PNAS 2023 Vol. 120 No. 22 e2300995120 https://doi.org/10.1073/pnas.2300995120 1 of 12 All human social groups are human, but some are more human than others: A comprehensive investigation of the implicit association of “Human” to US racial/ethnic groups Kirsten N. Morehouse a , Keith Maddox b , and Mahzarin R. Banaji a,1 Contributed by Mahzarin R. Banaji; received January 17, 2023; accepted March 30, 2023; reviewed by Phillip A. Goff and Nour S. Kteily RESEARCH ARTICLE | PSYCHOLOGICAL AND COGNITIVE SCIENCES All human groups are equally human, but are they automatically represented as such? Harnessing data from 61,377 participants across 13 experiments (six primary and seven supplemental), a sharp dissociation between implicit and explicit measures emerged. Despite explicitly affirming the equal humanity of all racial/ethnic groups, White partic- ipants consistently associated Human (relative to Animal) more with White than Black, Hispanic, and Asian groups on Implicit Association Tests (IATs; experiments 1–4). This effect emerged across diverse representations of Animal that varied in valence ( pets , farm animals , wild animals , and vermin ; experiments 1–2). Non-White participants showed no such Human=Own Group bias (e.g., Black participants on a White–Black/Human– Animal IAT). However, when the test included two outgroups (e.g., Asian participants on a White–Black/Human–Animal IAT), non-White participants displayed Human=White associations. The overall effect was largely invariant across demographic variations in age, religion, and education but did vary by political ideology and gender, with self-identified conservatives and men displaying stronger Human=White associations (experiment 3). Using a variance decomposition method, experiment 4 showed that the Human=White effect cannot be attributed to valence alone; the semantic meaning of Human and Animal accounted for a unique proportion of variance. Similarly, the effect persisted even when Human was contrasted with positive attributes (e.g., God, Gods, and Dessert; experiment 5a). Experiments 5a-b clarified the primacy of Human=White rather than Animal=Black associations. Together, these experiments document a factually erroneous but robust Human=Own Group implicit stereotype among US White participants (and globally), with suggestive evidence of its presence in other socially dominant groups. implicit stereotypes | human–animal stereotypes | implicit association test | intergroup cognition | racial/ethnic stereotypes By all relevant biological criteria (e.g., ability to interbreed and produce viable offspring; refs. 1 and 2), all humans—regardless of group membership—belong to a single species. And yet, history provides ample evidence of cultural pseudospeciation (3)—the tendency to treat culturally manufactured social groups (e.g., based on religion, language, ethnicity) akin to distinct biological species. These perceptions are psychologically potent and can drive intergroup differentiation. For example, Leyens et al. (4, 5) and Kteily et al. (6) demonstrated that this differentiation shapes perceived capacity for secondary emotions (e.g., pride and guilt) and judgments of a group’s evolutionary progress, respectively. Haslam (7) further suggested that groups can be differentiated based on their possession of traits central to “human” nature (e.g., imaginative and ambitious) or traits that distinguish humans from other animals (e.g., analytical and artistic). As these examples illustrate, the field has not coalesced around a single definition of what it means to be more or less human (for a review, see ref. 8). However, data from these and related measures (e.g., mind attribution; ref. 9) converge to show that individuals tend to view three groups as more human: a) the self (e.g., refs. 10 and 11); b) ingroup members (e.g., refs. 12 and 13); and c) high-status groups (e.g., high-SES; ref. 14). Related streams of research using more indirect methods (e.g., reverse correlation and fMRI; refs. 15–18) have similarly documented differences in affording the quality human to all human groups (for a review, see ref. 8). For instance, using a Go/No-Go association task (19), Saminaden et al. (20) observed a tendency to