INTRODUCTION
An increasing number of studies have indicated that educational,
linguistic, and cultural factors may have a significant influence on
neuropsychological test performance (e.g., Heaton et
al., 1996; Manly et al., 1998a; Welsh et al., 1995). Some authors have argued that
such findings reflect differences in underlying cerebral development
and organization among cultural groups (Kennepohl,
1999; Wong et al., 2000). Some
research has also suggested that certain minorities, including African
Americans, may be at increased risk for a number of neurological
conditions, including dementia (Welsh et al.,
1995), stroke (Giles et al., 1995),
spinal cord injury (Devivo et al., 1992), and
TBI (Rosenthal et al., 1996).
Although some researchers have suggested that this gap may be
shrinking (e.g., Flynn, 1999; Vincent, 1991), it remains well established that
African Americans as a group typically obtain significantly lower
scores on most measures of general cognitive ability (e.g., Kaufman et al., 1988; Reynolds
et al., 1987). In their re-analysis of the standardization
sample of the WAIS–R, for example, Kaufman et al. (1988) found significant effects for ethnicity in
each of the age groups assessed. The largest Black–White
differences between groups were observed on the Block Design and
Vocabulary subtests, tasks that correlate best with Full Scale IQ.
There is also accumulating evidence that current neuropsychological
measures may be culturally biased. Several studies with medically
healthy individuals have indicated that minorities in the United States
are considered cognitively impaired at much higher rates than European
Americans, even if one controls other variables such as years of
education and socioeconomic status (e.g., Jacobs et
al., 1997; Loewenstein et al., 1993,
1995; Manly et al.,
1998a; Marcopoulos et al., 1997; Welsh et al., 1995). Johnson-Selfridge et al.
(1998) reported a significant relationship
between ethnicity and word fluency after covarying for income level,
education, and single-word reading (WRAT–R Reading), with
European Americans producing significantly more words (FAS and Animal
Names) than Hispanic Americans, who in turn scored better than African
Americans. Manly et al. (1998a) found that
when using a standard cut-off (more than 1 SD), at least 25%
of a relatively large medically healthy African American sample
(N = 170) scored in the impaired range on 12 of 16
neuropsychological measures administered. Sixty-five percent would have
been classified as impaired on a naming task (Boston Naming Test).
In light of the above findings, there has been increased demand for
the development of more appropriate normative data for use with African
Americans (Manly & Jacobs, 2000; Nabors et al., 2000). However, there remain several
unanswered questions, not the least of which concerns the origin of
these differences. Cultural explanations for such findings have been
increasing (e.g., Helms, 1992, 1997; Neisser et al.,
1996). Culture may be defined as “the customs, values,
traditions, and behavioural practices (including information-processing
strategies) that define a group” (Helms, 1997, p. 520). In its most general form, the
“cultural hypothesis” argues that limited exposure to
mainstream (in this case American) culture will deleteriously affect
performance on tests developed for use within the majority
ethnic/cultural group (Helms, 1997).
The concept of acculturation has emerged as an important and
practical concept in the study of cultural factors in pluralistic
societies, and occurs when two or more groups come into continuous
first-hand contact with each other for an extended period of time
(Berry, 1989). Level of acculturation has
been defined as the degree to which an individual espouses the cultural
values, beliefs, and practices of a given ethnic group versus
that of the dominant ethnic/cultural group (Landrine & Klonoff, 1995). Although such
research has traditionally been conducted with immigrants, the concept
of acculturation has more recently been applied to other minority
groups, including the development of specific acculturation scales
(e.g., African American Acculturation Scale; Landrine & Klonoff, 1994).
Few studies have formally assessed the degree to which level of
acculturation may affect neuropsychological test performance. Arnold et
al. (1994) assessed the relationship between
Mexican American acculturation (Cuellar et al.,
1980) and neuropsychological test performance. Their findings
revealed a significant effect of acculturation for the Category test,
Tactual Performance Test, and Seashore Rhythm Test after controlling
for age, sex, and educational level. These authors speculated that
these differences might reflect variations in problem solving and
bilingualism among the cultural groups.
