Venirepersons's Attitudes toward the Insanity Defense...

Venirepersons's Attitudes toward the Insanity Defense: Developing, Refining, and Validating aScaleAuthor(s): Jennifer L. Skeem, Jennifer Eno Louden, Jennee EvansSource: Law and Human Behavior, Vol. 28, No. 6 (Dec., 2004), pp. 623-648Published by: SpringerStable URL: http://www.jstor.org/stable/4141752Accessed: 12/08/2010 21:30

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Law and Human Behavior, Vol. 28, No. 6, December 2004 (@ 2004) DOI: 10.1007/s10979-004-0487-7

Venirepersons's Attitudes Toward the Insanity Defense: Developing, Refining, and Validating a Scale

Jennifer L. Skeem,1,2 Jennifer Eno Louden,' and Jennee Evans'

Given the prevalence and predictive strength of negative attitudes toward the insanity defense, we conducted three studies with 426 venirepersons to develop an understanding and a measure of public attitudes toward the insanity defense. In these studies, we developed, iteratively refined, and cross-validated the insanity defense attitude-revised (IDA-R) scale. The results suggest that IDAs are underpinned by one's degree of (a) orientation toward strict liability, and (b) concern about perceived injustice and danger associated with the defense. The IDA-R assesses these two-dimensions with good internal consistency, convergent and divergent validity, and predictive utility. The IDA-R's predictive utility generalizes across jurisdictions and manipulation of case facts. Theoretical and practical implications for research and for identifying impartial jurors at voir dire are discussed.

KEY WORDS: insanity defense; venirepersons; jurors.

A juror's task is to reach a legally appropriate verdict by applying legal criteria to a fair evaluation of the evidence presented at trial (Penrod & Heuer, 1997; Smith, 1991; Wainwright v. Witt, 1985). The legal system assumes that, given procedural safeguards, jurors function as blank slates who perform this task in a wholly evidence-driven fashion (Finkel, 1995; Smith, 1991). However, substantial research in social cognition indicates that people are not blank slates: they have knowledge "structures" that summarize their past experience and guide their future behavior (see also Fiske, 1993; Schneider, 1991, p. 533), including their legal decision- making. Mock jurors' attitudes about case-relevant topics and their stereotypes about offenses and offenders have been shown to substantially influence their verdicts (Moran, Cutler, & DeLisa, 1994; Pennington & Hastie, 1986; Smith, 1991, 1993; Stalans, 1993), even when they are specifically instructed to set them aside (see English & Sales, 1997; Smith, 1993).

1University of Nevada, Las Vegas, Nevada. 2To whom correspondence should be addressed at Department of Psychology, University of Nevada, Las Vegas, Box 455030, 4505 Maryland Parkway, Las Vegas, Nevada 89154-5030; e-mail: [email protected].

623

0147-7307/04/1200-0623/1 ? 2004 Springer Science+Business Media, Inc.

624 Skeem, Louden, and Evans

Fair jury trials are contingent upon the selection of jurors who can apply the law without undue bias (Dressler, 1991). Thus, the legal system has developed procedural safeguards designed to ensure legally appropriate jury verdicts. Prior to trial, the court conducts a voir dire to examine prospective jurors' attitudes and beliefs. A

juror is excused from jury service if her state of mind in reference to any person or issue involved in a case might substantially impair her performance of her duties as

juror (Adams v. Texas, 1980), such as following judicial instruction on the law (see Dillehay & Sandys, 1996).

Based on its pivotal role in protecting a fundamental constitutional right, voir dire is "perhaps the most important stage of any trial" (Dayan, Mahler, & Widenhouse, 1989, p. 191). However, voir dire often falls short of its purpose. Given their broad discretion in most cases, judges are increasingly conducting "streamlined" voir dire examinations that limit attorneys' participation and may be of in- sufficient scope to reveal juror bias (see Johnson & Haney, 1994, p. 488). However, even when attorneys are allowed to participate in voir dire, they often fail to iden-

tify jurors biased against their side (Hastie, 1991; compare Johnson & Haney, 1994; MacCoun, 1989). Attorneys often rely upon "stereotypic rules of thumb" to identify bias based on nonspecific demographic or attitudinal variables that do not predict verdicts well (Abbot, Hall, & Linville, 1993; Hastie, Penrod, & Pennington, 1983; as cited in Kassin & Wrightsman, 1983; Kassin & Wrightsman, 1994; MacCoun, 1989; Zeisel, 1977). Thus, juror bias may often go unnoticed during voir dire and influence case judgments and verdicts.

JUROR BIAS IN INSANITY DEFENSE CASES

Ineffective detection of juror bias poses a particular threat in cases where the

insanity defense is raised. Insanity is a defense for acquittal based on the defendant's

inability to appreciate or control his actions because of mental illness or defect

(Appelbaum, 1994). It is a controversial topic with strong moral-political implications. Although public opinion surveys and empirical studies sometimes find support for the abstract rationale of the insanity defense, they consistently unveil strong negative attitudes toward the defense (Ellsworth, Bukaty, Cowan, & Thompson, 1984; Golding, 1992; Hans, 1986; Hans & Slater, 1984; Homant & Kennedy, 1987; Jeffrey & Pasewark, 1983; Pasewark & Seidenzahl, 1979; Roberts & Golding, 1991; Roberts, Golding, & Fincham, 1987). For example, in a large survey (Hans, 1986), 78% of respondents believed the insanity defense was sometimes justified. Never- theless, about half of respondents believed the defense should be abolished, and

virtually all believed that it required substantial reform. Results across studies reflect a primary concern that the insanity defense is a

frequently abused "loophole" in the law that allows many guilty criminals to escape punishment (Golding, 1992; Perlin, 1994, Chapter 5; Silver, Circione, & Steadman, 1994). This myth associated with inaccurate knowledge (see Finkel, 1995, p. 268; Golding, 1992; Perlin, 1994, Chapters 3 & 5). The public grossly overestimates the number of defendants who enter insanity pleas and are acquitted by reason of insanity and underestimates the degree of confinement associated with insanity acquittals

Insanity Defense Attitudes 625

(Hans, 1986; Pasewark, 1981; Silver et al., 1994). Even after being provided with correct information about such issues, many individuals maintain their misconcep- tions (approximately 50%, Jeffrey & Pasewark, 1984), perhaps because they are associated with negative attitudes that bias "every step of the information process- ing sequence" (see also Eagly & Chaiken, 1993; Eagly & Mladinic, 1989; Olson & Zanna, 1993, p. 129). In short, negative attitudes and the myths with which they are associated are not only prevalent but are also often inflexible.

Especially troubling is the robust finding that attitudes toward the insanity defense exert considerable influence on mock jurors' verdicts in insanity cases (Bailis, Darley, Waxman, & Robinson, 1995; Cutler, Moran, & Narby, 1992; Ellsworth et al., 1984; Homant & Kennedy, 1987; Roberts & Golding, 1991; Roberts et al., 1987). For instance, Roberts & Golding (1991) found that jurors' attitudes toward the insan-

ity defense, particularly their opinions about the relevance of a defendant's mental state to his blameworthiness, were more strongly associated with their verdicts than were manipulations of case facts (e.g., the defendant's delusionality and planfulness) and verdict categories. Thus, juror's verdicts may depend more upon their attitudes and opinions than on case facts and court instruction.