associate “Modern people” more with Human and “Traditional people” more with Animal; and using an Implicit Association Test (IAT; ref. 21), Bernard et al. (22) observed an implicit thin–human/obese–animal ste- reotype. The existence of such associations may be consequential, as Goff and colleagues (23) demonstrated; participants with stronger implicit associations between Black Americans Significance All humans belong to the species Homo sapiens . Yet, throughout history, humans have breathed life into the Orwellian adage that “All [humans] are equal, but some [humans] are more equal than others.” Here, participants staunchly rejected this adage, with the overwhelming majority of over 61,000 participants reporting that all humans are equally human. However, across 13 experiments, US White participants (and White participants abroad) showed robust evidence of an implicit Human=Own Group association. Conversely, Black, Latinx, and Asian participants in the United States did not demonstrate this bias. These results highlight the tendency among socially dominant groups to reserve the quality Human for their own kind, producing, even in the 21st century, the age-old error of pseudospeciation. Author affiliations: a Department of Psychology, Harvard University, Cambridge, MA 02138; and b Department of Psychology, Tufts University, Medford, MA 02155 Author contributions: K.N.M., K.M., and M.R.B. designed research; K.N.M. and M.R.B. performed research; and K.N.M., K.M., and M.R.B. wrote the paper. Reviewers: P.A.G., Yale University; and N.S.K., Northwestern University. The authors declare no competing interest. Copyright © 2023 the Author(s). Published by PNAS. This article is distributed under Creative Commons Attribution-NonCommercial- NoDerivatives License 4.0 (CC BY-NC- ND). 1 To whom correspondence may be addressed. Email: mahzarin_banaji@harvard.edu. This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas. 2300995120/-/DCSupplemental. Published May 22, 2023. Downloaded from https://www.pnas.org by 37.5.254.4 on November 18, 2024 from IP address 37.5.254.4. 2 of 12 https://doi.org/10.1073/pnas.2300995120 pnas.org (versus White Americans) with nonhuman primates also more strongly endorsed violence against Black suspects. Taken together, research has demonstrated that the perceived humanity of social groups is not in line with biological or moral imperatives. Indeed, unlike judgments of preference, which are inherently subjective and equivocal, variability in the ascription of “human” to different social groups is a violation of a biological fact, making the existence of such stereotypes additionally noteworthy. Overview of the Present Report Building upon this work, we conducted thirteen experiments (including seven supplemental experiments; SI Appendix , Appendix 2) to investigate the presence and strength of human–animal implicit stereotypes toward prominent racial/ethnic groups in the United States. Specifically, harnessing data from 61,377 participants (67% American residents), we aimed to a) establish whether racial/ethnic human–animal stereotypes can be detected on measures of implicit cognition and whether they diverge or align with explicit cognition; b) determine whether these stereotypes, if they exist, are robust across various contrasts (e.g., White–Black, White–Latinx, and White–Asian) and demographic subgroups (e.g., White and non- White groups); and c) explore the mechanisms underlying these stereotypes to clarify the meaning of the obtained results (e.g., clarifying the role of semantics, beyond evaluations). Cultural pseudospeciation could theoretically occur across any socially manufactured category. We focused on race/ethnicity because individuals of European descent have been historically depicted as being more human (24–26). Further, race/ethnicity in the US context is sui generis given its multiethnic makeup, its relatively recent history of slavery, and explicit ascriptions of Black Americans as nonhuman (e.g., refs. 26–29). As such, participants’ stereotypes may refract these false beliefs or align with the fact that all racial/ethnic groups are equally human. IATs were used to capture the strength of associations between pairs of racial/ethnic