Encyclopedia of Psychology and Law

Another class of external correlates of psychopathy

comprises psychophysiological and behavioral vari-

ables that exhibit reliable patterns in North American

samples. The few cross-cultural studies investigating

such variables offer inconsistent findings. Additionally,

studies of performance on laboratory tasks that assess

cognitive and emotional processing in North America

suggest that Whites and Blacks high on psychopathic

traits may process information differently.

Studies conducted in North America and abroad on

the association between psychopathy and major men-

tal illness and personality disorders indicate similar

patterns for comorbid psychiatric diagnoses and self-

report personality traits. However, research investigat-

ing White and Black U.S. offenders suggests that

members of these groups do not manifest the same

patterns of correlations between psychopathy and

self-report personality measures. Whereas the associ-

ation between psychopathy and self-reported negative

affect is similar for Blacks and Whites, associations

between impulsivity and psychoticism are less consis-

tent. The observed discrepancies suggest that mecha-

nisms underlying psychopathy may differ for Blacks

and Whites and may be influenced by genetic and

sociocultural factors that vary across ethnic groups.

Measurement Generalization

Across Ethnic Groups

In contemporary research, psychopathy most often is

operationalized vis-à-vis the PCL family of measures.

Traditional psychometric evaluations indicate adequate

reliability for the PCL–R among non-White adults as

well as for adolescents of various ethnicities assessed

with the youth version of the measure. To demonstrate

cross-cultural equivalence of the PCL–R, it is also nec-

essary to demonstrate that the factor structure of the

measure is the same across ethnic groups (i.e., that the

same items or symptoms cluster together). There is

clear evidence of a replicable factor structure(s) among

White and Black adult men in U.S. prisons; among

White, Black, and Latino boys in the United States; and

among European men (including men from Scotland

and several continental European countries).

Cross-cultural equivalence in the case of the

PCL–R also requires that the association between test

scores and the latent trait of psychopathy be invariant

across ethnic groups (metric invariance), which may

be examined using item response theory (IRT). IRT

confers several distinct advantages to investigations of

cross-cultural disparities: Representative samples are

not required, more detailed analysis of individual rat-

ings can be provided, and a determination can be made

regarding whether scores are measured on the same

scale with different ethnic groups. An often-cited anal-

ogy that involves the measurement of temperature

using Fahrenheit and Celsius degrees may help clarify

the last point: Although both scales measure the same

construct, comparisons are meaningless because they

differ in zero points and scale increments. In the case

of the PCL–R, metric variance across groups is prob-

lematic because different scores could express the

same level of the latent trait of psychopathy (or, con-

versely, the same PCL–R score obtained by two groups

would not represent the same underlying level of the

disorder). In general, research using IRT methods indi-

cates that the PCL–R may be used in an unbiased way

with Blacks. However, there does appear to be evi-

dence of metric invariance between North America

and Europe (both in the United Kingdom and conti-

nental countries). Compared with North Americans,

Europeans tend to obtain lower PCL–R total, factor,

and item scores for the same level of the underlying

trait of the disorder, thereby prompting some experts to

recommend adjusting the diagnostic threshold of a

total PCL–R score of 30 used in North America to 28

when used in Europe. The symptoms tapping the defi-

cient affective experience seem to be the most diag-

nostic of psychopathy and are thought to be more

stable across cultures compared with the interpersonal

and behavioral features of the disorder. However, at

extreme levels of psychopathy, the interpersonal symp-

toms may provide more diagnostic information (espe-

cially in the United Kingdom). Research indicates that

these cross-national differences in psychopathy reflect

genuine differences in the expression of the disorder,

rather than raters’ perceptions of the psychopathic

symptoms.

Differences in Levels of

Psychopathic Traits

Because the generalizability of the measurement of

PCL–R total scores across Blacks and Whites has

been demonstrated, it is appropriate to use this instru-

ment to investigate whether these groups differ in the

extent to which they display psychopathic characteris-

tics. Two large-scale meta-analyses have examined

this issue for adults and adolescents. When differ-

ences between PCL–R total scores of Black and

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