Running head: COLOR MODIFIER USE IN TWO LANGUAGES



Running head: CULTURAL DIFFERENCES IN PAIN EXPRESSION

Cultural Differences in Pain Expression in a Cold Pressor Task

Nancy Alvarado

California State Polytechnic University, Pomona

Ralph B. Jester

University of California, Irvine

Christine R. Harris

University of California, San Diego

Julia F. Whitaker

University of Utah, Health Sciences Center

Author Contact:

Nancy Alvarado, Ph.D.

Department of Psychology and Sociology

California State Polytechnic University

3800 W. Temple Ave.

Pomona, CA 91768

Phone: (909) 869-3896

Email: nalvarado@csupomona.edu

Key words: acute pain; pain assessment; racial and ethnic differences; under-treatment of pain, cold pressor, pain facial expression

Abstract

Cultural Differences in Pain Expression in a Cold Pressor Task

Numerous studies have documented that members of ethnic and racial minority groups, and women, are more likely to be under-treated for pain (Bonham, 2001; Weisse, Sorum & Dominguez, 2003; Hoffman & Tarzian, 2001). Under-treatment has been reported in emergency treatment of bone fractures (Todd, Deaton, D’Adamo, & Goe, 2000; Todd, Samaroo & Hoffman, 1993), cancer pain (Cleeland, Gonin, Baez, Loehrer & Pandya, 1997; Cleeland, Gonin, Hatfield, Edmonson, Blum, Stewart & Pandya, 1994), and postsurgical care (McDonald, 1994). Further, even when treated, they are less likely to be given stronger opioid drugs (Pletcher, Kertesz, Cohn & Gonzales, 2008). Williams (2002; Kappesser & Williams, 2002; Kappesser, Williams & Prkachin, 2007) suggested that this under-treatment may arise from physician bias, a tendency to underestimate a person’s pain and thus under-prescribe pain medication, or even misdiagnose the underlying condition. Prkachin (Prkachin, Berzins & Mercer, 1994; Prkachin, Mass & Mercer, 2004; Prkachin, Solomon, Hwang & Mercer, 2001) documented a systematic underestimation of pain that was greater among experienced health care providers than untrained observers. He and his colleagues demonstrated that the actual facial movements of a pain expression increased with greater self-reported pain, providing a read-out that was accurate at high intensities of pain, less so at lower intensities. However, despite this perceptual information, physicians displayed an underestimation bias when physician pain ratings were compared to sufferer pain ratings on the same rating scale. This suggests that physicians may observe pain expressions but discount them, placing less reliance on them than untrained observers do. In this research, we explored reasons for the observed under-treatment of pain and accompanying physician underestimation bias. Specifically, we investigated whether members of racial and ethnic minority groups (here called subcultures) were likely to show differences in their pain expressivity, self-report or physiology that might be misinterpreted by physicians and result in under-treatment for pain.

The tradeoffs between detection of malingering and accurate appraisal of pain may contribute to physician underestimation bias (Williams, 2002). When physicians become too suspicious, their failure to accurately assess pain may contribute to a vicious circle in which chronic pain sufferers exaggerate their pain in order to be adequately treated while physicians respond to the exaggeration by increasingly discounting their expressions of pain. Studies of chronic pain sufferers suggest that individuals may over time exaggerate their expressions in order to more effectively communicate with health care deliverers, even showing pain expressions when no pain is felt (Prkachin, Berzins & Mercer, 1994; Prkachin, 2005). Chronic pain sufferers are most often suspected of malingering (Mendelson & Mendelson, 2004). Historically, physicians have been suspicious of higher pain reports. Mendelson & Mendelson (2004) review historical attitudes toward malingering. They cite Hackett (1971), who described a prejudiced physician attitude toward patients in pain, and Miller & Cartlidge (1974) who defined malingering as not only simulation of disease or disability not present, but also, a much more frequent gross exaggeration of minor disability. Mendelson & Mendelson (2004) stated, “Given the subjective nature of pain, it therefore becomes problematic to determine what would be the “expected” extent of pain associated with a particular physical lesion…” (p. 425). Physicians are reported to become less sympathetic, even angry, if they believe that patients are exaggerating their pain symptoms or reports (Poole & Craig, 1992; Prkachin & Craig, 1995). Keefe & Dunsmore (1992) noted, “Conscious efforts to communicate pain through guarded movements, facial expressions, or extreme ratings of pain upset and even enrage clinicians.” (p. 97, quoted by Prkachin & Craig, 1995, p. 202).