groups (e.g., White–Black) and the attributes Human and Animal. In most studies, a contrastive attribute of Animal was selected because a predominant way in which humans have opted to express the belief that outgroups are less human is to liken them to nonhuman categories of animal, and much of the experimental research to date has adopted it. Here, to ensure that the emergence of any group stereotype was not limited to specific representations of Animal, the attribute was represented within and across experiments by diverse representations of Animal (e.g., pets, farm animals, wild animals, and vermin ) as well as generic terms like “beast” and “brute” ( SI Appendix , Appendix 2). In yet other experiments, we compared Human to attributes besides Animal, including suprahuman (e.g., God, Gods) and other highly positive (e.g., Dessert, Flower) attributes. Moreover, to determine the generality or specificity of these stereotypes, we examined whether human–animal stereotypes were confined to the White–Black contrast or reflected a more general tendency to associate certain groups (e.g., socially advantaged groups; ref. 14) with Human over Animal. Specifically, we meas- ured human–animal stereotypes toward four prominent racial/ ethnic groups that vary in their history and stereotype content within the US society: White, Black, Latinx, and Asian. In every test in the main text, White served as the comparison category. This provided the opportunity to explore whether implicit stere- otypes emerge in all three contrasts (i.e., White–Black, White– Hispanic, and White–Asian) or only in particular contrasts (e.g., in the White–Black contrast but not White–Asian). In addition to documenting the comparative strength of stere- otypes across contrasts (e.g., White–Black versus White–Asian), the use of large samples allowed for subgroup analyses that are typically incomputable. Perhaps most importantly, we tested whether this Human=Own Group association was expressed by all participants or only by members of advantaged racial/ethnic groups (e.g., White Americans). Further, robust samples permitted tests of the role of other demographic characteristics, besides race/eth- nicity, on human–animal stereotypes. For example, DeLuca-McLean and Castano (30) observed higher levels of infrahumanization (i.e., the denial of secondary emotions; ref. 5) among self-identified political conservatives, and Kteily et al. (6) observed a positive rela- tionship between social dominance orientation (SDO) and the tendency to characterize non-White groups as less evolved. Such variation, if also observed on implicit measures, may reveal features that predict the emergence of implicit human–animal stereotypes. As such, potential variability across age, gender, political ideology, education, and religion was additionally assessed. Finally, we explored two questions to probe the mechanisms underlying this effect. First, do implicit human–animal stereotypes measure anything beyond valence? That is, are “Human” and “Animal” merely proxies for “Good” and “Bad”, respectively, given the valence asymmetry of these terms? Or do any observed associa- tions reflect genuine engagement with the semantic meaning of these terms? Directly testing these competing interpretations has impor- tant implications for the construct validity of the test. Second, which pole of the IAT drives human–animal stereotypes? The relative nature of the IAT makes it challenging to determine whether Human=White associations, Animal=non-White associations, or both drive these stereotypes. However, we created operationalizations designed to disentangle these possibilities. Ultimately, an individual’s racial or ethnic membership has no biologically defensible bearing on their degree of humanity. Accordingly, if an implicit stereotype tying Human more to one racial/ethnic group exists, then it is critical to document this deviation from accuracy, as denials of humanity have been associated with reduced altruism (31, 32) and empathy (33), increased aggression (34, 35), support for punitive policies (6), and greater acceptance of violence (23, 36). Experiments 1-2 As an initial point of departure, experiments 1-2 examined whether White and Black