In keeping with this premise, mock jurors often fail to apply judicial instruction on legal definitions of insanity in rendering verdicts (Finkel, 1989, 1991; Finkel, Shaw, Bercaw, & Koch, 1985; Ogloff, 1991; Ogloff, Schweighofer, Turnbull, & Whittemore, 1992; Simon, 1967). In fact, it often makes no difference whether jurors are given any test or not: mock jurors who receive no insanity test instructions or who are explicitly told to use their own "best lights" to decide the case

produce verdict patterns similar to those of mock jurors who receive various in-

sanity test instructions (Finkel, 1989; Finkel & Handel, 1988; Ogloff, 1991; Simon, 1967).

Thus, negative attitudes toward the insanity defense are prevalent, often inflexible, and relatively influential on case judgments and verdicts. Because a defendant cannot obtain a fair trial if some of the jurors impaneled are unable to entertain his or her legally recognized plea of insanity, it is crucial to develop an understanding of the nature of attitudes against the insanity defense and a valid means of assessing them.

IDENTIFYING BIAS IN INSANITY DEFENSE CASES

To date, there have been few attempts to deconstruct attitudes toward the in-

sanity defense and no attempts to systematically validate a measure of these attitudes. Such a measure would be useful for future research on jury decision-making, and for helping to identify impartial jurors during the voir dire process. Most studies have attempted to measure insanity defense attitudes (IDAs) based on single evaluative questions (Cutler et al., 1992; Ellsworth et al., 1984; Homant & Kennedy, 1987; Jeffrey & Pasewark, 1984; Tygart, 1992). As several authors have noted, single item scales are highly prone to error and inadequately represent the constructs they are designed to measure (see Abelson, 1992; Himmelfarb, 1993; Proctor, 1993). Although two groups of investigators (Hans, 1986; Roberts & Golding, 1991;


Roberts et al., 1987) have developed more sophisticated measures of IDA, their psychometric properties have not been systematically refined.

First, Hans (1986) developed the Insanity Defense Support (IDS) Scale, which consists of 16 statements that respondents rate on a four-point Likert scale (strongly agree to strongly disagree). Factor analysis revealed five factors that accounted for over 60% of the total variance. These factors were named (a) punishment, or the extent to which the criminally insane should be punished, (b) perceived danger associated with having an insanity defense, (c) perceived injustice associated with the defense, (d) psychiatric treatment and its effectiveness, and (e) the effectiveness of insanity defense procedures (Hans, 1986). Scores on each of these factors significantly predicted respondents' reported "overall support" for the insanity defense moderately well (betas ranged from .13 to .28). No data on reliability, cross-structure validity, or predictive utility for verdicts have been published.

Second, Roberts and colleagues (1987) created a 13-item questionnaire that respondents rated using a seven-point Likert scale (strongly disagree to strongly agree). A principal component (PrC) analysis suggested a four component structure, and one of the components (logic ofthe insanity defense) significantly predicted mock jurors' case verdicts, even after controlling for differences in case facts (i.e., the defendant's mental disorder and planfulness). Building on this scale, Roberts and Golding (1991) developed a 20-item measure. A PrC analysis of this measure suggested a four component structure that included (a) a strict liability orientation, or the extent to which mental state is irrelevant to blame and the imposition of punishment, (b) detention concerns about individuals acquitted by reason of insanity, (c) insanity irrelevant to guilt or beliefs about whether guilt applies to insane persons, and (d) death penalty attitudes. The vast majority (95%) of the items on this measure significantly discriminated between mock jurors who deemed the defendant NGRI and those who found him guilty or guilty but mentally ill (which functionally is no more than a guilty plea). Moreover, each of the four components added incremental utility in predicting verdicts after accounting for jurors' basic case judgments and variation in facts of the case (e.g., planfulness, delusional content).

To date, then, two multiple-item measures of IDAs have been created. These measures appear to share two important dimensions: (a) rejection or endorsement of the underlying logic of the insanity defense ("punishment," "pro-con logic of the insanity defense," "strict liability"); and, (b) degree of concern about community safety and the detention of insanity acquittees ("perceived danger," "detention concerns"). However, their actual degree of overlap and coverage of the full domain of IDAs is unclear. Although these measures predict jurors' overall orientation toward the insanity defense and case verdicts, their psychometric properties have not been systematically studied.

THE PRESENT RESEARCH

Given the prevalence of negative attitudes toward the insanity defense and their strength in predicting case judgments, we conducted a series of studies that


were designed to (a) develop an understanding of core dimensions of contemporary attitudes toward the insanity defense, and (b) validate a measure of these dimensions. By doing so, we hoped to improve the precision of future research on jurors' decisional processes in insanity cases, and to aid legal professionals in identifying im-

partial jurors at voir dire. We addressed these aims in three studies conducted with former prospective jurors (venirepersons) in two jurisdictions. In the first study, we

developed items to represent the domain of IDAs as fully as possible, administered them to a venireperson sample along with a measure of social desirabilty, and used the results to refine the scale. In the second study, we administered the revised scale to an independent sample of venirepersons along with theoretically relevant measures to validate and further refine the scale. In the third study, we cross-validated the final scale with a venireperson sample from a different state.

Study 1: Item Development

In the first study, we developed items for a draft measure of IDAs that reflected a range of contemporary opinions. These items were administered to a sample of

venirepersons to select items that had relatively high response variability, item-total correlations, and factor loadings, and relatively low factorial complexity and correlations with socially desirable response sets.

METHOD

Participants

Participants were 178 community citizens who were called to appear in one of 18 randomly selected criminal or civil cases of the Third District Court, which

represents approximately 40% of Utah's population (Utah Population Estimates Committee, 1998). Most (95%) of the study participants were White (2% were

Hispanic, 2% East Indian, 1% Asian). Fifty-six percent of participants were female.

Participants' average age was 46 years (SD = 12.59), and their average educational level was just below a bachelor's degree (M = 15 years, SD = 2.73). Only 29% of

participants actually served as jurors on the index case. Of the 409 venirepersons called for the selected cases and invited to take part

in the study, 44% returned the study measures. Notably, venirepersons were much more likely to participate when invited in person (in court or by phone; 58% participated) than when invited by mail (10% participated). Study participants did not differ from nonparticipants with respect to gender (X2[1, N = 404] = 0.13, p = .72]) or juror/nonjuror status (X2[1, N = 409] = .25, p = .61). Although participants were

significantly older than nonparticipants (t[388] = -2.85, p = .01), the magnitude of this difference was small: participants' average age was 46 years (SD = 12.6) and

nonparticipants' was 42 years (SD = 14.6). Because nonparticipants' race and educational level were not available, they were estimated from county census statistics (Census of Population and Housing, 1990; Utah Department of Employment Secu- rity, 1998), which probably overestimate the proportion of racial minorities found


in jury pools and underestimate the educational level (see Abbott, Hall, & Linville, 1993; Bueker, 1997). This stringent test of the sample's representativeness indicates that study participants attained higher levels of education than census estimates, X2(4, N = 350) = 43.73, p < .001, and were more likely to be White (X2[5, N = 354] = 15.76, p < .001: 87% of county residents, and 95% of study participants were White).

