. (2006). Legal and ethical issues in the assessment and treatment of psychopathy. In C. J. Patrick (Ed.), Handbook of psychopathy (pp. 573-588). New York: Guilford Press.

Goodman, S. N., & Berklin, J. A. (1994). The use of predicted confidence intervals when planning experiments and the misuse of power when interpreting results. Annals of Internal Medicine, 121, 200-206.

Grann, M. (2000). The PCL-R and gender. European Journal of Psychological Assessment, 16, 147-149.

Hare, R. D. (1998). Psychopaths and their nature: Implications for the mental health and criminal justice systems. In T. Millon, E. Simonsen, M. Birket-Smith, & R. D. Davis (Eds.), Psychopathy: Antisocial and violent behavior (pp. 188-212). New York, NY: Guilford Press.

Hare, R. D. (2001). The Hare Psychopathy Checklist-Revised. Toronto, ON, Canada: Multi- Health Systems.

Hare, R. D. (2003). The Hare Psychopathy Checklist-Revised, 2nd edition. Toronto, ON, Canada: Multi-Health Systems.

Harris, G. T., & Rice, M. E. (2006). The treatment of psychopathy. In C. J. Patrick (Ed.),

Handbook of psychopathy (pp. 555-572). New York: Guildford.

Heatherton, J., & Beardsall, L. (1988). Decisions and attitudes concerning sexual abuse: Does the gender of the perpetrator make a difference to child protection professionals? Child Abuse and Neglect, 22, 1265-1283.

Hemphill, J. F., Hare, R. D., & Wong, S. (1998). Psychopathy and recidivism: A review. Legal and Criminological Psychology, 3, 139-170.

Hoenig, J. M., & Heisey, D. M. (2001). The abuse of power: the pervasive fallacy of power calculations for data analysis. The American Statistician, 55, 19-24.

Jones, S., & Cauffman, E. (2008). Juvenile psychopathy and judicial decision making: An empirical analysis of an ethical dilemma. Behavioral Sciences and the Law, 26, 151- 165. doi: 10.1002/bsl.792

Leistico, A. R., Salekin, R. T., DeCoster, J., & Rogers, R. (2008). A large-scale meta- analysis relating the Hare measures of psychopathy to antisocial conduct. Law and Human Behavior, 32, 28-45. doi: 10.1007/s10979-007-9096-6

Lilienfeld, S. O. (1998). Methodological advances and developments in the assessment of psychopathy. Behavior Research and Therapy, 36, 99-125.

Lloyd, C. D., Clark, H. J., & Forth, A. E. (2010). Psychopathy, expert testimony, and indeterminate sentences: Exploring the relationship between Psychopathy Checklist- Revised testimony and trial outcome in Canada. Legal and Criminological Psychology, 15, 323-339. doi: 10.1348/135532509X468432

Loeffler, R. L., & Lawson, T. J. (2002). Age and occupational status of defendant in relation to mock jurors sentencing recommendations. Current Psychology, 21, 289- 292. doi: 10.1007/s12144-002-1019-6

Lyon, D. R., & Ogloff, J. R. P. (2000). Legal and ethical issues in psychopathy assessment.

In C. Gacono (Ed.), The clinical and forensic assessment of psychopathy (pp. 139– 173). Mahwah, NJ: Erlbaum.

MacNeil, B. M., & Holden, R. R. (2006). Psychopathy and the detection of faking on self- report inventories of personality. Personality and Individual Differences, 41, 641- 651.

Murrie, D. C., Boccaccini, M. T., Johnson, J. T., & Janke, C. (2008). Does interrater (dis)agreement on Psychopathy Checklist scores in sexually violent predator trials suggest partisan allegiance in forensic evaluations? Law and Human Behavior, 32, 352-362.

Murrie, D. C., Boccaccini, M. T., McCoy, W., & Cornell, D. G. (2007). Diagnostic labeling in juvenile court: How do descriptions of psychopathy and conduct disorder influence judges? Journal of Clinical Child and Adolescent Psychology, 36, 228-241.