Thus, difficulties can arise for members of minority subcultures if their experience of pain is divergent from that of the majority of patients, or if their expressivity is different. Such differences may lead physicians to suspect dissimulation and give rise to discounting of self report or facial expression or even suspicion of malingering. The actual experience of pain among minority group members is not as well studied as among non-minorities. For example, opioid-induced hyperalgesia (a greater sensitivity to pain-inducing experience) may be expected to affect minority group members differentially if their exposure to such drugs differs from that of other groups. Recent investigations suggest that real differences exist in pain experiences among African American; Hispanics, and Asians (Lipton & Marbach, 1984; Edwards & Fillingim, 1999; Breitbart & McDonald, 1996; Sheffield, Biles, Orom, Maixner & Sheps, 2000; Bates, Edwards & Anderson, 1993; Brena, Sanders & Motoyama, 1990; McCracken, Matthews, Tang & Cuba, 2001; Weisenberg, Kreindler, Schacht & Werboff, 1975; Barak, Weisenberg, 1988; Faucett, Gordon & Levine, 1994; Sternbach & Tursky, 1965). Greater awareness of sex differences in pain experience has led to a consequent correction in physician expectations (Weisse, Sorum & Dominguez, 2003). Differences in emotional response to clinical situations, including pain-related anxiety, have also been documented in African American patients (Fillingim, Edwards, & Doleys, 2002; McCracken, Matthews, Tang & Cuba, 2001). These studies suggest that increased ratings of pain can result from an increased experience of pain, not solely from a tendency to describe pain differently or to use rating scales differently.

Stereotypes about the expression of pain complicate actual differences in pain experience and report. Early research in pain expression had no method for objectively and systematically describing facial action, as now exists with Ekman and Friesen’s Facial Action Coding System (FACS) (1978). As with early research on emotional expressions, studies of pain expression were often impressionistic rather than scientific. Studies of “Yankee” (Northeastern American) and Jewish subgroups (Tursky & Sternbach, 1967; Sternbach & Tursky, 1965) contributed to today’s general belief that ethnic groups may have characteristic styles of pain expression. Yankees were considered stoic whereas Mediterranean people were described as “dramatic.” With the advent of better methods for characterizing facial activity, the issue of styles or dialects of expression can be more rigorously addressed. For example, Asians are stereotypically thought to be more stoic than European-Americans (Chang, 2003). Recent attempts to study this using infant facial expression showed mixed results for Japanese and Chinese or Chinese-Canadian infants compared to non-Asian infants (Rosmus et al., 2000). Further, it is unclear whether culture can strongly modify facial expression. Learning-based models of facial expressivity attribute cultural differences to socialization, yet attempts to modify facial expression were unsuccessful for adults modeling tolerance and intolerance of pain (Craig & Patrick, 1985). A conflicting study in which mothers modeled pain behavior to their children (Goodman & McGrath, 2003) confounded heritability with modeling. More recently, the ability to both enhance and suppress expression has been associated with successful coping with adversity (Bonanno et al., 2004). As with many characteristics, larger variability in expressivity exists within a cultural group than between groups (Prkachin, 1992; Prkachin & Craig, 1995).

Whether cultural differences in expression exist or not, wide individual variability implies that an entirely genuine pain response may be inappropriately treated if the physician holds mistaken expectations about the amount of pain a patient should be expressing. A mistaken expectation may arise from a misunderstanding of real differences in pain experience coupled with triggered stereotypic beliefs about minority pain. To complicate matters, stereotypes differ for males and females due to different gender roles in some subcultures. For example, Hispanic patients are stereotypically judged as histrionic or overly expressive, especially when female. An expressive Hispanic man may be judged as malingering because his expressions are inconsistent with expectations about macho stoicism. Or he, himself, may conceal and under-rate his own pain because he considers it unmanly to reveal pain. African-American and Asian stereotypes have historically included insensitivity to pain as part of the justification for mistreatment during enslavement or “Coolie” indentured servitude (Chang, 2003). Such stereotype-driven expectations conflict with the observed greater sensitivity to pain reviewed above. Physician attitudes about malingering or misuse of emergency room services by immigrant groups such as Hispanics and Asians with low socioeconomic status may contribute to resentment and lessened sympathy among physicians. Further, immigrant patients may believe that the way to be a “good patient” is to suffer without complaint, leading to misdiagnosis or under-treatment.