Measures

Insanity Defense Attitudes

The initial version of the IDAs scale consisted of 38 items. Of these, 35 were core items designed to tap the four dimensions explained later, and 3 were general opinion items (e.g., "the insanity defense needs a lot of reform"). The core items of the IDA were selected from a much larger pool of items developed from three sources of information: (a) popular press insanity defense articles published in na- tional (e.g., USA Today, Newsweek, People Weekly, Ladies' Home Journal, Time) and local (e.g., newspapers) sources, (b) items from past public opinion pools and measures of IDAs that strongly predicted mock jurors' verdicts (e.g., Cutler et al., 1992; Hans, 1986; Jeffrey & Pasewark, 1983; Roberts & Golding, 1991; Roberts et al., 1987;), and (c) subjective factors cited by mock jurors as important to their verdicts in insanity cases (Finkel & Handel, 1989; Ogloff, 1991).

The 35 items selected were designed to represent four broad domains: (a) opinions that mental disorder implies reduced capacity or that defendants are responsible for their crimes regardless of whether they are mentally disordered (i.e., strict liability), (b) concerns about the detention and dangerousness of insanity acquittees, (c) perceptions that the insanity defense is unjust (e.g., a "loophole" in the law, a rich person's defense), and (d) opinions that defendants should be held accountable for their crimes if responsible for their compromised mental state at the time of the offense (e.g., if they refuse to take medication or attend therapy). At least 5 items were written for each hypothesized domain, approximately half of which were reverse-keyed to avoid response biases. Marker items were included for each domain to aid in interpreting factor analyses (Nunnally & Bernstein, 1994). Notably, reading ease analyses were used to develop items that could be easily understood by individuals with a high school education.

Social Desirability

The Marlowe-Crowne Social Desirability Scale (MCSD, Crowne & Marlowe, 1960) was also administered to participants to identify and eliminate items on the IDA that were highly associated with social desirability. The MCSD is a 33-item, true-false questionnaire that measures participants' need "to obtain approval by responding in a culturally appropriate and acceptable manner" (Crowne & Marlowe, 1960, p. 353). The MCSD items are keyed for behaviors that are socially desirable but unlikely to occur. The scale is internally consistent and predicts individuals' ten- dency to describe unpleasant tasks in favorable terms (Crowne & Marlow, 1960; Marlowe & Crowne, 1961).


Procedure

Prospective participants were invited to take part in the study either in court on their first day of court service or by telephone or postcard 2-4 months following their service. Venirepersons who agreed to take part in the study were mailed the study materials and, if necessary, contacted by telephone 2 and 4 weeks later and asked to return their responses. Although this method made it impossible to moni- tor participants while they completed the measures, it was the only court-approved method available for conducting this study using actual venirepersons. Provisions were made to ensure that participants' responses were kept anonymous (e.g., their responses were returned in envelopes with return address labels that were detached prior to scrambling and then opening envelopes; names did not appear on any of the study materials). The order of the measures (IDA and MCSD) was counterbalanced. Participants were paid $5.

RESULTS AND DISCUSSION

Factor Analysis and Scale Refinement

Prior to analysis, squared multiple correlations (SMCs) were computed to identify outlying items. Based on this analysis, two outlying items were deleted because they were poorly associated with the remaining items, leaving a total of 33 items for analysis. To assess the structure of the IDA, a PrC analysis was performed on the correlation matrix for these items. Three factors that accounted for 49% of the variance in the IDA items were extracted from the final PrC. Because the first two components were moderately correlated (r = .40), and there was no need to generate orthogonal component scores, an oblique rotation (direct oblimin), was performed to improve the interpretability of the solution. This rotation appeared adequate, based on such factors as Thurstone's criteria and the interpretability of the solution.

The first component, labeled "strict liability," reflects the extent to which individuals believe that mental illness is associated with reduced capacity for rational decision making and control (e.g., severe mental illness can impair people's ability to make logical choices and control themselves), and that reduced capacity isrelevant to the issue of criminal responsibility (e.g., a defendant's degree of insanity is irrelevant: if he commits the crime, then he should do the time). The second component, labeled "injustice and danger," reflects the extent to which individuals perceive that the insanity defense is misused (e.g., perfectly sane killers can get away with their crimes by hiring high-priced lawyers and experts who misuse the insanity defense"), and jeop- ardizes public safety (e.g., the insanity defense returns disturbed, dangerous people to the streets). Although this second component included items that were designed for two separate factors, the emergence of a single component was consistent with Hans' (1986) finding that similar items tended to load complexly on factors labeled "perceived danger" and "perceived injustice." The third component, labeled "treatment refusal," included all items designed to assess opinions that people should be held responsible if accountable for their compromised mental condition at the time of an offense (e.g., "if a mentally ill person starts refusing psychiatric treatment and his condition gets worse, he should not be held accountable... ").


These component analyses were designed not only to assess the extent to which the IDA's structure was consistent with its hypothesized dimensions, but also to refine the scale. Thus, the IDA items were examined to determine which should be retained, modified, or deleted. Items that tended to load by themselves in analyses that permitted several factors, and items in the final solution with component loadings <.5 or with high factorial complexity were revised (n = 8) or deleted (n = 1, item 26).

Further Scale Refinement

Response Variability

Next, IDA items with little or no response variability were revised or deleted. Because all five of the items that loaded on the "treatment refusal" component were extremely peaked and skewed, they were deleted. Regardless of their orientation, people apparently agree that refusing treatment invokes greater personal responsibility for one's actions. One additional item with an extremely peaked and nega- tively skewed distribution was deleted.

Internal Consistency

Prior to revision, the entire IDA scale had modest internal consistency (a = .47), due in part to its multidimensional structure. Item-total correlations and SMCs were computed to determine the degree of relationship between the scale and each item. Based on these analyses, two items with item-total correlations or SMCs of <.35 were deleted from the scale (items 18 and 33).

Association with Social Desirability

Only one IDA item was significantly (p < .01) associated with social desirability, as measured by the MCSD. However, because this item was a marker variable for the "injustice-danger" component, it was revised rather than deleted. The correlations among IDA and MCSD items were likely attenuated by poor reliability: the internal consistency of the MCSD in this sample was very poor (Kuder-Richardson = .32).

The Insanity Defense Attitude-Revised

In total, nine items were revised and nine deleted from the IDA. The modified version of the IDA consisted of 26 core items, but 9 of these were considered provisional because they had poor psychometric characteristics and had been revised in an attempt to address these limitations. These 26 items seemed to tap two dimensions: "strict liability," and "injustice and danger." Three additional items were retained from the IDA to assess general opinions. This modified measure was refined and developed into the Insanity Defense Attitude-Revised (IDA-R) in the second study.