groups were equally and automatically associated with the attributes Human and Animal. These two groups were selected because of their unique position in US history and contemporary society. Black Americans have been depicted as less than human in media (e.g., refs. 26–29), and many were explicitly designated as such by the 1787 Three-Fifths compro- mise. Importantly, extending work by Goff et al. (37), the present experiments tested the association of White and Black with the more basic attributes Human and Animal. Although a plenary representation of Human can be created with clear exemplars (e.g., man, woman, human, and person ), nonhuman animals vary greatly across dimensions (e.g., valence and traits) that may influence the default mental representation of the term Animal. To represent multiple meanings of the term and therefore allow maximal generalization, four conceptualiza- tions of Animal were created: pets , farm animals, wild animals, and vermin. On the one hand, associations between Animal and the social groups White and Black may vary according to the instantiation of Animal, suggesting that only specific representa- tions of Animal discriminate between social groups. On the other hand, if all instantiations of the attribute Animal (e.g., pets and vermin) produce similar effects, then the conclusion that a core concept of Animal is involved can be more confi- dently drawn. Downloaded from https://www.pnas.org by 37.5.254.4 on November 18, 2024 from IP address 37.5.254.4. PNAS 2023 Vol. 120 No. 22 e2300995120 https://doi.org/10.1073/pnas.2300995120 3 of 12 Moreover, given that the data were collected in the months following George Floyd’s murder, we administered an exploratory set of items about police violence and engagement in antiracism activities. These items are reported in SI Appendix , Appendix 3. Results and Discussion Explicit Attitudes. On a 1 to 10 scale, participants reported feeling “somewhat” warm toward both White people (M = 6.95, SD = 2.10) and Black people ( M = 7.56, SD = 1.95), with greater warmth reported toward Black than White people, t (846) = 8.93, P < 0.0001, Cohen’s d = 0.31, 95% CI [0.24, 0.38]. This was true among both White participants ( t (591) = 4.90, P < 0.0001, Cohen’s d = 0.20, 95% CI [0.12, 0.28]) and non-White participants ( t (240) = 8.16, P < 0.0001, Cohen’s d = 0.53, 95% CI [0.39, 0.66]). * Explicit Stereotypes. Participants clearly affirmed the humanity of both groups, associating Black ( M = 1.63, SD = 1.15) and White ( M = 1.78; SD = 1.29) targets with Human more than Animal. † In fact, less than 4% of participants reported that they considered either group to be more Animal than Human. Overall, the data suggest that, at least explicitly, participants affirmed the humanity of both groups. Implicit Stereotypes. The critical result from experiments 1–2 is that implicit associations diverged both from biological fact and from participants’ self-reported beliefs. On all four IATs, Human was more associated with White, and Animal was more associated with Black (all IAT Ds > 0.17). Despite considerable heterogeneity that was intentionally intro - duced to create diverse representations of the Animal attribute (e.g., varying in valence and trait attributions; ref. 38), one- sample t-tests indicated that this White–Human/Black–Animal (hereafter “Human=White”) association differed significantly from zero in all four animal conditions (all ps < 0.0001, all Cohen’s d > 0.40). The strength of association was statistically indistinguishable when the attribute Animal was represented by highly negative “vermin” or by more positive “pets,” t (22360) = 0.02, P = 0.988, Cohen’s d = 0.00, 95% CI [−0.04, 0.06]. In addition, a supplemental experiment ( N = 2,912) demonstrated that this effect persisted when exemplars such as beast and brute served as the attribute stimuli ( SI Appendix , Appendix 2, experiment S1). This evidence of a generalized association between Black with Animal (and White with Human) is not in conflict with Goff et al.’s (37) find- ing that Black Americans are relatively more associated with Apes and White Americans are relatively more associated with Big Cats. The same group can simultaneously be more associated with the high- level representation of Animal, relative to Human, and more associated with a specific class of animals (e.g., nonhuman pri- mates), relative to another (e.g., big cats). Effect of participant racial group on implicit stereotypes. Partici- pants’ self- reported race/ethnicity reliably predicted implicit human–animal stereotypes (see Table 1 for condition- specific means across experiments). As visualized in Fig. 1, White participants displayed an implicit Human=White association in all four animal conditions, IAT D avg = 0.22, t (7451) = 45.42, P < 0.0001, Cohen’s d = 0.53, 95% CI [0.50, 0.55]. By contrast, Black participants did not display a symmetric Human=Black effect. Instead, and aligning with their self-reported beliefs, Black participants more equally associated Human and Animal with their own group and White, IAT D avg = –0.06, t (590) = –3.59, P < 0.0001, Cohen’s d = –0.15, 95% CI [–0.23, –0.07]. Interestingly, when the IAT captured stereotypes toward two out- groups (e.g., Asian participants taking a White–Black/Human– Animal IAT), participants (hereafter “third-party participants”) did not associate Human with both outgroups equally. Instead, third-party participants assigned the attribute Human more to the socially advan- taged group (White) and Animal more to the socially disadvantaged group (Black) in every condition (Table 1). In fact, the Human=White association was only “slightly” stronger among White participants than among third-party participants, IAT D avg = 0.17, t (3021) = 22.2, P < 0.0001, Cohen’s d = 0.41, 95% CI [0.37, 0.44]. Taken together, three results from experiments 1-2 are note- worthy. First, a sharp dissociation between explicit and implicit measures emerged. Despite overwhelming recognition of the humanity of Black and White social groups, White participants displayed a pervasive implicit Human=White association. Indeed, this factually inaccurate stereotype emerged when Animal was represented in multiple ways, from amiable pets to vermin. Second, only White participants displayed the Human=Own Group effect. Black participants’ associations more closely aligned with the biological and moral imperative that all racial/ethnic groups are equally human. Third and finally, third-party partici- pants (e.g., Asian and Latinx participants taking a White–Black/ Human–Animal IAT) demonstrated greater automatic ascription of humanity to White than to Black. This finding demonstrates the pervasive power of group status in shaping the minds of mem- bers of more and less advantaged groups alike. Experiment 3 Despite recognizing the humanity of both Black and White groups on self-report measures, White and third-party participants con- sistently displayed an implicit Human=White association (exper- iments 1–2). Are these results specific to the White–Black comparison? Or do they reflect a general tendency to ascribe Human more to White and Animal more to non-White groups? To test this, experiment 3 compared White not only to Black (providing a replication of experiments 1–2) but also to Latinx and Asian. These groups were selected because they are all prom- inent racial/ethnic groups in the United States but vary in their cultural histories and trait attributions. For instance, Black Americans are stereotyped as threatening, lazy, and poor (e.g., refs. 39 and 40). By contrast, Asian Americans are considered a model minority and are stereotyped as intelligent but shy (e.g., refs. 41 and 42). Thus, even if implicit human–animal stereotypes exist, they may emerge only in specific contrasts (e.g., White– Black). Further, to assess the extent to which this stereotype was widely shared, variability across six demographic characteristics— race/ethnicity, gender, political ideology, age, education, and reli- gion—was newly examined. Results and Discussion Explicit Attitudes and Stereotypes. Explicit attitudes. Replicating experiment 1, participants reported feeling at least slightly warm (all means > 6) toward White, Black, * This explicit expression of greater warmth towards Black Americans (versus White Americans) by White Americans is a relatively new result. Previous data collections from the same source (e.g., ref. 45) routinely showed a small but reliable own group preference in White Americans. Future research will determine whether this shift is a permanent or a function of the post-Floyd timing of the data collection. † Participants affirmed the humanity of Black groups to a slightly stronger degree than White groups, t (825) = 4.77, P < 0.001, Cohen’s d = 0.17, 95% CI [0.10, 0.23]. Pairwise comparisons indicated that this effect was driven by non-White participants, who more strongly associated Black people (versus White people) with “Human” (over “Animal”), t (230) = 5.01, P < 0.0001, Cohen’s d = 0.33, 95% CI [0.20, 0.46]. White participants explicitly associated Black and White people with “Human” (over “Animal”) to a similar degree, t (580) = 1.81, P = 0.072, Cohen’s d = 0.07, 95% CI [−0.01, 0.16]. Downloaded from https://www.pnas.org by 37.5.254.4 on November 18, 2024 from IP address 37.5.254.4. 4 of 12 https://doi.org/10.1073/pnas.2300995120 pnas.org Table 1. Overview of IAT Conditions and Effects Experiment [condition] Category labels (Category stimuli) Attribute labels (Attribute stimuli) Overall IAT D-score IAT D-score across demographics Experiments 1–2 [ Pets ] Black (faces: set 1) White (faces: set 1) Human ( human, person, man, woman ) Animal ( dogcat, hamster, gerbil ) 0.17 95% CI [0.157, 0.189] White: 0.21 ( n = 1793) Third- Party: 0.15 ( n = 776) Black: −0.07( n = 155) Experiments 1–2 [ Farm ] Black (see above) White (see above) Human (see above) Animal ( pigcow, horse, goat ) 0.19 [95% CI: 0.170, 0.201] White: 0.22 ( n = 1938) Third- Party: 0.16 ( n = 764) Black: −0.07 ( n = 145) Experiments 1–2 [ Vermin ] Black (see above) White (see above) Human (see above) Animal ( snakerat, cockroach, lizard ) 0.18 [95% CI: 0.159, 0.191] White: 0.19 ( n = 1887) Third- Party: 0.19 ( n = 702) Black: −0.08 ( n = 140) Experiments 1–2 [ Wild ] Black (see above) White (see above) Human (see above) Animal ( tigerhippo, rhino, bear ) 0.24 [95% CI: 0.220, 0.251] White: 0.27 ( n = 1834) Third- Party: 0.21 ( n = 780) Black : −0.03 ( n = 151) Experiment 3 [Black/White] Black (faces: set 1) White (faces: set 1) Human ( human, person, man, woman ) Animal ( bear, hippo, cow, horse ) 0.23 [95% CI: 0.218, 0.236] White: 0.27 ( n = 4114) Third- Party: 0.21 ( n = 2564) Black: −0.02 ( n = 500) Experiment 3 [Hispanic/White] Hispanic (names: set1) White (names: set 1) Human (see above) Animal (see above) 0.27 [95% CI: 0.264, 0.282] White: 0.33 ( n = 3888) Third- Party: 0.26 ( n = 1904) Latinx: 0.07 ( n = 849) Experiment 3 [Asian/White] Asian (faces: set 1) White (faces: set 1) Human (see above) Animal (see above) 0.26 [95% CI: 0.254, 0.273] White: 0.32 ( n = 3721) Third- Party: 0.21 ( n = 2564) Asian: 0.04 ( n = 326) Experiment 4 [Black/White] Black (faces: set 2) White (faces: set 2) Human (see above) Animal (see above) 0.19 [95% CI: 0.160, 0.212] White: 0.22 ( n = 628) Third- Party: 0.17 ( n = 218) Black: 0.01 ( n = 86) Experiment 4 [Hispanic/White] Hispanic (names: set1) White (names: set 1) Human (see above) Animal (see above) 0.27 [95% CI: 0.241, 0.293] White: 0.32 ( n = 519) Third- Party: 0.22 ( n = 167) Latinx: 0.05 ( n = 79) Experiment 4 [Asian/White] Asian (faces: set 2) White (faces: set 2) Human (see above) Animal (see above) 0.26 [95% CI: 0.236, 0.284] White: 0.28 ( n = 654) Third- Party: 0.22 ( n = 268) Asian : insufficient n ( n = 17) Experiment 5a [Human–God] Black (faces: set 2) White (faces: set 2) Human ( human, people, person, man, woman ) God ( god, almighty, divine, deity, creator ) 0.39 [95% CI: 0.343, 0.439] White: 0.39 ( n = 204) Experiment 5a [Human–Gods] Black (see above) White (see above) Human (see above) Gods ( gods, zeus, apollo, aphrodite, venus ) 0.49 [95% CI: 0.439, 0.539] White: 0.49 ( n = 190) Experiment 5a [Human–Flower] Black (see above) White (see above) Human (see above) Flower ( flower, rose, daffodil, tulip, daisy ) 0.13 [95% CI: 0.075, 0.190] White: 0.13 ( n = 203) Experiment 5a [Human–Dessert] Black (see above) White (see above) Human (see above) Dessert ( dessert, pie, cookie, cake, macaroon ) 0.19 [95% CI: 0.140, 0.246] White: 0.19 ( n = 211) Experiment 5a [Human–Clothing] Black (see above) White (see above) Human (see above) Clothing ( clothing, shoe, hat, sweater, jacket ) 0.12 [95% CI: 0.057, 0.179] White: 0.12 ( n = 196) Experiment 5a [Human–Furniture] Black (see above) White (see above) Human (see above) Furniture ( furniture, chair, table, sofa, desk ) 0.17 [95% CI: 0.114, 0.226] White: 0.17 ( n = 190) Experiment 5a [Human–Appliance] Black (see above) White (see above) Human (see above) Appliance ( appliance, stove, fridge, toaster, freezer ) 0.19 [95% CI: 0.134, 0.244] White: 0.19 ( n = 199) Experiment 5a [Human–Robot] Black (see above) White (see above) Human (see above) Robot ( robot, bot, machine, automaton, droid ) 0.39 [95% CI: 0.336, 0.451] White: 0.39 ( n = 183) Experiment 5b [Animal–Death] Black (see above) White (see above) Animal ( animal, beast, brute, animalistic, creature ) Death ( dead, dying, casket, graveyard, tombstone ) −0.27 [95% CI: −0.318, −0.229] White: -0.27 ( n = 220) Experiment 5b [Animal–Ghost] Black (see above) White (see above) Animal (see above) Ghost ( ghost, ghoul, spirit, phantom, haunted ) −0.03 [95% CI: −0.090, 0.029] White: -0.03 ( n = 187) Experiment 5b [Animal–Toxin] Black (see above) White (see above) Animal (see above) Toxin ( toxin, chemical, pesticide, pollution, acid ) 0.00 [95% CI: −0.049, 0.059] White: 0.00 ( n = 191) Experiment 5b [Animal–Disaster] Black (see above) White (see above) Animal (see above) Disaster ( disaster, flood, fire, hurricane, storm ) −0.04 [95% CI: −0.094, 0.014] White: -0.04 ( n = 207) Experiment 5b [Animal–Robot] Black (see above) White (see above) Animal (see above) Robot ( robot, bot, machine, automaton, droid ) −0.14 [95% CI: −0.196, −0.087] White: -0.14 ( n = 179) (Continued) Downloaded from https://www.pnas.org by 37.5.254.4 on November 18, 2024 from IP address 37.5.254.4. PNAS 2023 Vol. 120 No. 22 e2300995120 https://doi.org/10.1073/pnas.2300995120 5 of 12 Hispanic, and Asian groups. However, on the new measure of explicit preference, both White and non-White participants reported a relative preference for their own group, with group means ranging from 3.81 (White participants’ preference for White over Black) to 5.20 (Black participants’ preference for Black over White). Additional details are reported in SI Appendix , Appendix 3. Explicit stereotypes. Participants overwhelmingly affirmed the equal humanity of both groups. In fact, over 88% of non-White participants and over 96% of White participants endorsed the equal humanity of both groups. ‡ In the minority (<7%) of cases where equal humanity was not affirmed, participants asserted a social correction by rating Black, Asian, and Hispanic groups as more human than White groups. Implicit Stereotypes. The primary aim of experiment 3 was to explore whether the implicit Human=White associations observed in experiments 1-2 were a) specific to the White–Black contrast or b) reflect a more general tendency to associate Human more with White and Animal more with non-White groups. Replicating the results of experiments 1-2, White (IAT D = 0.27, t (4114) = 43.4, P < 0.0001, Cohen’s d = 0.68, 95% CI [0.64, 0.71]) and third-party test takers (IAT D = 0.20, t (2563) = 26.0, P < 0.0001, Cohen’s d = 0.51, 95% CI [0.47, 0. 55]) displayed an implicit Human=White association in the White–Black IAT condition, while Black participants displayed relative accuracy (IAT D = −0.02, t (500) = -2.23, P = 0.253, Cohen’s d = −0.05, 95% CI [−0.14, 0.04]). Newly, and providing evidence of a general tendency to asso- ciate Human more with White, White participants displayed an implicit Human=White association in both the White–Hispanic contrast (IAT D = 0.33, t (3888) = 55.4, P < 0.0001, Cohen’s d = 0.89, 95% CI [0.78, 1.03]) and the White–Asian contrast (IAT D = 0.32, t (3720) = 51.6, P < 0.0001, Cohen’s d = 0.85, 95% CI [0.81, 0.88]). Similarly, third-party participants displayed an implicit Human=White association in both the White– Hispanic contrast (IAT D = 0.26, t (1903) = 30.4, P < 0.0001, Cohen’s d = 0.70, 95% CI [0.65, 0.75]) and the White–Asian contrast (IAT D = 0.21, t (2563) = 27.8, P < 0.0001, Cohen’s d = 0.55, 95% CI [0.52, 0.59]), but to a lesser degree than White participants (all p s < 0.005). Interestingly, unlike Black participants, when their own group served as the contrast to White on the IAT (e.g., Asian