Studies of pain deception show that adults and children can more readily exaggerate than suppress pain facial expressions (Poole & Craig, 1992; Larochette, Chambers & Craig, 2006). When there is a discrepancy between self-report of pain and facial expression, physicians give greater credence to the facial expression (Prkachin & Craig, 1995; Poole & Craig, 1992). They believe that self-reports are easier to fake than facial expressions. This reliance on facial expression is problematic because of the large individual differences in expressivity. Prkachin & Craig report “At severities at which the pain was reported to be substantial, 13-50% of subjects displayed no facial evidence.” (p. 194; Wilkie, 1995). How are facially inexpressive patients who self-report strong pain treated when they are members of an ethnic minority? It seems likely that there is a difference in the potential for under-treatment when inexpressivity is stereotype-congruent rather than stereotype-incongruent. These questions have not been investigated.

In the face of such complexities, it would be useful to identify a “gold standard” for assessment of pain. Pain is typically assessed using multiple indicators, including physical responses such as tachycardia, blood pressure reactivity, muscle rigidity, and behavioral measures such as self-report (verbal and “Oucher” or “Face” scales), guarding, and facial expression (Jensen & Karoly, 2001). However, use of indicators such as tachycardia and blood pressure reactivity is frequently prevented by advanced age, hypertension (which is anti-nociceptive), beta blocking or hypertension medication, or presence of narcotics, leaving the physician reliant on facial expression and self-report. Self-report is given strong weight except where patients are suspected of medication seeking or malingering (McCaffery, 1979; Mersky, 1979), but Poole & Craig (1992) note that self-report is affected by situational factors and incentives. Further, self-report may be unreliable when patients are infants, children or elderly, when conscious introspection is impaired, or when patients cannot speak or communicate effectively, increasing reliance on facial expression of pain. Further, self-report scales are subject to a variety of anchoring, retrospective and other scale biases, only now being investigated. Some researchers suggest that under-treatment of pain might be reduced if facial expression were preferred to other indicators (Williams, 2002; Prkachin, 2007).

Accurate estimation of pain may be accomplished using facial expression, but only if physicians use the cues actually present in the face instead of relying upon beliefs about pain (Prkachin, Berzins & Mercer, 1994). Poole & Craig (1992) demonstrated that observers tended to give more weight to a person’s pain facial expression than to their pain statements, even when the expressions were faked or suppressed and thus inaccurate. Hill & Craig (2004) suggested that individuals can be trained with feedback to more accurately assess pain facial expressions, whereas information-based training was unhelpful. Unfortunately, many individuals are facially inexpressive or show incongruence between facial expression and other pain indicators, making the use of facial expression as a gold standard problematic for many sufferers.

Although physicians routinely deal with pain, they may not be pain experts. Because assessment of pain is generally a holistic judgment with several inputs, physicians may be unaware of the extent to which their own cultural stereotypes and beliefs can affect their interpretation of pain indicators. As Prkachin & Craig (1995) noted, even when beliefs about pain are explicit, “Stereotypes fail to recognize tremendous within-group differences and small between-group differences that call into question their utility.” (p. 198). Thus, understanding the nature of real and assumed differences among groups is crucial to: (a) accurate interpretation of pain self-report and facial expression; and (b) accurate identification of medication-seeking, malingering and other deception. Optimal treatment for members of minority subcultures relies upon accurate estimation of pain whichever indicators are used.

This research used multiple measures to assess pain expressivity on a cold pressor task across four subcultures within the student population: (1) African Americans; (2) Asian Americans and Asian immigrants; (3) Hispanic; and (4) European Americans. The dependent variables included: (1) autonomic measures; (2) facial expressivity; (3) self report using several types of scales; (4) measurement of pain attitudes by questionnaire; and (5) measurement of acculturation by questionnaire. Our goal was to examine similarities and differences on these measures across the four groups, to examine coherence among the measures within groups, and to identify any differences that might be linked to stereotypes or the systematic under-treatment among physicians and other health care professionals. We predicted that cultural beliefs would mediate pain expressivity (facial expression) and self report and that we would find greater stoicism within the Hispanic and Asian groups and greater expressivity among African Americans. We further predicted that women would be more expressive than men, based on their greater expressivity in other facial expression studies and the greater acceptance of complaint about physical discomfort permitted of women within many cultures. Specific hypotheses are noted where appropriate in the Results section.