Study 2: Measure Validation and Refinement

The second study was designed to further refine and assess the psychometric properties of the IDA, including its construct validity and strength in predicting insanity case judgments. In this study, an independent sample of venirepersons completed the modified IDA along with several other measures relevant to

testing its convergent and divergent validity. To assess the IDA's predictive util-

ity, these venirepersons also rendered case judgments based on an insanity case

vignette. Contravening conventional wisdom about test development, the convergent

and divergent validity of the IDA-R were tested based on a single method (self- report). This is because (1) the IDA-R was developed to identify bias using a self-

report format that could easily be used at voir dire, and (2) a change of method can change what is being measured (Dawis, 1987; Nunnally & Bernstein, 1994). Be- cause the relative relationships between the IDA-R and the convergent and diver-

gent measures are being compared, the effects of shared method variance should be

partially controlled.

METHOD

Participants

Participants were 135 former venirepersons called for nine randomly selected criminal and civil cases of the Third District Court. Most study participants were White (95% White, 4% Hispanic, 1% Asian or Pacific Islander, 1% African American). Of participants, 53% were female. Participants' average age was 43 years (SD = 14.98), and their average educational level was just below a bachelor's degree (highest grade completed, M = 15, SD = 2.65). Only 21% of

study participants actually served as jurors on the index case selected for study inclusion.

Of the 402 venirepersons called for selected cases and invited to take part in the study, 33% completed and returned the study measures. Notably, venirepersons were much more likely to participate when invited by telephone (51% participated) than by postcard (6% participated). Study participants did not differ from nonparticipants with respect to gender, X2(1, N = 229) = 0.84, p = .41; age, t(210) = -0.68, p = .50, or selection as jurors, X2(1, N = 232) = 2.36, p = .14. Relative to conservative census estimates of nonparticipants' characteristics (see above), study participants attained higher levels of education, X2(4, N = 160) = 21.69, p < .001, but did not differ in race and ethnicity, X2(4, N = 162) = 9.02, p < .10.

Measures

Insanity Defense Attitude-Revised

As explained later, the IDA-R consisted of 19 core and 3 supplemental items, the characteristics of which are detailed below.


Insanity Defense Support Scale

To test the convergent validity of the IDA-R, participants completed the IDS

(Hans, 1986), which was described earlier. In this study, the IDS formed three or-

thogonal components, including "punishment" (e.g., Even if people are insane, we should punish them if they break the law), "perceived danger" (e.g., The insanity defense allows dangerous people out on the streets), and "belief in justice and psychiatric treatment" (e.g., psychiatrists should testify about a defendant's mental condition in insanity trials). Because these components were quite consistent with the four factors originally identified by Hans (1986), component scores on these dimensions were used in the analyses reported below.

Attitudes Toward the Mentally Ill (AMI)

Participants' AMI were measured to assess their relationship to provide a measure of divergent validity for the IDA-R. To do so, items were selected from the

Community Attitudes Toward Mental Illness Scale (CAMI, Taylor, & Dear, 1981) to form the AMI scal. The original CAMI is a 40-item measure with good psychometric characteristics that appears to assess four dimensions (see Brockington, Hall, Levings, & Murphy, 1993; Taylor & Dear, 1981; Wolff, Pathare, Craig & Leff, 1996).

To avoid subject fatigue, eight items were selected from the CAMI to form the AMI. These items were chosen based on consideration of (a) the magnitude of their loadings on factors deemed important across studies (Brockington et al., 1993; Taylor & Dear, 1981; Wolff et al., 1996), and (b) a desire to minimize redundancy and response biases. PrC analyses of the AMI revealed three orthogonal factors that were similar to those identified in past research with the CAMI, including (a) "Community Mental Health Ideology" (CMHI), or acceptance of community- based psychiatric care (e.g., Residents have nothing to fear from people coming into their neighborhood to obtain mental health services; I would not want to live next to someone who is mentally ill), (b) "Locus of Responsibility for Mental Illness" (LR), reflecting beliefs that the mentally ill have control over their illness or deserve care

(One of the main causes of mental illness is lack of self-discipline and willpower; We have a responsibility to provide the best possible care for the mentally ill), and

(c) "Social Restrictiveness" (SR) reflecting beliefs that the rights of the mentally ill should be curbed to protect society (As soon as a person shows signs of mental disturbance, he should be hospitalized; Anyone with a history of mental illness should be excluded from public office). Component scores on these three AMI dimensions were used in analyses.

Revised Legal Attitudes Questionnaire-23

Legal authoritarianism, or an orientation toward defendants and the legal system that emphasizes control over due process, was measured using (see also Cutler et al., 1992; Kravitz, Cutler, and Brock's 1993) Revised Legal Attitudes Questionnaire-23 (RLAQ-23). Legal authoritarianism was included as a divergent measure for the IDA-R because it likely is related to IDAs, and is one of the most


effective predictors of mock jurors' decisions in criminal cases (e.g., Narby, Cutler, & Moran, 1993). The RLAQ-23 is a 23-item measure with good internal consistency, reasonably good convergent and divergent validity, but an unclear factor structure

(Kravitz et al., 1993). The RLAQ-23 also predicts the scores of individuals with known attitudes (e.g., political party affiliations). In keeping with the derivation study, we found no interpretable factor solution when we conducted PrC analyses of the RLAQ-23. Thus, the simple total sum score was used in analyses (see Kravitz et al., 1993).

Insanity Case Vignette and Construal Items

Participants were given a brief insanity case vignette based on that of Roberts et al. (1987) to permit tests of the predictive validity of the IDA-R. They were asked to act as a juror for the case. Specifically, they were asked to read the vignette, indicate the likelihood (0-100%) that they would deem the defendant insane, render a categorical verdict (Guilty or Insane) based on their own conceptions of insanity, and rate a set of case construal items. The case construal items asked about participants' perceptions of the defendant with respect to nine dimensions (i.e., the extent to which the defendant was mentally disordered; appreciated that his actions were wrong; was capable of perceiving alternatives, reasoning logically, act-

ing differently, behaving rationally; could help believing as he did; and should be blamed or punished). For instance, participants were asked, "To what extent do you think that the defendant appreciated that what he was doing was wrong before he acted?." A PrC analysis of the case construal items indicated a single factor solution

(Skeem & Golding, 2001). Scores on this case judgment component were used in

analyses.

Procedure

Selected venirepersons were approached and followed via the same procedures described in Study 1. When participants were mailed the study materials, the order of the measures was counterbalanced. Participants were paid $10 for their

participation.


Psychometric Characteristics of the IDA-R

IDA-R Item Refinement

Prior to conducting the factor analyses, the IDA-R data were screened and 7 outlying variables were deleted to refine the instrument. These 7 variables were included in the set of 9 provisional items in the modified IDA. These items had been rewritten in an attempt to address limitations, apparently with little effect. Thus, the final IDA-R was comprised of 19 key variables (used in most analyses), and 3 general opinion items.


