What factors fuel racial bias in pain perception and treatment?: A meta-analysis across 40 experimental studies Jingrun Lin1, Alexis Drain2, Azaadeh Goharzad2, and Peter Mende-Siedlecki2 1Department of Psychology, University of Virginia 2Department of Psychological & Brain Sciences, University of Delaware Declarations This research was supported by the National Science Foundation (BCS-1918325 to PMS) and the National Institute of General Medical Sciences (5P20GM103653-08; Junior Investigator: PMS). JL, AD, AG, and PMS participated in design and data collection, JL and PMS conducted the meta-analyses, JL composed the first draft, all authors edited the manuscript. All experiments in the internal meta-analysis were approved by the Institutional Review Board at the University of Delaware or New York University, in accordance with the Declaration of Helsinki. All participants gave informed consent. All materials are available online (https://osf.io/w7uak/). We have no conflicts of interest to disclose. Author Note We acknowledge the hard work of our lab’s research assistants, particularly Sloan Ferron, Chris Gibbons, Nicole Kozak, Dustin Prusisz, and Dani Schwartz. We also thank Jin X. Goh for helpful statistical input. Correspondence concerning this article should be addressed to Peter Mende-Siedlecki, Department of Psychological & Brain Sciences, University of Delaware, Wolf Hall, Newark, DE 19716, United States. Email: [email protected] Abstract Racial disparities in pain care may be linked to a perceptual source: perceivers see pain less readily on Black (versus white) faces. We conducted an internal meta-analysis (40 studies; N=6252) to assess the generalizability, robustness, and psychological bases of this phenomenon. Meta-analysis strongly confirmed race-based gaps in pain perception and treatment. Moreover, bias in perception consistently facilitated bias in treatment. These effects were robust to differences in stimuli, samples, and perceiver gender and race. Notably, both Black and white perceivers showed a tendency to see pain less readily on Black faces, suggesting this bias is not merely a consequence of group membership. Further, increased dehumanization of and decreased intergroup contact with Black individuals was associated with racial bias in pain perception and treatment, though these effects were small. These results demonstrate the robustness of perceptual contributions to racial pain disparities and shed light on potential targets for future intervention. Word count: 149/150 Keywords: social perception, racial disparities, pain, meta-analysis, individual differences What factors fuel racial bias in pain perception and treatment?: A meta-analysis across 40 experimental studies Pain experienced by Black patients is systematically under-diagnosed and undertreated (Anderson, Green, & Payne, 2009; Green et al., 2003; Lee et al., 2019). This disparity exists across virtually all types of pain (Green et al., 2003), care settings (Mossey, 2011), and age ranges (Goyal et al., 2020; Lavin & Park, 2012). As unrelieved pain has negative consequences for overall quality of life (Katz, 2002; Niv & Kreitler, 2001) and health (Wells, Pasero, & McCaffery, 2008), researchers must fully scrutinize the foundations of disparities in pain care. Several decades of research have focused on the psychological processes underpinning racial disparities in healthcare (e.g., Dovidio et al. 2008; Penner, Blair, Albrecht, & Dovidio, 2014). Pain care disparities in particular are linked to racial stereotypes regarding status or toughness (Trawalter, Hoffman, & Waytz, 2012; Deska et al., 2020), false beliefs about biological differences (Hoffman, Trawalter, Axt, & Oliver, 2016), implicit racial bias (Green et al., 2007; Sabin & Greenwald, 2012), and patient-provider racial concordance (Anderson, Gianola, Perry, & Losin, 2019). Moreover, an emerging literature demonstrates that gaps in pain care stem, in part, from biases in the visual perception of painful expressions (Mende-Siedlecki, Qu-Lee, Backer, & Van Bavel, 2019). However, the roots of this perceptual bias are still coming into focus. Here, we capitalized on the considerable amount of data on racial bias in pain perception (Drain, Goharzad, Qu-Lee, Lin, & Mende-Siedlecki, 2020; Mende-Siedlecki et al., 2019; 2020) to perform an internal meta-analysis examining the forces driving this phenomenon. Perceptual contributions to racial bias in pain care Painful expressions are associated with specific facial muscle movements—specifically, brow lowering, eyelid tightening, nose wrinkling, and raising of the upper lip and cheeks (Hill & Craig, 2002; Kunz, Meixner, & Lautenbacher, 2019). While pain recognition is robust and automatic (Simon, Craig, Gosselin, Belin, & Rainville, 