Method

Participants

Our intention in this study was to recruit students in order to limit prior experience and increase the likelihood of finding healthy subjects without chronic pain or drug use. Participants are listed in Table 1 by sex and ethnicity. All subjects were students at the California State Polytechnic University, Pomona, ranging in age from 18 to 53 (mean = 22.1, sd = 4.0). Subjects were included in the data analysis only if they had complete data on all measures. Most subjects were recruited using an online human subjects pool signup system and were given course credit. Due to difficulty recruiting sufficient participants via the subject pool, some African American and Asian American male subjects were recruited from campus locations via flyers and were paid $10 for their participation. Subjects were screened for health problems that might interfere with their ability to experience pain or produce facial expressions (e.g., high blood pressure, schizophrenia or depression). Individuals currently taking pain medication or medications that might alter autonomic response were also excluded.

Materials

The cold pressor task was administered using a Jeio Tech RW-0525G refrigerated circulating bath which maintained water temperature at 3o Centigrade within two tenths of a degree. A Biopac MP100WS psychophysiological recording system was used to record heart rate, blood pressure and electrodermal activity. A Vasotrac system was used to continuously measure blood pressure via a wrist cuff. A Sony 900 digital video camera was used to record facial expressivity during a 10 minute baseline and throughout the cold pressor task.

To assess pain attitudes, a review of the literature on cultural beliefs about pain was conducted. This resulted in a series of questions that were presented to four focus groups, asking subjects about their family attitudes and beliefs about pain. From this, an exploratory pain attitudes questionnaire was developed, consisting of 63 questions assessing different aspects of belief about pain and its appropriate expression. A more detailed description of the focus group and questionnaire results is reported by Englert, Jester, Alvarado, Harris and Whitaker (2009).

Self-report rating scales included a series of seven-point scales anchored by emotion terms, the McGill Pain Inventory, and a seven-point pain rating scale. Acculturation was measured using an inventory appropriate to each subject’s self-described cultural background. For Asian Americans, we presented the SL-ASIA (Suinn, Rickard-Figueroa, Lew, & Vigil, 1987). For Hispanics, we presented the Short Acculturation Scale for Hispanics (Marin, Sabogal, Marin, Otero-Sabogal & Perez-Stable, 1987). For African Americans, we presented the revised African-American Acculturation Scale AAAS-R (Klonoff & Landrine, 2000). FIX Two scales were used to assess African American acculturation, one based on adherence to cultural practices within the African American subculture, the other based on attitudes toward European Americans. The European American scale was the counterpart to the latter and largely concerned attitudes toward African Americans. The Hispanic and Asian American acculturation scales were largely based on languages spoken and participation in activities within the subculture.

Procedures

After informed consent and screening for inclusion, subjects were asked to wash their hands and remove any jewelry or watches. They then were seated inside a cubicle in a chair facing a screened video camera (to minimize its salience) while an experimenter affixed sensors to monitor heart rate at ankles and wrist. The Vasotrac wrist cuff and a finger sensor for electrodermal activity were attached. Following that, the subject was left alone for a 10 min videorecorded baseline period to permit the subject to accustomed used to the camera and presence of the sensors. The experimenter then returned. A doorbell-type signal was placed in the participant’s right hand and the experimenter asked the subject to press it, to demonstrate its operation. The subject was instructed to press the signal button at the first sign of pain and again when the pain became intolerable and they wished to remove the hand from the water. Subjects were asked to tolerate the water as long as possible, but were also told they could remove the hand whenever they wished. The experimenter left the cubicle and from outside told the subject to “go” (start the task) by placing his or her hand in the cold water up to the wrist, with fingers open but not touching the sides or bottom of the tank. The experimenter was seated behind a screen outside the cubicle and recorded the start, first signal and second signal on the Biopac record. When the signal button was pressed for the second time (or the subject removed the hand), the experimenter returned and dried the hand with a towel. If the subject did not press the second button by the end of 3 minutes, the experimenter returned and ended the task. Immediately following the task, the subject was asked to complete the McGill Inventory on a clipboard and rate the pain. Following that, the subject was moved to a computer to complete the other rating scales and inventories. Pain and emotion ratings were presented first, followed by the pain attitudes questionnaire and then the acculturation questionnaire, followed by a debriefing. If the subject tolerated the pain for 3 minutes (timed out), the experimenter asked follow up questions about that during the debriefing.