Internal Structure and Consistency

To assess the structure of the IDA-R, a PrC was performed based on the correlation matrix of the 19 core IDA-R items. Two factors were extracted from the IDA-R that accounted for 55% of its total variance. Although the components were moderately correlated (r = .42), an orthogonal rotation (varimax) was applied because independent component scores were needed for further analyses and the

pattern of variable loadings produced by the oblique and orthogonal rotations was

virtually indistinguishable (factor score correlations between the two solutions were

>.97). Based on its interpretability and consistency with Thurstone's criteria for sim-

ple structure, this rotation appeared adequate. The rotated component solution appears in Table 1. To facilitate interpreta-

tion, variables in the pattern matrix are ordered and grouped by loading size, and

loadings under .15 are deleted (Tabachnik & Fidell, 1996). The 33 items are num- bered as in the original scale, with the exception of those of the third component. The component structure was highly consistent with that identified in Study One, with the first ("strict liability") and second component ("injustice and danger") cor-

responding directly to the first and second components, respectively, identified in

Study One. The internal consistency of these scales was fair (strict liability, a = .68) and good (injustice and danger, a = .88), particularly given that these were short

(9-item) scales. In summary, the two-factor structure of the IDA-R revealed in this

study appeared similar to that identified for the IDA in Study One. However, practical (different numbers of IDA/IDA-R items) and sample size limitations prohibited analyses that could formally test this issue.

Convergent and Divergent Validity

Although approaches that rely upon structural equation modeling are available to test a measure's convergent and divergent validity, our measures (which reflect a single method) and sample size (N = 135) are inappropriate for such approaches. We are aware that MTMM approaches that rely upon SEM are available. Our measures (shared method) and sample size (N = 135), however, are not well-suited for such approaches. Thus, we computed the IDA-R's association with the theoreti-

cally relevant measures in this study, and tested the significance of differences between its association with the convergent and discriminant measures. Intercorrela- tions among IDA-R component scores and the scales of the convergent (IDS) and

divergent (AMI; RLAQ-23) measures of validity are presented in Table 2. The data in this table indicate that, as predicted, the IDA-R correlates more highly with the

convergent measure than with the divergent measures (significance tests of these differences are presented below).

Because the IDA-R was developed partially based on consideration of existing measures, it contains three items (8% of the total IDA-R and IDS items) that are

highly similar to that of the IDS. However, analyses that excluded these three items did not change the results, indicating that these items did not unduly inflate the association between the IDA-R and IDS. Moreover, the IDA-R and IDS have different factor structures, indicating that they tap somewhat different domains. As shown in Table 3, the closest associations between the IDA-R and IDS involve their primary


Table 1. Study 2: Internal Structure of the IDA-R

Component Strict liability Injustice and danger

20. We should punish people who commit criminal .84 acts, regardless of their degree of mental disturbance.

21. It is wrong to punish people who commit crime -.78 for crazy reasons while gripped by uncontrollable...

11. A defendant's degree of insanity is irrelevant: if .76 .35 he commits a crime, then he should do the time.

1. I believe that people should be held responsible .75 .29 for their actions no matter what their mental condition.

13. Mentally ill defendants have failed to exert .72 .31 enough willpower to behave properly like the rest of us. So [punish].

25. Some defendants... are out of touch with reality -.72 and... cannot justly be blamed nor punished.

5. We should punish a person for a criminal act -.61 only if she understood the act as evil and then freely chose...

28. It is wrong to punish for an act they commit -.61 because of an uncontrollable illness... whether... epilepsy or mental illness.

10. I believe that severe mental illness can impair -.58 -.24 people's ability to make logical choices and control...

6. I believe that all human beings know what they .54 .38 are doing and have the power to control themselves.

27. With a sad story and slick attorneys, and .87 criminal can use the insanity defense to finagle his way to freedom.

17. The insanity plea is a loophole in the law that .39 .78 allows too many guilty people to escape punishment.

16. Perfectly sane killers can get away with their .78 crimes by hiring high-priced lawyers and experts who misuse...

8. The insanity defense threatens public safety by .32 .72 telling criminals that they can get away with a crime [with a story].

26. Many of the crazy criminals that psychiatrists .69 see fit to return to the streets go on and kill again.

22. Most defendants who use the insanity defense -.23 -.63 are truly mentally ill, not fakers.

4. If they are paid enough, psychiatrists will .61 manufacture a "mental illness" for any criminal...

12. The insanity defense returns disturbed, .33 .58 dangerous people to the streets.

14. As a last resort, defense attorneys will .21 .55 encourage their clients to act strangely and lie through their teeth...

Variance accounted for 26% 25%


Table 2. Study 2: Convergent and Divergent Validity of the IDA-R

IDA-R

Strict liability Injustice and danger

IDS: Punishment (reverse keyed) -.75** -.06 IDS2: Perceived dangerousness .10 .67** IDS3-Belief in justice and psychiatric treatment -.10 -.37** AMI1: Community mental health ideology (pro-care) -.26** -.12 AMI2: Locus of responsibility for -.31** -.03

mental illness (societal) AMI3: SR .12 .24** RLAQ-23: Legal authoritarianism .24** .39**

*p < .01. **p < .001.

scales. Specifically, the IDA-R "strict liability" scale is strongly (r = -.75) associated with the IDS "punishment" scale. Although both scales address opinions on the relevance of mental illness to punishment, the IDA-R scale also addresses the logic underlying these opinions. Moreover, the IDA-R "injustice and danger" scale is strongly associated (r = .67) with the IDS "perceived danger" scale. Although both scales address perceived abuse of the insanity defense and its threat to public safety, the IDA-R addresses these issues with more specific content. However, the IDA-R "injustice and danger" scale is only moderately associated (r = -.37) with the IDS "Belief in Justice and Psychiatric Treatment" scale. Although the scales both emphasize experts' ethics and the "purchasability" of the insanity defense, the IDS scale also addresses the extent to which the insane are entitled to treatment.

The IDA-R was also associated with the divergent measures, but these associations were significantly weaker than those with the convergent measure (IDS), particularly for the strict liability scale. First, the IDA-R's "strict liability" component was significantly (at p < .01) more strongly associated with its parallel IDS "punishment" scale than with the IDS "perceived dangerousness" and "belief in psychiatric treatment" scales (T2 = -10.55 and -8.07, respectively), all three AMI scales (T2 = -7.11, -6.36, and -10.15 for AMI1, 2, and 3, respectively), and the

Table 3. Study 2: Relative Predictive Utility of the IDA-R and Other Case-Relevant Attitudes

Case construal component Insanity likelihood rating

IDA-R: Strict liability .49** -.47** IDA-R: Perceived injustice .26** -.19"

and danger IDS: Punishment -.40** .35** IDS: Perceived dangerousness .26** -.18* IDS: Belief in justice and psychiatric -.26** .19*

treatment RLAQ23: Legal authoritarianism .29** -.16 AMI: Community mental -.09 -.03

health ideology AMI: Locus of responsibility -.23** .34**

for mental illness AMI: SR .12 -.07

*p < .05. **p < .01.


RLAQ (T2 = -10.89; Williams, 1959). Second, the IDA-R's "perceived injustice and danger" component was significantly (at p < .01) more strongly associated with its parallel IDS "perceived dangerousness" scale than with the IDS "punishment" and "belief in psychiatric treatment" scales (T2 = 8.01 and 13.11, respectively), and two of the three AMI scales (T2 = 8.35, 7.55, and 5.07 for AMI 1, 2, and 3, respectively), but not the RLAQ (T2 = 4.02).

The basic bivariate associations depicted in Table 3 reveal additional meaning- ful relationships among the IDA-R scales and other case-relevant attitudes. First, the IDA-R "strict liability" scale correlated moderately (r = -.31) with the AMI's "Locus of Responsibility for Mental Illness scale, indicating that beliefs that mental illness is irrelevant to criminal responsibility are associated with opinions that the mentally ill are responsible for their illness. Second, the IDA-R "injustice and

danger" scale moderately correlated (r = .39) with the measure of legal authoritarianism, the RLAQ-23, indicating that opinions that the insanity defense is easily abused with dangerous consequences are associated with opinions that crime control is more important than due process.

Predictive Utility

To assess the predictive validity of the IDA-R, particularly in relation to other measures of case-relevant attitudes, correlations were computed between these measures and insanity case vignette case construal component and insanity likelihood ratings. These are reported in Table 3. As shown in this table, the IDA- R, particularly the "strict liability" scale, strongly predicted venirepersons' case

judgments.

Incremental Utility

Two aspects of the incremental utility of the IDA-R in predicting venirepersons' categorical verdicts (guilty or insane) were assessed. First, the ability of the IDA-R to predict verdicts after controlling for the effects of attitudinal covariates (legal authoritarianism; AMI) was tested. A sequential stepwise logis- tic regression analyses (forward stepping, based on likelihood ratio statistics) was conducted in which RLAQ-23, AMI, and then IDA-R component scores were entered in sequential blocks to predict verdicts. This analysis indicated that there was a good model fit based on the effects of legal authoritarianism and AMI alone, X2(2, N = 135) = 31.50, p < .001, and that the degree of fit increased with the addition of venirepersons' IDA-R component scores, X2(4, N = 135) = 41.14, p < .001. Comparison of the log-likelihood ratios for models with and without the IDA-R showed significant improvement in prediction of verdicts with the addition of IDA-R component scores, X2(1, N = 135) = 9.64, p < .01.

Second, the ability of the IDA-R to predict verdicts after controlling for a competing measure of IDAs, the IDS, was assessed. A second sequential stepwise logis- tic regression analysis was conducted in which IDS component scores were entered in a block before IDA-R component scores to predict verdicts. This was a stringent


test, given the relatively high degree of correlation between these measures. Nev- ertheless, this analysis indicated that the good model fit based on the effects of the IDS scores alone, X2(3, N = 135) = 35.68, p = .000, increased with the addition of IDA-R scores, X2(4, N = 135) = 43.18, p = .000. Comparison of the log-likelihood ratios for models with and without the IDA-R again showed significant improvement in prediction of verdicts with the addition of IDA-R component scores, X2(1, N = 135) = 7.49, p = .006.

Study 3: Measure Cross-Validation

In the first two studies, the IDA-R was iteratively developed, refined, and validated with independent venireperson samples drawn from a mountain west state

(Utah). The third study was designed to cross-validate the IDA-R with a venireperson sample drawn from a southwestern state (Nevada). In this study, the IDA-R was administered to this new venireperson sample along with several insanity case

vignettes to test the generalizability of its two-factor structure and utility in predicting case judgments.

METHOD

Participants

Participants were 113 former venirepersons called to serve on randomly selected criminal and civil cases of the Eighth Judicial District Court, which represents approximately 68% of Nevada's population (United States Census Bureau, 2000). Most participants were White (78.8%; 8% Black, 6.2% Hispanic, 3.5% Asian, 1.8% Pacific Islander, .9% Native American), and female (62.8%). Participants' average age was 45.9 (SD = 13.89) and the mean highest grade completed was 13.66 (SD =

2.4). Most were dismissed from jury service without hearing a case (83.2%). Of the 184 venirepersons who agreed to participate, 61.4% completed and

returned their study materials. Because the demographic characteristics of non-

participants were unknown, they were estimated based on census statistics for the

population of Clark County, Nevada over the age of eighteen (United States Census Bureau, 2000). Relative to these conservative estimates, participants were more

likely to be female (X2[1, N = 113] = 8.5, p < .01), more likely to be high school

graduates (X2[1, N = 113] = 18.0, p < .001), and older (X2[1, N = 113] = 27.0, p < .001) than nonparticipants. Participants' median age was 47 years, whereas that of Clark County residents was 34. However, participants did not differ from non-

participant estimates with respect to race and ethnicity (X2[1, N = 113] = 0.98, ns).

Measures

Insanity Defense Attitudes-Revised

The IDA-R scale was described earlier. The scale consists of 19 core items (the chief items used for analyses) and three general opinion items.


Insanity Case Vignette and Construal Items

To assess the predictive utility of the IDA-R across a relatively broader range of

cases, participants were provided with four insanity case vignettes that were adapted from that used in Study 2 (see Roberts et al., 1987). In these vignettes, the instruc-

tions, general scenario, and crime characteristics were held constant, whereas fea- tures of the defendant were altered to match three types of intuitive conceptions of

insanity identified by Skeem and Golding (2001). Specifically, Vignette #1 depicted a defendant with "severe mental disability" (e.g., mentally retarded; totally debil-

itated); Vignette #2 depicted a defendant who was "morally insane" (e.g., psycho- pathic, psychotic, and unpredictably violent), and Vignette #3 depicted a defendant with "mental state centered" characteristics (e.g., unable to understand the crimi-

nality of his offense). Vignette #4 blended characteristics from the first three to represent a "consensus" conception of insanity. All four vignettes are available from the authors.

As in Study 2, for each vignette, participants were asked to read the case, indicate the likelihood (0-100%) that they would deem the defendant insane based on their own conceptions of insanity, render a categorical verdict (guilty or insane), and rate case construal items. Items were added to the case construal items of Study 1 to target symptoms that were specific to each of the multiple vignettes used in this

study (e.g., "To what extent do you think the defendant has a conscience?"; "To what extent do you think the defendant's intellectual abilities are impaired?"). As in Study 2, the case construal items were reduced via a PrC to a single component for each vignette.

Procedure

Prospective participants were invited to participate in the study in court on their first day of court service. After they completed their jury orientation, research assistants announced the study to potential participants. When participants were excused from or completed jury duty, an RA approached them to invite them to

participate. Fliers were left at the courtroom to allow potential participants to participate if the RA had left the courthouse before they were excused from jury service (22 participants (19.4%) were recruited in this manner). Venirepersons who

agreed to participate were provided the study materials to complete at home and, if necessary, contacted by telephone 2 and 4 weeks later to remind them to return the study materials. As in prior studies, provisions were made to ensure that

participants' responses were kept anonymous. Those who had not returned the materials after 8 weeks were called to inform them they were being dropped from the study. Notably, the IDA-R always preceded the case vignettes in the protocol, and the case vignettes were counterbalanced to avoid order effects. An instruction sheet was included to inform participants of the order in which to complete the measures, and the measures themselves had their order (e.g., "Step 1," "Step 2") printed in large font at the top. Those who returned the materials were paid $10.00.



Internal Structure and Consistency

Confirmatory factor analysis (CFA) provides a means of formally testing the fit of the two-factor IDA-R structure identified in Study 2 to these new data. Although we performed a CFA, the results should be viewed with caution, given the limited

sample of venirepersons in Study 3 (n = 113). To explore whether the oblique two- factor structure obtained in Study 2 (see Table 2) fit the data in this new sample, we subjected the 19 IDA-R items to maximum likelihood CFA analysis in EQS (Bentler, 1995). Because various indices of goodness of fit address slightly different issues, we report an absolute fit index (X), a relative fit index (CFI), and a

noncentrality-based index (RMSEA) (see Skeem, Mulvey, & Grisso, 2003). The

X2([151, N = 113] = 316.9, p < .001), indicated inadequate absolute fit, and the CFI of .87 fell below the .90 threshold typically deemed necessary for adequate relative fit. However, the RMSEA of .09 suggested adequate model fit. Given that "good- fitting models produce consistent results on many different indices" (Ullman, 1996, p. 752), it is clear that the two-factor model provides an imperfect fit to these data. However, it remains for future research to determine whether this is a function of limited sample size or the internal structure of the IDA-R.

To represent the pattern of correlations among IDA-R items in this new dataset, we performed an exploratory PrC on the correlation matrix of the 19 core IDA-R variables (as in Study 2). Because multiple indices suggested a two factor solution, two factors were extracted that accounted for 55% of the IDA-R's total variance. Although the components were moderately correlated (r = .44), an or-

thogonal rotation (varimax) was applied because independent component scores were needed for further analyses and (as before) the pattern of variable loadings produced by the oblique and orthogonal rotations was virtually indistinguishable. Based on its interpretability, consistency with Thurstone's criteria for simple structure, and consistency with the solution obtained in Study 2, this rotation appeared adequate.

The rotated component solution appears in Table 4. Variables in this matrix were ordered and grouped by loading size, and loadings under .15 are deleted. Items are numbers as in Study 2, but the full text of each item is provided. As shown in Table 5, the component structure in this new sample was consistent with that identified in Study 2, with items loading on the first ("injustice and danger") and second

component ("strict liability") corresponding quite directly with those for parallel components in Study 2. Both IDA-R scales possessed good internal consistency (injustice and danger, a = .90; strict liability, a = .80). Considering the results of the CFA, PrC, and internal consistency analyses, we tentatively conclude that the IDA-R possesses a two-factor structure.

Predictive Utility

To assess the predictive utility of the IDA-R in this new sample, we computed the strength of association between participants' IDA-R total and component scores (strict liability; injustice and danger) and their case construal scores


Table 4. Study 3: Internal Structure of the IDA-R

Component

Injustice and danger Strict liability

27. With slick attorneys and a sad story, any criminal .82 .19 can use the insanity defense to finagle his way to freedom.

16. Perfectly sane killers can get away with their crimes .82 .17 by hiring high-priced lawyers and experts who misuse the insanity defense.

14. As a last resort, defense attorneys will encourage .80 their clients to act strangely and lie through their teeth to appear "insane."

17. The insanity plea is a loophole in the law that allows .79 .35 too many guilty people to escape punishment.

4. For the right price, psychiatrists will probably .72 manufacture a "mental illness" for any criminal to convince the jury that he is insane.

8. The insanity defense threatens public safety by .71 .39 telling criminals that they can get away with a crime if they come up with a good story about why they did it.

12. The insanity defense returns disturbed, dangerous .64 .44 people to the streets.

26. Many of the crazy criminals that psychiatrists see fit .52 .26 to return to the streets go on to kill again.

22. Most defendants who use the insanity defense are -.49 -.25 truly mentally ill, not fakers.

25. Some people with severe mental illness are out of -.79 touch with reality and do not understand that their acts are wrong. These people cannot be blamed and do not deserve to be punished.

20. We should punish people who commit criminal acts, .42 .77 regardless of their degree of mental disturbance.

1. I believe that people should be held responsible for .29 .74 their actions no matter what their mental condition.

11. A defendant's degree of insanity is irrelevant: if he .43 .71 commits the crime, then he should do the time.

5. I believe that we should punish a person for a -.69 criminal act only if he understood the act as evil and then freely chose to do it.

21. It is wrong to punish people who commit crime for -.69 crazy reasons while gripped by uncontrollable hallucinations or delusions.

13. Mentally ill defendants who plead insanity have .36 .69 failed to exert enough willpower to behave properly like the rest of us. So, they should be punished for their crimes like everyone else.

8. It is wrong to punish someone for an act they -.11 -.62 commit because of any uncontrollable illness, whether it be epilepsy or mental illness.

6. I believe that all human beings know what they are .30 .59 doing and have the power to control themselves.

10. I believe that mental illness can impair people's -.19 -.40 ability to make logical choices and control themselves.

Variance accounted for 27% 27%


Table 5. Study 3. Predictive Utility of the IDA-R

IDA-R component Case construal Insanity likelihood (& vignette) component rating

Strict liability Vignette 1 .48** -.45** Vignette 2 .40** -.50** Vignette 3 .47** -.48** Vignette 4 .49** -.60**

Injustice and danger Vignette 1 .28** -.23* Vignette 2 .39** -.29** Vignette 3 .36** -.27** Vignette 4 .28** -.25**

Total IDA-R score Vignette 1 .53** -.49** Vignette 2 .56** -.56** Vignette 3 .59** -.54** Vignette 4 .55** -.61**

**p < .01. *p < .05.

and scaled verdicts for each of the four case vignettes. As shown in Table 6, the IDA-R's "strict liability" scale as well as the total score were strongly predictive of venirepersons' case judgments, and its "injustice and danger" scale was moderately so. The strength of association between IDA-R scores and case judgments were highly similar across manipulations of the defendant's characteristics, suggesting that the moderate-strong relation between IDAs and case judgments is not limited to particular constellations of case facts. In fact, multiple tests of differences in the strength of association (Williams, 1959) across vignettes for IDA-R component and total scores (n = 36 comparisons) yielded no significant differences.

GENERAL DISCUSSION

This research was designed to develop a psychometrically sound measure that would aid in understanding key dimensions of IDAs and in predicting jurors' verdicts in relevant cases. In a series of three studies conducted with over 400 venirepersons, we developed, iteratively refined, and validated a brief measure, the IDA-R scale. The results of these studies may be organized into three points. First, two

key dimensions may underlie venirepersons' attitudes toward the insanity defense: views of the extent to which mental illness is relevant to criminal responsibility and punishment (strict liability) and the degree of perceived injustice and danger associated with use of the defense. Second, the IDA-R assesses these two dimensions with good internal consistency, relates to external variables in a theoretically coherent manner, and is moderately to strongly predictive of mock jurors' insanity case

judgments. In fact, even after controlling for the effects of a competing measure of IDAs and such attitudinal covariates as legal authoritarianism, the IDA-R significantly predicted jurors' case judgments. Third, the predictive utility of the IDA-R

generalizes across geographic jurisdictions and manipulation of case facts. These

findings have both theoretical and practical implications.


Three Key Findings

Understanding Insanity Defense Attitudes

This series of studies employed a bottom-up approach for identifying key dimensions of contemporary IDAs. Based on a review of existing research and popular press articles, a broad item pool was developed and then iteratively refined. The product of this process, the IDA-R, appears to be underpinned by two key dimensions that echo the consistencies identified across past scales (see above; Hans, 1986; Roberts & Golding, 1991). The first dimension is strict liability, or the extent to which venirepersons believe that (a) mental illness reduces one's capacity for rational decision-making and control, and (b) reduced capacity is relevant to the issue of criminal responsibility. The second dimension is injustice and danger, which reflects the extent to which venirepersons believe the insanity defense is misused, perhaps with the effect of jeopardizing public safety. Thus, IDAs reflect one's views of fundamental logic that underlies the insanity defense, and of the extent to which the insanity defense is dangerously abused. As noted by Hans (1986), these dimensions are loosely consistent with alternative goals of punishment. A strict liability orientation is consistent with the principle of retribution: those who break the law ought to be punished as "payback," regardless of their degree of insanity. Similarly, concerns that the defense is unjust and dangerous is consistent with utilitarian goals: dishonest and/or insane criminals must be kept off the streets to control crime.