2007), perceivers show more conservative thresholds for seeing pain on Black (versus white) faces, which facilitates a concordant bias in treatment recommendations (Mende-Siedlecki et al., 2019). This bias persists when equating stimuli in terms of contrast, luminance, hue, structure, and expression, and affects Black faces in particular: participants had essentially equivalent thresholds for perceiving pain in white and Asian faces (Mende-Siedlecki et al., 2019). This perceptual gap aligns with literature on human face processing. While “expert” (including same-race) face perception is configural (Rhodes, Hayward, & Winkler, 2006; Maurer, Le Grand, & Mondloch, 2002), in that perceivers attend to and encode second-order relations between parts of the face (e.g., spacing), other-race face processing is more featural (e.g., piecemeal) in nature (Rhodes et al., 2006, Hugenberg, Young, Bernstein, & Sacco, 2010). Notably, configural processing also supports recognition of emotional expressions (Bombari et al., 2013; Calder & Jansen, 2005), so we predicted it would play a critical role in racial bias in pain perception. To pinpoint this perceptual root, we presented Black and white faces in pain in upright and inverted orientations (Exps. 3-4, Mende-Siedlecki et al., 2019), since inversion interrupts configural processing. Racial bias in pain perception was reduced when faces were inverted: thresholds for pain on inverted white faces became more stringent. We concluded that differential sensitivity to pain on Black and white faces is associated with differential engagement of configural face processing. Subsequently, we explored the moderating effects of racial prototypicality (Drain et al., 2020), both in terms of bottom-up visual cues (racial phenotypicality; Maddox & Perry, 2017) and top-down category-level cues (stereotype associations between gender and race categories; Johnson, Freeman, & Pauker, 2012). Darker skintones impeded pain perception across race, while racially prototypic structure (e.g., Afrocentric structure on Black faces) exacerbated racial bias in pain perception. Next, we assessed the impact of overlapping stereotypes between race and gender categories (e.g., strong links between Black-male; weaker links between Black- female), which may influence emotion recognition (Stolier & Freeman, 2016). Indeed, race- based gaps in pain perception were strongest within male faces, consistent with research demonstrating that out-group male individuals may be more likely targets of discrimination than their female counterparts (Navarrete, McDonald, Molina, & Sidanius, 2010; Sidanius, Hudson, Davis, & Bergh, 2019). Thus, both bottom-up and top-down cues that are prototypic of Blackness may magnify race-based gaps in pain perception. Finally, we compared racial bias in pain perception against similar gaps in recognizing other expressions (Mende-Siedlecki et al., 2020)—specifically anger, happiness, fear, and sadness. While perceivers continued to demonstrate higher thresholds for seeing pain on Black faces, recognition of other emotions was not reliably affected by race. However, racial bias in pain perception was associated with blunted recognition of negative expressions on Black faces, in general. Overall, this bias was considerably more robust than other race-based gaps in emotion perception and had unique consequences for gaps in treatment recommendations. Despite consistency across investigations, we do not imply that perceptual bias is the primary basis of widespread and well-documented disparities in pain care. These disparities stem from a complex interplay of individual-level factors (e.g., implicit/explicit prejudice, perceptual bias, health- and pain-specific beliefs, communication-related processes, etc.) and overarching structural factors (Gee & Ford, 2011; Feagin & Bennefield, 2014), both of which have deep roots in the historical legacies of racism (Trawalter, Bart-Plange, & Hoffman, 2020). For example, historical medical practices founded on the false premise of biological differences between Black and white bodies are echoed in present-day beliefs (held by medical professionals) that Black people are less sensitive to pain (Hoffman et al., 2016). Other candidate mechanisms supporting racial bias in pain perception (e.g., dehumanization, contact) share a similar scaffolding. Contemporary dehumanization of Black individuals can be traced to historical representations used to justify slavery and deny rights to Black Americans (Goff, Eberhardt, Williams, & Jackson, 2008; Lott, 1999). Further, while increased intergroup contact may enhance configural processing of other-race faces (Hancock & Rhodes, 2008), real-world differences in contact stem directly from structural factors—segregation and discrimination