Murrie, D. C., Boccaccini, M. T., Caperton, J. & Rufino, K. (2012). Field validity of the Psychopathy Checklist–Revised in sex offender risk assessment. Psychological Assessment 24(2), 524-529. doi: 10.1037/a0026015

Murrie, D. C., Cornell, D. G., & McCoy, W. K. (2005). Psychopathy, conduct disorder, and stigma: Does diagnostic labeling influence juvenile probation officer recommendations? Law and Human Behavior, 29, 323-342. doi: 10.1007/s10979-005- 2415-x

Nakagawa, S., & Foster, T. M. (2004). The case against retrospective statistical power analyses with an introduction to power analysis. Acta Ethol, 7, 103-108.

O’Neill, M. L., Lidz, V., & Heilbrun, K. (2003). Adolescents with psychopathic characteristics in a substance abusing cohort: Treatment and process outcomes. Law and Human Behavior, 27, 299-313. doi: 0147-7307/03/0600-0299/1

Petrila, J., & Skeem, J. L. (2003). An introduction to the special issues on juvenile psychopathy and some reflections on the current debate: Juvenile psychopathy: The debate. Behavioral Sciences and the Law, 21, 689-694. doi: 10.1002/bsl.569

Pozzulo, J. D., Dempsey, J., Maeder, E., & Allen, L. (2010). The effects of victim gender, defendant gender, and defendant age on juror decision making. Criminal Justice and Behavior, 37, 47-63. doi: 10.1177/0093854809344173

Rockett, J. L., Murrie, D. C., & Boccaccini, M. (2007). Diagnostic labeling in juvenile justice settings: Do psychopathy and conduct disorder findings influence clinicians? Psychological Services, 4, 107-122.

Rogers, P., & Davies, M. (2007). Perceptions of victims and perpetrators in a depicted child sexual abuse case: Gender and age factors. Journal of Interpersonal Violence, 22, 566-doi: 10.1177/0886260506298827

Rogers, R., Vitacco, M. J., Cruise, K. R., Sewell, K. W., & Neumann, C. S. (2002).

Screening for adolescent psychopathy among at-risk youth: Initial validation of the survey of attitudes and life experiences. Assessment, 9, 343-350. doi:10.1177/1073191102238154

Rufino, K. A., Boccaccini, M. T., Hawes, S. M., Murrie, D. C. (2012). When experts disagreed, who was correct? A comparison of PCL-R scores from independent raters and opposing forensic experts. Law and Human Behavior (Feb 20, 2012). doi: 10.1037/h0093988

Salekin, R. T. (2002). Psychopathy and therapeutic pessimism: Clinical lore or clinical reality? Clinical Psychology Review, 22, 79-112.

Salekin, R., Rogers, R., & Machin, D. (2001). Psychopathy in youth: Pursuing diagnostic clarity. Journal of Youth and Adolescence, 30, 173-195.

Salekin, R., Rogers, R., Ustad, K. L., & Sewell, K. (1998). Psychopathy and recidivism among female inmates. Law and Human Behavior, 22, 109-128.

Smith, E. D., & Hed, A. (1979). Effects of offenders’ age and attractiveness on sentencing by mock juries. Psychological Reports, 44, 691-694.

Spain, S., Douglas, K., Poythress, N. G., & Epstein, M. (2004). The relationship between psychopathic features, violence and treatment outcome: The comparison of three youth measures of psychopathic features. Behavioral Science and the Law, 22, 85-102. doi: 10.1002/bsl.576

Stevens, A. (2008). Psychopathy in the media: A content analysis. (Master’s thesis). Retrieved from Dissertations and Theses: Full text.

Tabachnick, B. G., & Fidell, L. S. (2007). Using multivariate statistics (5th Ed.). Pearson Education Inc.

Verona, E., Sadeh, N., Javdani, S. (2010). The influences of gender and culture on child and adolescent psychopathy. In R. T. Salekin and D. R. Lynam (Eds.), Handbook of child and adolescent psychopathy (pp. 317-342). New York, NY: Guilford Press.