This research sheds light on the underlying dimensions of pervasive, largely negative attitudes toward the insanity defense. Of course, dimensions other than strict liability and injustice and danger may underpin venirepersons' attitudes. De- spite the inclusive, bottom-up approach used in this series of studies, it is possible that a dimension was under-represented and not identified. In fact, it is possible that the IDA-R does not possess a two-factor structure: factor analytic results from Study 3 were mixed, at best. The IDA-R must be administered to a substantially larger jury sample to definitively test its factor structure. Nevertheless, this series of studies demonstrates that the two dimensions of the IDA-R appear in different venireperson samples, are internally consistent, are quite predictive of case judgments, and have different patterns of external correlates that make theoretical sense. For example, strict liability is moderately associated with opinions that the mentally ill are responsible for their illness, whereas injustice and danger is moderately correlated with legal authoritarianism (see Table 3).

Construct Validity and Predictive Utility of the IDA-R

The IDA-R is the first measure of IDAs that has been systematically developed and refined. This process was productive in the sense that the IDA-R is not only reliable, but also relates to external variables in a coherent pattern and is useful in predicting case judgments. First, the IDA-R correlates more strongly with measures of the same construct (IDAs) than with measures of similar, but different constructs (attitudes toward mental illness; legal authoritarianism), and appears unassociated with social desirability. This pattern of association provides some support for the construct validity of the IDA-R.


Second, the IDA-R possesses moderate to strong predictive utility for insanity case judgments and scaled verdicts. This finding was robust across two samples of venirepersons drawn from different states and across five cases vignettes in which vastly different defendants were depicted. Of the IDA-R factors, strict liability is relatively strongly associated with case judgments and injustice and danger is moderately so. Regardless of location or defendant characteristics, venirepersons oriented toward strict liability and punishment are relatively likely to vote guilty.

In fact, in this series of studies, the IDA-R was the single best predictor of venirepersons' construal of case evidence and their case judgments. The IDA-R added incremental utility in predicting venirepersons' case judgments to competing measures of AMI and legal authoritarianism, which has been identified as a strong predictor of verdicts (Narby et al., 1993). In fact, the IDA-R added incremental validity to another measure of IDAs (IDS) in predicting case judgments. Thus, an important strength of the IDA-R is its ability to predict case judgments in these insanity defense cases. Future research must assess the extent to which this remains true when more realistic case materials (e.g., videotape or trial re-enactment) are used rather than short case vignettes.

Generalizability of the IDA-R

The third key finding of this study was that the reliability, internal structure, and predictive utility of the IDA-R generalized from venirepersons in Utah to those in Nevada. This suggests that the utility of the IDA-R in capturing venirepersons' attitudes toward the insanity defense may not be limited to a single geographic area. This is an important finding, given that attitudes are experience- based knowledge structures that have the potential for substantial individual differences.

Future research is necessary, however, to determine whether there are limits to the generalizability of the IDA-R. This research should be conducted in both the same and new jurisdictions. The importance of studying the same jurisdictions is underscored by the fact that only 33-61% of the venirepersons invited to take part in these studies completed the studies. Although the characteristics of participants were often similar to those of nonparticipants, the two groups may differ in ways that were not measured.

Potential Limitations

Because jurors likely have a broader range of experiences and attitudes than college students, we wished to develop the IDA-R using actual venirepersons. The only court-approved method for doing so was to recruit venirepersons at the courtroom and ask them to complete the study materials and mail in their responses.

Given that venirepersons' completed these three studies at home and were not supervised by researchers, it is possible that some participants did not complete the measures "on their own" or in the clearly prescribed order. An examination of the data, however, provides little evidence that this feature compromised this


research. First, statistical analyses failed to reveal significant outliers, which helps to rule out completely random responding. Second, the measures used in this study manifested a theoretically coherent pattern of relationships both internally (item analysis) and with one another (convergent/discriminant validity), suggesting that participants completed the measures in a consistent manner. Third, an examination of the raw study materials provided little indication that participants revisited and revised their responses to previously answered items. On balance, we feel that the benefits of conducting these studies with venirepersons who are relatively likely to represent the diversity of jurors' IDAs justifies the use of a less-controlled environ- ment than the laboratory setting.

Implications

This research begins to quantify the potential effect of jurors' attitudinal bias in insanity defense cases. The results support the premise that jurors are not blank slates, but complex individuals who come to jury duty with their own set of personal experiences, knowledge, and biases that affect their legal decision-making (Finkel, 1995). More directly, the results are consistent with prior findings that jurors' attitudes toward the insanity defense are powerful predictors of verdicts, explaining more variance in verdicts than manipulation of case facts or provision of judicial instruction (see Bailis et al., 1995; Cutler et al., 1992; Ellsworth et al., 1984; Homant & Kennedy, 1987; Roberts & Golding, 1991; Roberts et al., 1987).

Clearly, it is crucial to effectively apply procedural safeguards to select jurors who can apply the law without undue bias in insanity defense cases. The results of this study have implications for addressing the barriers to effective voir dire noted earlier. First, rather than rely upon stereotypic rules of thumb for selecting jurors, attorneys may consider using the IDA-R to help identify and exclude venirepersons with strongly negative views of the insanity defense. The predictive success and brevity of the IDA-R make it a practical tool for the voir dire process. Second, because the insanity defense invokes powerful biases, judges should consider rou- tinely exploring and addressing jurors' relevant attitudes in cases where this defense may be raised.

This would require stepping back from the increasing practice of conducting "streamlined" voir dire examinations (Johnson & Haney, 1994) and refusing to in- quire about bias against the insanity defense or even allowing jurors who express biases to be impaneled (Perlin, 1994). Judges' discretion in determining the topics addressed in voir dire is narrowed only in cases that involve interracial violent crimes, capital punishment, or significant pretrial publicity, in which potential jurors' racial prejudice, attitudes toward the death penalty, or preconceptions about the defendant's guilt, respectively, must be addressed (see Johnson & Haney, 1994; Sklansky, 1996). Although insanity defense cases invoke equally powerful biases, judges are not required to conduct similar inquiries in these cases (112 A.L.R. 531, 1996; 28 A.L.R. Fed. 26 ?24a, 1996).

Provided the time to identify biased venirepersons in insanity defense cases and the tools to do so, legal professionals may better protect defendants' right to a fair trial by jurors who can entertain their legally recognized plea of insanity.


ACKNOWLEDGMENT

Work on this project was supported through a Dissertation Fellowship from the University of Utah, grants from the American Academy of Forensic Psychology and the American Psychology-Law Society, and a Center for Advanced Research award from the University of Nevada, Las Vegas.

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