Results

Cold Threshold and Tolerance

The cold threshold was measured as the time from first immersion in cold water to the time the signal button was pressed for the first time, to signal the experience of pain. Cold tolerance was measured as the time from the first button press to signal pain until the second button press to request removal of the hand from the water. A time-out was recorded when the subject left the hand in the water for 3 minutes, at which time the hand was removed by the experimenter. No significant differences were found across the four subcultures for threshold, tolerance, or total time in water. However, 12 timeouts were observed in the European American group compared to 6 for Asian American and 4 for the other groups, which contributed to a nearly significant difference in total time in water, F(3,179)=2.126, p=.099, but did not affect tolerance or threshold. Examining the debriefing responses, this higher number of timeouts appeared to be related to the number of athletes in the European American group. They reported surfing and swimming in cold water or using cold water hydrotherapy to treat sports injuries. They may also have been more likely to regard the pain manipulation as a challenge or competition. With all timeouts removed, there was no significant difference in mean pain threshold, tolerance or total time in water across groups. A consistent sex difference was found for threshold, t(181)=4.188, p=.000 and total time in water, F(1,155)=7.715, p=.006, but no significant difference was found for tolerance, t(181)=1.265, p=.207.

Biophysiological Measures

Physiological measures were used for two purposes: (1) to verify that participants experienced pain during the cold pressor task; and (2) to determine whether any group showed significant differences in physiological response. Christine please add results here

Pain and Emotion Ratings

Participants rated pain and a series of emotions using seven-point rating scales, including: happiness, anger, fear, anxiety, frustration, embarrassment, calmness, sadness and surprise. No significant differences were found across the four subcultures on any of these scales (p < .05). Significant gender differences for happiness, excitement, pain and embarrassment were found (see Table 2). When ratings were normalized within sex, no significant differences were found across subcultures. Similarly, when ratings were normalized within subculture, no significant differences were found by group, but the sex differences remained significant. Although no other significant differences were found after normalization, a trend was observed in which Asian American participants showed smaller sex differences in their ratings compared to the other three groups, while Hispanic and African American groups showed consistently larger sex differences, suggesting that sex roles affected ratings more for those groups than for Asian Americans and to a lesser extent, European Americans, as illustrated in Figure 2.

Participants also rated the quality of their experience using the McGill Pain Inventory. It includes rating scales anchored by a series of descriptive terms including: throbbing, shooting, stabbing, sharp, cramping, gnawing, hot or burning, aching, heavy, tender, splitting, exhausting, tiring, sickening, punishing, cruel, fearful and painful. The inventory is scored by combining subsets of these scales to produce a sensory subscale and an affective subscale. Significant differences were found on the sensory subscale, by group, with African American and Hispanic participants of both sexes reporting higher scores, F(3,159)=2.878, p=.038. Significant differences were also found by gender, with female participants consistently reporting higher scores than males, F(1,159)=12.399, p=.001. There was no significant interaction between sex and ethnicity, F(3,159)=.403, p=.751. For the affective subscale, no significant main effects were found, but a significant interaction between gender and subculture was found, F(3,172)=2.958, p=.034. This occurred because Asian American and European American female participants gave higher ratings than males whereas Hispanic and African American males gave higher ratings than females. Thus the pattern of results for the sensory subscale was considerably different than the affective subscale, as shown in Figure 3.

In medical contexts, patients are frequently asked to estimate the amount of pain they are willing to withstand using a ten-point scale. Our participants were asked to do the same. After the pain manipulation, they then rated their pain using the same ten-point scale, permitting a comparison of the anticipated and actual experience. The scale, as in medical contexts, was labeled discomfort. The estimates were significantly correlated with the experienced discomfort, r=.50, p=.000 but there was a significant difference between the estimated and experienced ratings, F(1,137)=8.413, p=.005. All participants tended to overestimate the amount of “discomfort” they would be willing to withstand. There were no significant differences between subcultures and no significant interactions. There was a significant sex difference, with males producing higher estimates than females and a greater discrepancy between their estimated and actual ratings, F(1,137)=14.107, p=.000. Ratings by sex and subculture are compared in Figure 4. Interestingly, both the discomfort estimates and the actual discomfort ratings are uncorrelated with the ratings made using a scale labeled “pain” immediately after the task, r=-.095 for estimated discomfort and r=-.003 for actual discomfort.

Pain Attitudes Questionnaire

Although space does not permit a detailed analysis of the responses to the Pain Attitudes questionnaire developed for this study (see Englert et al., 2009), an analysis of the responses for each question showed that seven questions produced significant differences across groups. These are listed in Table 2. To determine whether culture affected responding, a discriminant analysis was used to classify subjects into subcultures based upon their questionnaire responses. Because the group sizes were unequal, prior probabilities were computed from the group sizes during the analysis. Those who had timed out were excluded. The discriminant analysis classified participants into their self-identified subcultures with 81.1% accuracy. When sex was used as the grouping variable, subjects were classified with 86.7% accuracy. To explore the impact of culture on responses, subjects were divided into high and low acculturation groups using a median split of their acculturation inventory scores. Those with high acculturation scores were considered to be closer to the mainstream culture and those with low scores were considered to be closer to their subculture. The discriminant analysis was then run again on each of these two subsets of participants. The two separate groups of subjects classified by acculturation both were correctly classified with 98.6% accuracy, however, the groupings are tightly clustered (more cohesive) for the less acculturated subjects, as can be seen in Figure 5a. The improvement of classification accuracy when acculturation is used to partition the sample demonstrates that cultural attitudes toward pain do differ in ways that characterize each group. The questions that were most important as discriminators are generally those that produced significant differences between scores (see Table 2). However, in addition to the items in Table 2, the following questions were important to the discriminant analysis: (1) People who have suffered great pain are to be admired; (2) I avoid the doctor because I am concerned that they might find something truly wrong with me; and (3) There is no point to complaining when in pain. These questions had significance levels of .07 using one-way ANOVA. Overall, groups differed along dimensions of expressivity and stoicism, with Asian Americans reporting the least expressivity and the most stoicism, and African Americans showing the greatest expressivity and the strongest belief that pain is important during medical treatment (see Table 2).

Facial Expression

Facial activity during a ten minute baseline and during the cold pressor task was videorecorded. Facial expressions were coded during the entire duration of the cold pressor task. A comparable baseline period of equal duration was also coded, immediately before the end of the baseline during the time when the subject was assumed to be most accustomed to the presence of the camera. Ekman and Friesen’s (1978) Facial Action Coding System (FACS) was used to identify facial movements associated with pain in previous research. These movements, called action units (AUs) were compared in two ways: (1) mean number of each AU per subject; and (2) number of subjects showing the presence or absence of each specific AU. Overall facial activity was also measured by coding the number of events (co-occurring patterns of facial activity) per subject (Ekman & Rosenberg, 1997). Representative pain expressions are shown in Figure 6. No differences across groups were found for the AUs most frequently associated with pain (e.g., AU 20, 9, 4+7, Craig & Patrick, 1985). No differences in the mean number of events were found across groups, F(3,173)=0.66, p=.580 or by sex, F(1,173)=2.56, p=.110, suggesting similar levels of expressivity. A discriminant analysis using all AUs as input variables correctly classified subject by group with 45.3% accuracy (25% is chance) and by sex with 71.3% accuracy (50% is chance). Further analysis showed that AUs related to affect, not pain, accounted for group differences, with an interaction between sex and subcultural group. While the results were not significant, African American women were more likely to show AU 1+4 (characterized as a distress expression), Hispanic and African American women were more likely to smile when in pain (AU 1+6), and Hispanic men were more likely to frown (AU 4+7). The frequency of smiling during pain was higher for women than men, F(1,173)=3.893, p=.050. Rates of smiling and frowning by group are shown in Figure 7. As can be seen, Hispanic males and females showed the greatest sex difference in expressive behavior, while Asian American males and females showed the greatest similarity. There was a slight, nonsignificant trend toward less expressivity for Asian American subjects across all types of AUs. No significant gender/ethnicity interactions were found.

Discussion

The multiple measures used in our study present a complex picture in which some measures show significant differences while others do not, but a pattern emerges. The high acculturation of our college student sample may have prevented finding strong cultural differences that may exist in more isolated communities and older immigrant groups. Nevertheless, we found significant differences related to culture in the attitudes and beliefs about pain and in the self-report and expressive behavior related to affect but not pain. No physiological differences were found across subcultures, suggesting that the pain experience was similar from a physical standpoint but different emotionally.

Based on our physiological measures, we are confident that our subjects experienced strong pain. Excluding the timeouts which occurred when subjects approached the time-limited cold pressor task as a competitive exercise, no group appeared more or less willing to tolerate pain and thresholds for feeling pain were the same across groups. We did find the sex differences noted in previous studies, present within each of our cultural groups. The cultural differences observed were found in facial expression related to affect (smiling, frowning, distress), as classified by Ekman and Friesen (1978). The significant differences across subcultures were also found in the self report of emotional states (happiness, embarrassment, anger) and in the McGill affective subscale (not the sensory subscale). We found significant differences in attitudes and beliefs about pain, largely along dimensions related to expressivity, expectations for physicians, and the value of stoicism.

We found some support for the stereotype that Asian American are more stoic, but believe this is related to attitudes and cultural norms about expressing pain. Asian subjects did not choose swearing as an appropriate expression of pain for anyone (e.g., self, mother, father), although all three other groups did. They were the only group to select “shake it off” as a mother’s response to a cut hand. Although the difference was not significant, Asian American subjects were consistently the least expressive facially (see Figure 7). Asian American subjects were more likely to disagree that pain should be important to physicians and less likely to expect pain treatment (see Table 2). Sex differences in the use of pain and affect ratings scales were smallest for Asian American subjects.

In contrast, African American subjects seemed to value pain expression more and were more expressive during the task. They agreed most strongly with the importance of physicians treating pain, were more likely to express pain even in contexts where a job might be lost, and tended to rate pain higher using the rating scales. They also showed more facial expressivity, although this was a non-significant difference. African American women showed more frequent distress expressions (AU 1+4) than any other group. African American subjects were more likely to expect pain relief as part of medical treatment, despite also stating that doctors were more likely to suspect them of medication seeking.

Hispanic subjects showed large sex differences, both in rating scale usage (see Figure 3) and in facial expressivity (see Figure 7). This suggests that culture-related gender roles may dictate differences reflected in expectations and behavior for Hispanic subjects. The impact of stereotypes about machismo did not produce suppression of expression, as expected. Instead, there appeared to be suppression of positive affect and greater frowning, rather than in greater stoicism overall. Hispanic subjects were nearly as expressive as African Americans and more expressive than European Americans. There was no observed tendency to tolerate pain longer or to rate pain as less severe, as might be expected given macho stereotypes. There may have been a tendency to exaggerate pain, perhaps to compensate for inability to withstand the cold for as long as desired. Greater embarrassment was reported for Hispanic and African American males, perhaps related to their failure to tolerate the cold for the entire three minutes.

Although the difference was not significant, we observed that Hispanic and African American women were more likely to smile when in pain. Smiling may be related to embarrassment or shame, emotions that may arise in medical settings (Miller, 1996; Harris, 2006). This is important because physicians may believe that someone who is in pain would not smile and thus discount their self-reported intensity of pain. Women are also an undertreated group (Weisse, Sorum & Dominguez, 2003) and it may be that the increased smiling among women in general, and minority women in particular, may account for much of the observed under-treatment. This would not account for the under-treatment among Asian patients reported in the literature, but it may be that different explanations apply to different groups.

The presence of smiling while in pain by both males and females during this task was unexpected. Such smiling may be related to embarrassment or shame, emotions that may arise in medical settings. In particular, males seemed to smile right before removing their hands from the water, perhaps as an acknowledgement that they had to give up (Keltner, 1995). Smiling may be a coping mechanism when feeling embarrassment or shame (Keltner & Anderson, 2000; Keltner & Buswell, 1997). Subjects were seated alone in a cubicle during the cold pressor manipulation to minimize social interaction, so they were not smiling at anyone or in supplication at any person. If physicians believe that smiling always indicates pleasure or the absence of pain, this is a serious misunderstanding of the nature of pain expression.

Several factors worked against finding significant differences across groups. First, we kept water temperature at 3o centigrade. Lower water temperature tends to reduce sex differences (CITE) by making it more difficult to tolerate pain in service of other goals. We believe that may have impacted cultural self-expectations in similar ways. Second, although diverse, our subjects are well-acculturated and many are psychology majors. They have been well-educated about culture and gender roles and that may have influenced their responses. The differences observed in this study are most likely the hardiest remaining after socialization into the mainstream culture. We would predict that greater differences would be observed in studies of less acculturated samples. Even so, attitudes and beliefs about pain were sufficiently different that subjects could be classified by their responses into cultural groups with high accuracy. That suggests that culture is an important mediator of pain experience and behavior in medical settings. Beliefs and attitudes do influence emotional response and it is well known that emotion, in turn, influences pain experience. If the strongest impact of culture is on emotion rather than pain, it is still important to address such differences in medical practice.

Our findings suggest that it would be worthwhile for physicians to take into account cultural differences when assessing pain. African American patients may be more expressive as a group, without being suspected of intentionally exaggerating their behavior. Asian American patients may be less expressive while feeling stronger pain than would be indicated by the same behavior in someone from a different culture. Hispanic males may frown when in pain while Hispanic females may smile and show little negative affect despite pain. European Americans are more likely to tell you about their pain. Because cultural differences appeared to have less impact on pain expression (grimacing, nose wrinkling, eye tightening), it may be worthwhile for physicians to learn to attend to these independent of affective expression (smiling, frowning). Finally, the 10-point discomfort scale used by many hospitals showed little relation to the various pain ratings and facial expressions in our study. All groups tended to overestimate the amount of pain they were willing to tolerate, with greater accuracy for females than males. More seriously, subjects tended to interpret the label “discomfort” to mean something different than “pain.” If physicians are using the term discomfort as a synonym for pain our results suggest there may be serious miscommunication.

The need for improved pain assessment is especially pressing today as the Joint Commission on Accreditation of Healthcare Organizations (2000) has called for the monitoring of pain as a fifth vital sign and made effective pain control part of hospital accreditation standards. Consideration of these, and similar, cultural influences on pain expression can and should be incorporated into physician training to improve accuracy of pain assessment.

References

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Author Notes

Send correspondence to: Nancy Alvarado, Department of Psychology and Sociology, California State Polytechnic University, Pomona, 3801 W. Temple Avenue, Pomona, CA 91768. We thank Phyllis Ann Englert, Noriko Coburn, Yvonne Burgos, Ruben Hoyos, and the many undergraduate students who assisted with this research. This research was supported by NIH MBRS/Score Grant S06 GM053933.

Table 1. Participants included in data analysis.

Female Male Total

African American 17 15 32

Asian American 25 25 50

European American 22 26 48

Hispanic 29 24 53

All Groups 93 90 183

Table 2. Pain Attitudes Questionnaire items showing significant differences across subcultures.

|Item |African American |Asian American |Hispanic |European American |F or χ2 |p |

|If you were walking and you came across a |3.69 (1.36) |4.42 (1.47) |3.68 (1.60) |3.92 (1.22) |2.80 |.041 |

|person who had just bumped into a very sharp| | | | | | |

|object, and they showed no reaction at all, | | | | | | |

|what would you think of them? (1=disapprove,| | | | | | |

|7=approve) | | | | | | |

|If your mother cut her hand while working |Bandage it and go |Bandage it and go |Bandage it and |Bandage it and go |51.83 |.042 |

|around the house, what would she be most |back to work, |back to work, |go back to work,|back to work, | | |

|likely to do? |scream or yell, |scream or yell, |swear, scream or|swear, scream or | | |

| |tell you how much |shake it off |yell, cry, ask |yell, tell you how| | |

| |it hurt | |for help |much it hurt | | |

|I expect the doctor to listen to me when I |6.66 (.70) |5.96 (1.18) |6.5 (.98) |6.23 (.99) |4.04 |.008 |

|talk about my pain. (1=disagree, 7=agree) | | | | | | |

|Pain relief is a major part of medical |5.59 (1.29) |4.74 (1.59) |5.25 (1.29) |4.94 (1.31) |2.90 |.036 |

|treatment. (1=disagree, 7=agree) | | | | | | |

|Doctors assume that everyone from my ethnic |2.91 (1.63) |2.08 (1.32) |2.42 (1.77) |1.58 (.90) |6.04 |.001 |

|background is seeking pain medicine to sell | | | | | | |

|on the street. (1=disagree, 7=agree) | | | | | | |

|There is a difference between being in pain |6.03 (.97) |5.46 (1.30) |5.79 (1.20) |5.25 (1.30) |3.33 |.021 |

|and being injured. (1=disagree, 7=agree) | | | | | | |

|I do not tell others when I am in pain |2.69 (1.64) |3.30 (1.75) |2.62 (1.48) |3.37 (1.63) |2.77 |.043 |

|because I might lose my job or my place on | | | | | | |

|an athletic team. (1=disagree, 7=agree) | | | | | | |

Figure Captions

Figure 1. Pain experience results (total time in water with timeouts excluded) showed no difference by ethnicity but a consistent sex difference for all four groups.

Figure 2. Standardized self-report ratings within subculture show that African American and Hispanic males report greater embarrassment during the cold pressor task.

Figure 3. McGill ratings showed a different pattern of results for the sensory and affective subscales.

Figure 4. Males and females in all four groups predict they can withstand more discomfort than they are willing to tolerate.

Figure 5. Less acculturated subjects (top) are more readily classified by subculture based on their pain attitudes than highly acculturated subjects (bottom).

Figure 6. Representative facial expressions during the cold pressor task for the four subcultures (top to bottom: African American, Hispanic, Asian American and European American).

Figure 7. Males frowned more frequently whereas females smiled more frequently when in pain, with larger sex differences for Hispanic subjects.

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