Manly et al. (1998a) conducted two studies
assessing the impact of African American acculturation on
neuropsychological test performance. In a first study, neurologically
normal African American participants were asked to complete a battery
of neuropsychological tests as well as an acculturation measure
(African American Acculturation Scale–Short Form; Landrine & Klonoff, 1995). Level of
acculturation predicted a significant amount of variance on many of the
tests (Category Test, Trails A and B, WAIS–R Information, Block
Design, and Digit Symbol, Boston Naming Test, the learning components
of the Figure and Story Memory Tests, and Grooved Pegs). After
controlling for the influence of demographic factors (age, sex, and
years of education), acculturation effects remained significant for
WAIS–R Information and the Boston Naming Test. In a second study,
HIV-positive African American and European American participants were
matched for age, education, sex, and HIV disease stage. Black
participants scored significantly lower on the Category Test,
WAIS–R Vocabulary, Boston Naming Test, WAIS–R Block Design,
Grooved Pegboard (non-dominant), and the learning components of verbal
(Story Learning) and visual (Figure Learning) memory tests. Covariance
for acculturation scores resulted in all but one of these scores (Story
Learning) becoming non-significant.
Some have proposed that mistrust of institutions among some African
Americans may be another factor explaining certain ethnic/cultural
differences. Terrell et al. (1981) directly
assessed the role of mistrust on cognitive test performance. One
hundred Black college students were administered a questionnaire
(Cultural Mistrust Inventory) to assess their tendency to mistrust
Whites. Participants were then divided into two groups (high
vs. low mistrust) on the basis of their scores on this scale.
Half the sample was administered the WAIS by a White examiner, the
other half by a Black examiner. Although no main effects of examiner
ethnicity or mistrust were evident, two significant interactions were
found. Of those scoring high on the mistrust measure, those assessed by
a Black examiner performed significantly better than those assessed by
a White examiner (Black examiner–high mistrust > White
examiner–high mistrust). If examined by a White examiner, those
with lower mistrust performed better (White examiner–low mistrust
> White examiner–high mistrust). Taken together, these
findings suggest that underlying attitudes of mistrust in some Black
test-takers might moderate cognitive test performance under specific
circumstances. Furthermore, Steele (1997) has
suggested that the underlying threat of negative stereotyping may also
affect performance on cognitive tests among African Americans. In an
intriguing set of studies, African American and European American
university students were given a subset of items from the Graduate
Record Examination (GRE). Half were told that it was a measure of
“intellectual” ability; the remaining were told it was an
assessment of “problem solving” ability. African Americans
told that the measure was an indicator of general intelligence obtained
lower scores than their matched European American counterparts; no such
differences were found in the groups told the test was assessing a
general ability to solve problems. In a follow-up study, simply asking
participants to identify their racial background seemed to negatively
affect the scores of African American participants on a problem-solving
task. African Americans who were not asked their ethnic background
performed just as well as the European American groups (Steele, 1997).
The goal of the present study was to specifically assess the
influence of acculturation on neuropsychological test performance in a
sample of individuals who had sustained a traumatic brain injury (TBI).
There are a number of reasons why such a study seemed important,
particularly in the case of TBI. First, this study represents one of
very few to directly assess the influence of cultural factors on
neuropsychological testing, and would potentially provide direct
support for the cultural hypothesis of group differences on
cognitive/neuropsychological tests. Second, some authors have
suggested that minorities (including African Americans) are
disproportionately represented in TBI populations, thereby increasing
the relevance of such issues in TBI-related research (Rosenthal et al., 1996). If African American
acculturation were found to be a significant predictor of
neuropsychological test performance, this would likely increase the
risk of misdiagnosing a significant proportion of individuals with TBI.
Third, it seemed important to replicate the findings regarding level of
acculturation and neuropsychological test performance within a TBI
population, particularly as some of the prior literature could
potentially be considered contradictory. On the one hand, there seems
to be preliminary evidence that the influence of cultural factors on
neuropsychological test scores may actually become more prominent with
increased neurological impairment (e.g., Loewenstein
et al., 1993). However, these findings should be contrasted with
other reports suggesting that the use of demographic adjustments or
corrections (of any kind) following TBI may not be necessary in the
assessment of clear cases of neuropathology (e.g., Reitan & Wolfson, 1995).
It was generally hypothesized that individuals who espouse more
traditional African American cultural values and beliefs (i.e.,
lower level of acculturation) would obtain lower scores on
many of the administered tests. Cultural factors were also expected to
predict test performance above and beyond what might be anticipated
from other demographic factors such as age, sex, education, and
socioeconomic status (SES). On the basis of prior findings, it was also
hypothesized that acculturation effects would more likely be found on
tests assessing language-related skills and/or complex cognitive
abilities such as problem solving and reasoning. Finally, we expected
that examiner ethnicity might affect test performance among
participants that report some degree of cultural mistrust of majority
White culture.
METHODS
Research Participants
All participants in the current study were already involved in the
South Eastern Michigan Traumatic Brain Injury Systems (SEMTBIS) project
at the time of their recruitment. The SEMTBIS project is part of a
large, multicenter research effort dedicated to the collection of data
on brain-injured individuals (Dahmer et al.,
1993) and is funded by the National Institute on Disability and
Rehabilitation Research. As part of the SEMTBIS project, participants
complete a battery of neuropsychological tests, questionnaires, and
rating scales at regular intervals post-TBI. Participants were
recruited for the current study at approximately 1, 2, 5, or 10 years
post injury. Following their completion of the SEMTBIS measures,
participants were asked to complete a brief 5 to 10 min questionnaire.
Participants typically filled out the questionnaire in written form;
however, in cases where this proved too difficult (e.g., because of
reading difficulties), participants were read items aloud. All
participants were self-identified as “African American”
from a set of written choices. Other variables of interest were
obtained from the SEMTBIS database.
A total of 71 individuals between the ages of 21 to 76 years at the
time of their participation (M = 42.2 years, SD =
13.1) were recruited over a 2-year period (1999–2001). As with
most studies involving TBI, the proportion of males was greater (81.7%
of the sample, n = 58). Mean years of education was about that
of a high school graduate (M = 11.8, SD = 2.0).
Approximately 45% of the sample was employed at least part-time
(n = 32) prior to injury. As might be expected, there was a
considerable drop-off in employment when comparing pre- and post-injury
data. Of the 32 participants working at the time of their accident,
only 9 were employed at the time of their post-injury assessment. The
Hollingshead Two Factor Index of Social Status (Hollingshead, 1957, cf. Hollingshead,
1975) was used to derive a numerical estimate of SES. Premorbid
occupational status was used in the derivation of SES. Using this
measure, more than half of the sample (n = 31) was in the
lowest SES bracket, and the vast majority (n = 42) were in the
lowest two social strata (“Lower” and “Lower
Middle”).
Injury Characteristics
Almost half of the current sample (n = 33) incurred their
TBI as a result of an assault. Of these, ten were the result of a
gunshot wound. The other major cause of injury involved some type of
motor vehicle accident (41%), either as occupants of a motor vehicle
(n=20) or as pedestrians (n= 9).
Other causes included falls (n = 9) and a cycling accident
(n = 1). Time since injury was relatively evenly distributed.
A little more than half were evaluated at 1 (n = 23) or 2
years (n = 15) following their TBI. Fifteen were assessed at 5
years post injury, and 18 at 10 years post injury. Lowest Glasgow Coma
Scale (GCS) score within the first 24 hr of hospital admission was used
as the indicator of injury severity (Teasdale &
Jennett, 1974). Within the current sample, 33 individuals
(46.5%) incurred a severe TBI (GCS = 3–8), 15 (21.1%) had a
moderate injury (GCS = 9–12), while 23 participants (32.4%) were
considered to have sustained a mild TBI (GCS = 13–15). It should
be noted that mild TBI cases consisted of more complicated injuries
that required inpatient rehabilitation. A number of the participants
reported having suffered some form of head injury or concussion prior
to their TBI (n = 7).
Measures
Individual neuropsychological tests
The complete test battery, as well as the number of individuals
completing each of the tests, is provided in Table
1. Some participants could not complete the entire battery,
often because of residual physical limitations (e.g., inability to
complete paper-and-pencil tasks). A total of 20 test scores were
obtained from the above list of measures. Raw test scores were used in
all analyses.
List of tests in the South East Michigan Traumatic Brain Injury
Systems Study (SEMTBIS) Neuropsychological test battery
Composite measure of neuropsychological test
performance
A composite measure of overall neuropsychological test performance,
the “Overall Test Battery Mean” (OTBM), was calculated
using all but one of the above listed neuropsychological measures
(i.e., excluding the Galveston Orientation and Amnesia Test). The OTBM
is derived by converting all obtained scores to a common metric
(T-scores) and subsequently calculating the mean of the obtained
T-scores (see Miller & Rohling, 2002).
Unfortunately, available norms often employ different methods for the
correction of demographic factors. Calculated OTBM scores thus
represent an attempt at a “best corrected” estimate based
on available norms. Norms used in the derivation of the individual OTBM
scores are provided in the Appendix. An OTBM score was obtained for
most of the participants (n = 69), and a composite measure was
not calculated if participants had fewer than 14 test scores.
Level of acculturation
Each participant's level of acculturation was assessed using the
African American Acculturation Scale–Short Form (AAAS–33;
Landrine & Klonoff, 1995). The
AAAS–33 is a shortened version of the African American
Acculturation Scale (Landrine & Klonoff,
1994), a measure developed to assess the degree to which an
individual espouses the traditions, values, beliefs, assumptions, and
practices specific to traditional African American culture. According
to the developers, the short form is highly correlated with the
original version (r = .94). A Likert-type scale ranging from 1
(I totally disagree, this is not at all true of me) to 7
(I totally agree, this is absolutely true of me) is used to
rank attitudes/opinions in response to each of the 33 statements.
High scores represent a more traditional African American cultural
background (lower degree of acculturation); conversely, low scores
suggest greater acculturation to majority American society (higher
degree of acculturation).
The AAAS–33 is divided into 10 subscales assessing different
aspects of African American culture; namely (1) Preference for
African American Music, Arts, and People; (2) Religious
Beliefs/Practices; (3) Traditional Foods; (4)
Traditional Childhood Experiences; (5) Superstitions;
(6) Interracial Attitudes/Cultural Mistrust; (7)
Falling Out; (8) Traditional Games; (9) Family
Values; and (10) Family Practices. In the standardization
sample, total scores on the AAAS–33 were found to be relatively
independent of income, social status of the family of origin, and
educational level (Landrine & Klonoff,
1995). Concurrent validity was demonstrated by establishing that
the scale could differentiate between African American and non-African
American respondents. Moreover, the scale distinguished between those
African Americans who lived in predominantly Black neighborhoods from
those living in mostly integrated ones. A set of subscores of the
AAAS–33 was used in another study assessing African American
acculturation and neuropsychological test performance (Manly et al., 1998a).
Examiner Ethnicity
As the SEMTBIS is a large project, participants were recruited and
assessed by research assistants of different ethnic backgrounds. More
than half (n = 40) of the test protocols were administered by
a Black examiner; the remainder (n = 31) by a White
examiner.
Statistical Methods
Relationship of acculturation to neuropsychological
test performance
The purpose of the study was essentially twofold: (1) to establish
level of acculturation as a valid predictor of neuropsychological test
performance, and (2) to assess the influence of acculturation after
controlling for other demographic variables. Two sets of analyses were
thus performed on each of the 20 neuropsychological test scores. First,
hierarchical multiple regression/correlational (MRC) analyses were
used to assess the effect of acculturation on neuropsychological test
performance. Factors related to the injury (i.e., lowest GCS in the
first 24 hr and time since injury) were included as an initial
covariate set, followed by level of acculturation. Second, follow-up
hierarchical MRC analyses were conducted using demographic factors as a
second covariate set (i.e., after the injury-related factors and before
the acculturation factor). A hierarchical MRC analysis was also used to
assess the relationship between acculturation and the composite measure
of overall neuropsychological test performance (OTBM). Unlike other
neuropsychological measures, the OTBM already accounts for demographic
factors through its use of corrected T-scores. Hierarchical MRC
analysis was conducted using injury-related factors as an initial
covariate set.
RESULTS
Data Screening
Descriptive statistics are provided in Table
2. Prior to analyses, all demographic, acculturation, and
neuropsychological variables were screened for univariate outliers and
normality. Although some of the observed distributions were judged to
be non-normal (i.e., some degree of skewness), raw scores were retained
in light of the chosen statistic's (MRC) relative robustness to
violations of normality. None of the inter-correlations between
independent variables exceeded 0.7, a suggested upper limit with
regards to multicollinearity in regression analyses (Tabachnick & Fidell, 1989). Unless otherwise
specified, an alpha level of .05 was used for all statistical tests.
Descriptive statistics for injury-related, demographic and
acculturation variables for the entire sample
Relationship Between Demographic and Injury-Related
Variables
Consistent with prior studies with TBI (e.g., Kraus & McArthur, 1999), a one-way ANOVA
revealed a significant relationship between age and cause of injury
[F(4,66) = 9.37, p < .001].
Post-hoc analyses using the studentized Newman-Keuls test
suggested that older individuals were more likely to be injured as a
result of a fall or as pedestrians, whereas younger participants were
more likely to be injured as a result of a motor vehicle accident
(p < .05). There was no significant relationship between
injury-related variables (i.e., injury severity or mechanism of injury)
and demographic variables (i.e., sex, years of education, SES) or level
of acculturation.
Relationship Between Demographic Variables and Level
of Acculturation
There was no significant correlation between AAAS–33 Total
Score and demographic variables (age, sex, years of education, or SES).
Furthermore, there was no significant relationship between any of the
AAAS–33 subscales and age, years of education or SES. However,
males reported having played significantly more traditional games
[t(69) = −2. 351, p < .05], and
females reported eating/preparing more traditional foods
[t(69) = 2.037, p < .05].
Effect of Examiner Ethnicity
We first assessed the relationship between examiner ethnicity and
acculturation measures using multiple independent sample t
tests. There were no significant differences according to examiner
ethnicity on the AAAS–33 or any of its subtests. We divided
participants into groups according to their degree of mistrust on the
basis of an individual's score (i.e., above or below the median)
on the Cultural Mistrust subscale of the AAAS–33. Subsequent 2
× 2 ANOVAs were conducted for each of the neuropsychological test
scores, as well as for the OTBM. Our results revealed a significant
main effect of examiner ethnicity for Block Design
[F(1,64) = 6.98, p < .05] and Trails A
[F(1,65) = 4.09, p < .05]. In each case,
participants performed better when administered by a Black examiner.
There were no significant main effects for cultural mistrust. There
was, however, a significant examiner Ethnicity × Cultural
Mistrust interaction for both Trails A [F(1,65) = 5.54,
p < .05] and Trails B [F(1,59) = 4.06,
p < .05]. Post-hoc analyses using the
Newman-Keuls test (p < .05) revealed that these
interactions were largely due to poorer performance on the Trail Making
test by participants who were assessed by a White examiner and
who reported a greater distrust towards Whites (high mistrust). There
were no significant effects of examiner ethnicity or cultural mistrust
relative to overall test performance (OTBM).
Relationship of Acculturation to Neuropsychological
Test Performance
Individual neuropsychological tests
In the first set of regression analyses, decreased level of
acculturation was significantly associated with poorer performance on
the GOAT, MAE Tokens, WAIS–R Block Design, RAVLT Total Trials
1–5, RAVLT delayed recall, and written SDMT after controlling for
injury-related variables (lowest GCS, time since injury). Level of
acculturation remained a significant predictor of scores on all of the
above tests except for RAVLT delayed recall after controlling for
injury-related and demographic factors. A summary of the proportions of
variance accounted for by acculturation in each of the MRC analyses is
provided in Table 3. It is worth noting that
all significant findings occurred in the a priori predicted
direction, with lower acculturation associated with decreased test
performance.
Proportion of variance in neuropsychological test performance
accounted for by level of acculturation
Composite neuropsychological measure (OTBM)
A lower degree of acculturation was associated with lower scores on a
composite measure of overall neuropsychological test performance
(OTBM). Results of the hierarchical MRC analysis are presented in Table 4. While covarying for injury-related
variables, level of acculturation was significantly associated with the
OTBM (β = −.351, p < .01), uniquely accounting
for 11.9% of the total variance. Initial GCS score was also a
significant predictor of OTBM (β = .262, p < .05).
Although the proportion of variance associated with level of
acculturation appeared greater than that accounted for by
injury-related factors (11.9% vs. 4.7% of the total variance),
there was no significant difference (using Fisher's transformation
r to r′) in terms of their relative predictive
ability.
Summary of hierarchical regression analysis for variables predicting
the Overall Test Battery Mean (OTBM) (N = 69)
DISCUSSION
Overall, our findings suggest a significant association between level
of African American acculturation and neuropsychological test
performance, even after controlling for other potentially confounding
variables such as injury severity, time since injury, age, sex, years
of formal education, and socioeconomic status. Within the current
study, level of acculturation was a significant and unique predictor of
test performance across a wide variety of neuropsychological domains,
including attention/orientation, language,
visuomotor/processing speed, visuospatial/constructional
skills, and memory. These findings were all in the expected direction,
as more traditional African American cultural values/beliefs were
associated with lower test performance. Perhaps the most telling
evidence was the significant relationship between level of
acculturation and a composite score of overall neuropsychological test
performance (OTBM), even after covarying for injury severity and time
since injury.
These results appear to provide additional support for the cultural
hypothesis of group differences on cognitive/neuropsychological
tests. Helms (1997) has referred to the
difficulties in assessing the contributions of race, SES, and culture
in the interpretation of ethnic/cultural group differences on
cognitive tests. Within the current study, limiting the sample to
African Americans emphasized cultural differences within a
single ethnic/cultural group while avoiding other potential
confounding factors increasing between-group variability
(e.g., impact of minority status). In addition, the current sample was
relatively homogeneous in terms of socioeconomic status (i.e.,
predominantly lower to lower-middle SES), minimizing the variability
attributable to an individual's access to economic resources.
Residual differences in SES were also statistically controlled using a
well-established measure (Hollingshead Index).
It was initially hypothesized that an individual's score on
tasks assessing verbal ability would be more culture-dependent.
Accordingly, scores on a test assessing receptive language (Tokens
Test) demonstrated a significant and unique acculturation effect. This
finding seems consistent with previous findings linking African
American acculturation with language-related measures such as the
Boston Naming Test (Manly et al., 1998a). In
that same study, use of Black English was also associated with lower
scores on certain neuropsychological tasks, including some verbal
measures (i.e., WAIS–R Information). At this stage, however, it
remains unclear whether such findings represent a specific
language-related difference between cultural groups, or if the use of
Black English might serve as another indicator of a more general
acculturation factor.
The hypothesis that executive functioning measures would specifically
be associated with cultural factors was generally not borne out in this
study. However, acculturation level accounted for a significant amount
of variance on the Block Design subtest, a measure often considered to
be a test of nonverbal reasoning. In their investigation of
acculturation effects among HIV-positive individuals, Manly et al.
(1998a) reported significant
Black–White differences on Block Design and the Halstead Category
Test (another nonverbal measure of problem solving/reasoning).
These findings are interesting in the context of research involving
psychometric intelligence. Kaufman et al. (1988) reported that the greatest relative
Black–White differences were on the WAIS–R Block Design and
Vocabulary subtests. These subtests also consistently demonstrate the
highest correlations with overall psychometric intelligence (Full-Scale
IQ). In conjunction with other studies (Manly et
al., 1998a), these results suggest that ethnic/cultural
group differences in performance on these particular subtests (i.e.,
Vocabulary and Block Design) may be partly attributable to differences
in cultural experience. Unfortunately, prior studies reporting
ethnic/cultural differences on intelligence testing did not account
for level of acculturation in their analyses.
Our findings also suggest that level of acculturation may be
significantly and uniquely related to a measure of verbal learning (Rey
Auditory Verbal Learning Test). Other studies have reported ethnic
group differences on memory measures after controlling for various
demographic factors (e.g., Manly et al., 1998b, Marcopoulos et al.,
1997). Some prior research has suggested that some Blacks
categorize items differently than Whites when trying to remember
information (e.g., focusing on holistic aspects rather than details),
which may partly account for our current findings (Shade, 1991). Cultural differences in
language-related skills may also have mediated an individual's
encoding of the word list. Supporting this position is the observation
that although initial learning of the verbal list (total recall for
Trials 1–5) was significantly related to cultural experience,
this acculturation effect was not observed for the delayed recall trial
after correcting for other demographic factors. Previous research has
also indicated an association between Black English use and the
learning component of a verbal memory test (Manly et
al., 1998a).
We did not expect the significant relationship between level of
acculturation and performance on a measure of divided attention and
visuomotor speed (Symbol Digit Modalities Test). Although preliminary,
this finding is nevertheless consistent with other reports of
Black–White differences on speeded tasks (e.g., Miller et al., 1993), and serves as a reminder that
no task may be considered culture-free without empirical verification.
Potentially the most unexpected finding, however, was the significant
relationship between scores on a measure of basic
attention/orientation (Galveston Orientation and Amnesia Test) and
level of acculturation. Some authors have cited that traditional
African American culture adheres to a more socially defined time
perspective, contrasting with mainstream American “clock
time” (Nobles, 1972; Willis, 1989), and it could be that an
individual's relative time perspective might have affected the
overall score. It is interesting to note that this measure is often
used in the determination of post-traumatic amnesia (PTA) following
acute TBI (Levin et al., 1979). Although
these findings were obtained at least 1 year post injury (when most
effects of TBI on basic attention/orientation are considered to
have resolved), future research will be necessary to determine if level
of acculturation should be taken into account when using the GOAT in
more acute settings.
Prior studies assessing cross-cultural applicability of
neuropsychological tests have typically focused on the assessment of
the equivalence of specific tests across cultures (e.g., Maj et al.
1993). In contrast, our findings indicate
that cultural experience may influence a wide variety of
neuropsychological tests and domains, at least with African Americans.
Arguably, our findings might be reflective of a single more general
acculturation factor mediating performance on all or the majority of
the tests, albeit to varying degrees. If such findings are replicated,
this would imply that current difficulties in cross-cultural assessment
will not simply be resolved through the use of specific
“culturally-appropriate” tests. Rather, more in-depth
knowledge of each of the respective cultures would be necessary,
including an understanding of issues such as the cultural saliency of
the ability being assessed, familiarity with materials and task
demands, and overall level of comfort and motivation within the testing
environment.
Our findings also raise interesting questions regarding the current
conception and definition of cultural bias in neuropsychological
assessment. Cultural bias has sometimes been defined as the
“constant or systematic error, as opposed to chance or random
error, in the estimation of some value … this constant or
systematic error is alleged to be due to group membership or some other
nominal variable” (Reynolds, 2000, p.
250). Even if one assumes a unidimensional model of acculturation,
evaluating potential sources of bias solely in terms of a nominal
variable (e.g., Black vs. White) would appear misleading. Our
findings suggest that many variables potentially underlying such group
differences (including cultural factors) might be better understood as
continuous rather than nominal variables.
Some of our results suggest that the ethnicity of the examiner may
also have an effect on certain test scores when assessing African
Americans (i.e., Block Design, Trail Making Test). In keeping with
prior research (Terrell et al., 1981), this
effect seems to be largely moderated by the participant's
underlying mistrust of the majority cultural group. It is important to
note that these findings were limited to specific tests and were not
found when evaluating the majority of neuropsychological measures or
overall test performance. Such findings nevertheless suggest that in
situations involving cross-cultural testing, factors underlying
examiner/examinee relationships and their impact on performance are
likely to highly complex and deserving of more detailed study.
The current study has a number of notable limitations. It remains
possible that level of acculturation might be serving as a surrogate
for other underlying demographic variables. For example, gross
estimates of educational attainment do not fully account for the
quality of the educational experience. Qualitative differences in
education have already been suggested as a potential explanation for
Black–White differences on cognitive testing among high school
and college students (Myerson et al., 1998).
Recent studies have also reported that other indices of academic
achievement (e.g., single-word reading level) may partially account for
ethnic group differences in neuropsychological test performance (Manly et al., 2000).
It remains difficult to evaluate the possible influence of stereotype
threat on test performance within the current study. It should be noted
that all participants were intentionally and specifically approached
after completing the testing in order to minimize the
influence of any such underlying anxiety regarding performance.
Moreover, it could be argued that any decrease in scores would more
likely be interpreted as a direct consequence of their head injury and
not as a result of being a member of a particular ethnic group.
However, it certainly remains possible that pre-existing negative
stereotypes (i.e., that African Americans do poorly on standardized
tests) could have affected the performance of some of the
participants.
Similarly, level of acculturation might also be confounded with the
more general concept of acculturative stress, defined as the
universal difficulty faced by members of minority groups when adapting
to the larger society (Berry, 1989). There
may well be an identifiable cost in maintaining more traditional
cultural values/beliefs, perhaps in the form of increased
discrimination (Landrine & Klonoff,
1996). Given the potential relationship between affect and
neuropsychological test performance (e.g., Bowman,
1996; Veiel, 1997), our findings might
reflect the tendency for individuals with increased acculturative
stress to obtain lower test scores. According to Berry (1989), however, individuals most vulnerable to
acculturative stress are expected to be those who reject both
minority and majority cultures. We would not expect an individual that
rejects both cultures to demonstrate a high score on a scale such as
the African American Acculturation Scale (suggesting a lower level of
acculturation). One could also readily envision a relationship between
the concepts of stereotype threat and acculturation, potentially in the
form of acculturative stress. A potentially interesting area of future
research would be the investigation of the relationship between level
of acculturation, stereotype threat and even examiner ethnicity on
testing among ethnic/cultural minorities.
The use of a brief unidimensional acculturation measure, although
practical, has a number of shortcomings. Measures such as the
AAAS–33 can only be considered an indirect measure of the complex
factors that make up a culture (Betancourt &
Lopez, 1993). As Landrine and Klonoff (1996) point out, although scores in the more
extreme ranges may more readily be characterized as representative of
either more traditional or acculturated individuals, the precise
meaning of scores in the scale's midrange is less clear. Current
acculturation measures do not wholly describe the cultural experience
of those “bicultural” individuals who share
values/beliefs from both cultures. Other aspects of African
American culture that might also affect neuropsychological findings
(e.g., Black English) were not assessed. Future studies, preferably
designed and conducted by researchers familiar with the culture in
question, may eventually clarify the nature of the processes underlying
such differences.
As a final limitation, it should be pointed out that the above
findings are the result of a large number of analyses and should be
considered exploratory rather than confirmatory in nature. These
results require replication, particularly with regards to the
relationship between level of acculturation and specific
neuropsychological tests. Although the use of a relatively homogeneous
sample (i.e., primarily males of limited education/lower SES with a
TBI from a single geographic location) does allow for a more controlled
study, it also limits the generalizability of the current findings. It
remains unclear to what extent acculturation might affect
neuropsychological testing among African Americans of higher
socioeconomic status, of different geographic regions, or with other
types of neuropathology.
In conclusion, the findings of this study provide evidence for the
importance of cultural factors in the neuropsychological assessment of
African Americans following a traumatic brain injury. More generally,
the clinician conducting an assessment with an African American client
should be aware of the many variables of potential importance (e.g.,
level of acculturation, years/quality of education, SES, perceived
discrimination) in order to conduct a more culturally sensitive
neuropsychological evaluation (see also Nabors et
al., 2000). On the basis of such findings, the use of
acculturation scales in the neuropsychological assessment of African
Americans would certainly seem advisable. However, it is important to
emphasize, given the complexity of the issues involved, that inclusion
of an acculturation scale cannot be considered an adequate
“correction” for the influence of cultural factors within
the context of a clinical neuropsychological assessment. Further
research in this area will be required to better understand the
relationships between the various cultural/environmental factors
and test performance.
ACKNOWLEDGMENTS
This study was supported in part by grants from the US Department of
Education–National Institute on Disability Research and
Rehabilitation–The Traumatic Brain Injury Model Systems Project
(H133A970021). A portion of this study was conducted as part of the
first author's doctoral dissertation thesis. The authors would
like to thank B.P. Rourke, M. Kral, S. Ramcharan, and J. Manly for
their helpful comments in the conducting of this research project. We
would also like to thank M. L. Rohling for his help with the OTBM.
Portions of this paper were presented as part of the Division 40
program at the American Psychological Association Convention in
Toronto, Ontario, Canada, Aug 7–10, 2003.