Vidal, S., & Skeem, J. L. (2007). Effect of psychopathy, abuse, and ethnicity on juvenile probation officers’ decision-making and supervision strategies. Law and Human Behavior, 31, 479-498. doi: 10.1007/s10979-006-9077-1

Viljoen, J. L., McLachlan, K., & Vincent, G. M. (2010). Assessing violence risk and psychopathy in juvenile and adult offenders: A survey of clinical practices. Assessment, 17, 377-95.

Vitale, J. E., Smith, S. S., Brinkley, C. A., & Newman, J. P. (2002). The reliability and validity of the Psychopathy Checklist-Revised in a sample of female offenders.

Criminal Justice and Behavior, 29, 202-231. doi:10.1177/0093854802029002005 Walsh, T., & Walsh, Z. (2006). The evidentiary introduction of Psychopathy Checklist-

Revised assessed psychopathy in U.S. Courts: Extent and appropriateness. Law and Human Behavior, 30, 493-507. doi: 10.1007/s10979-006-9042-z

Walters, G. D. (2003a). Predicting criminal justice outcomes with the Psychopathy Checklist and Lifestyle Criminality Screening Form: A meta-analytic comparison. Behavioral Sciences and the Law, 21, 89-102. doi: 10.1002/bsl.519

Walters, G. D. (2003b). Predicting institutional adjustment and recidivism with the psychopathy checklist factor scores: A meta-analysis. Law and Human Behavior, 27, 541-558. doi: 0147-7307/03/1000-0541/1

Widiger, T. A. (2006). Psychopathy and DSM-IV psychopathology. In C. J. Patrick (Ed.), Handbook of Psychopathy (pp. 156-171). New York, NY: Guilford Press.

Widiger, T. A., & Corbitt, E. M. (1995). Antisocial personality disorder. In J. Livesley (Ed.), The DSM-IV personality disorder (pp.103-126). New York, NY: Guilford Press.

Zinger, I., & Forth, A. (1998). Psychopathy and Canadian criminal proceedings: The potential for human rights abuses. Canadian Journal of Criminology, 40, 237-276.



Appendix A


Psychopathy condition

Court-Appointed Psychologist: During the interview I found Philip/Diane to be superficial and insincere. Phillip/Diane consistently tries to charm, con, and manipulate others to obtain what he/she wants. He/She has no empathy for Mr./Mrs. Marlowe and refuses to take responsibility for his/her actions. I find him/her to be both impulsive and irresponsible in his/her behaviors lacking any realistic long-term plans. In my professional opinion, Phillip/Diane is a psychopath. OR


Antisocial Personality Disorder condition

Court-Appointed Psychologist: During the interview I found Phillip/Diane to be aggressive and agitated. He/she seemed to get bored with the interview and responded with anger. Phillip/Diane has had recurring difficulties with the law and has a tendency of violating the rights and boundaries of others. He/She has no remorse for Mr. /Mrs. Marlowe or others he/she may hurt. Phillip/Diane has an antisocial personality disorder.



Conduct Disordered condition

Court-Appointed Psychologist: During the interview, I discovered that Phillip/Diane has a persistent pattern of behavior in which he/she violates societal norms. Phillip/Diane has a history of bullying. He/She threatens to harm or intimate others. He /She initiates fights at school and has been caught destroying public property. He/She also lies in order to get what he/she wants.

This behavior has caused significant impairment in Phillip/Diane’s social and academic functioning. In my professional opinion, Phillip/Diane has a conduct disorder.



No Diagnosis

Court-Appointed Psychologist: During the interview, I found Phillip/Diane to be an earnest young man/woman. He/She was forthright and candid, providing careful and thorough answers. He/She was visibly upset about the incident and clearly showed empathy for Mr./Mrs. Marlowe. In my professional opinion, Phillip/Diane does not have any signs of a clinical diagnosis.



Appendix B


  1. How likely are you to recommend treatment for the defendant?


  1. How much would the defendant benefit from treatment?


  1. How useful would a treatment program aimed at reducing violence be for the defendant?


  1. How useful would any treatment program aimed at reducing criminal behavior be for the defendant?


  1. How high is the defendant’s risk for future violence?


  1. How high is the defendant’s risk for future criminal acts?


  1. How likely is it that the defendant poses a threat to society?




Leave a Reply

%d bloggers like this: