Cultural Differences in Pain Expression

1. Cultural Differences in Pain Expression Nancy Alvarado California State Polytechnic University, Pomona

2. Coauthors • Ralph B. JesterUniversity of California, Irvine • Christine R. HarrisUniversity of California, San Diego • Julia F. WhitakerUniversity of Utah, Health Sciences Center • Funded by NIH MBRS/SCORE Grant S06 GM053933, 2006-2009

3. Undertreatment for Pain • Chart review studies suggest routine under medication for pain of members of ethnic and racial minority groups in the USA. • This occurs regardless of the type of injury or medical condition, for both chronic and acute pain.

4. Why does this happen? • Are members of such groups different in their: • Self report • Expressive behavior (including facial expression) • Physical reactivity (heart rate, blood pressure) • Pain tolerance • Or is the difference with the observers?

5. Our Study • Multiple measures: • FACS coding of videotaped behavior • Pain attitudes questionnaire assessing cultural beliefs about pain and its expression • Physiological measures • Self-report using multiple scales • Acculturation questionnaires • Only FACS results are presented today.

6. Pain Evoked by Cold Pressor • Subjects immersed left hand up to wrist in circulating cold water: • Held at 3 degrees Centigrade (+- .2) • Hand removed when subject could no longer tolerate the cold or reached the time limit (3 min.) • The colder water temperature was used to minimize sex differences.

7. Subjects • Four self-identified groups were tested: • Asian American • African American • Hispanic • European American (dominant culture) • ~50 subjects per group, Cal Poly students • 25 male, 25 female

8. Coding Method • FACS – all AUs except head position and eye movements (Ekman & Friesen, 1978). • Frequency of occurrence, presence or absence of each AU by subject, duration not coded. • Events – as described by Ekman & Rosenberg (1997). What the Face Reveals. • Co-occurrence of AU 1+4, 4+7, 1+2, and 6+12 was also coded.

9. Predictions • We expected to find expressive differences related to subculture and sex. • We expected: • Asian Americans and Hispanics to be more stoic (less expressive) • African Americans to be more expressive. • Men to be less expressive than women.

10. Results • No strong sex differences in expressivity were observed, F(1,173)=2.56, p=.110. • No differences in events across cultural groups were observed, F(3,173)=0.66, p=.580. • Discriminant analysis showed better than chance prediction (group=45.3, sex=71.3), improved with segregation by acculturation

11. Expected Pain AUs • The AUs found in previous pain studies were found here, equally in all four groups. • Distress expressions (AU 1+4) were more frequent among African American women. • Hispanic men showed more frowns (AU 4+7) and fewer smiles (AU 6+12) than Hispanic women.

12. Larger Sex Differences Were Found Among Hispanics for Smiling

13. Frowning Showed Similar Results

14. Distress Expressions also Varied

15. Smiling • Both Duchenne and non-Duchenne smiles occurred during the pain experience – with no experimenter present. • Smiling often occurred just before a subject signaled to remove the hand from the water.

16. Duchenne vs Non-Duchenne Smiles

17. Smile Types by Sex and Group

18. Conclusions • Cultural differences occurred in more general AUs (frowns, smiles, AU 1+4) not in pain AUs (grimaces, lip presses, AU 9 or 10). • Culture may influence social interaction more than expressivity directly related to pain. • Because results were stronger for less acculturated subjects, members of the wider community may show larger differences. • Our study lacked power – more subjects needed.