participants taking a White–Asian/Human–Animal IAT), Latinx and Asian par- ticipants did not assign Human to both groups equally. Instead, Latinx participants (IAT D = 0.07, t (848) = 5.23, P < 0.0001, Cohen’s d = 0.18, 95% CI [0.11, 0.25]) and Asian participants (IAT D = 0.04, t (325) = 2.02, P = 0.044, Cohen’s d = 0.11, 95% CI [0.003, 0.22]) displayed weak implicit Human=White associations. This pattern was replicated in the meta-analytic estimates ( SI Appendix , Appendix 4). Overall, these results provide evidence for the robustness of the Human=White association across racial/ethnic comparisons and the disconnect between stated beliefs and implicit associations. In SI Appendix , Appendixes 2 and 3, we probed the generality of human–animal stereotypes in two additional ways. First, we examined whether White participants’ Human=Own Group asso- ciations similarly emerged when Asian was represented as specific national/cultural (rather than racial/ethnic) entities. Providing evi- dence for the pervasiveness of human–animal stereotypes, White participants displayed implicit Human=Own Group associations when White was compared to groups identified as Chinese and Japanese ( N S5 = 10,045; Cohen’s d > 0.82; SI Appendix , Appendix 2). Similarly, White Americans implicitly associated Human more with (White) Americans than (White) Canadians ( N S6 = 875; Cohen’s d = 0.68; SI Appendix , Appendix 2); in fact, these Human=Own Group associations were just as strong as the effect in the White–Black contrast. These findings indicate that the results observed in experiments 1–3 were not specific to White versus non-White contrasts. Instead, they suggest a more general tendency for advantaged groups to associate their own group more with Human, regardless of whether the ingroup is demarcated by race, ethnicity, or nationality. Second, we assessed whether this Human=White effect is unique to White Americans or emerges in White participants globally. Providing evidence for the generality of this stereotype across indi- viduals who identify as White, non-US White participants consist- ently displayed Human=White associations, irrespective of country or geographic region of residence ( SI Appendix , Appendix 3). Nevertheless, a related question remains: Is this Human=Own Group effect a signature of White participants, specifically, or of dominant groups in any society? We conducted a preliminary analysis of a dominant non-White group and find initial evidence that East Asians living in East Asia display an implicit Human=Own Group effect (In SI Appendix , Appendix 3). In other words, this effect may not be unique to White Americans or even White participants globally; instead, the effect may reflect the automatic association of Human to Own Group in any socially dominant group in a society, culture, or region. However, this test was an exploratory analysis that requires further confirmation in planned experiments. Taken together, these data indicate that White participants display a pervasive, factually incorrect, implicit Human=Own Group stere- otype. Moreover, they suggest that this stereotype a) extends beyond the White–Black comparison to other racial/ethnic and even national group comparisons and b) is not limited to Americans who identify as White. Indeed, this initial evidence suggests that a Human=White association emerges globally in those who identify as White. Demographic moderators. This consistency across target category contrasts is noteworthy, but is the effect similarly invariant across T able 1. Overview of IAT Conditions and Effects (Continued) Experiment [condition] Category labels (Category stimuli) Attribute labels (Attribute stimuli) Overall IAT D-score IAT D-score across demographics Experiment 5b [Animal–Appliance] Black (see above) White (see above) Animal (see above) Appliance ( appliance, stove, fridge, toaster, freezer ) 0.09 [95% CI: 0.037, 0.136] White: 0.09 ( n = 211) Experiment 5b [Animal–Furniture] Black (see above) White (see above) Animal (see above) Furniture ( furniture, chair, table, sofa, desk ) 0.10 [95% CI: 0.041, 0.149] White: 0.10 ( n = 192) Experiment 5b [Animal–Clothing] Black (see above) White (see above) Animal (see above) Clothing ( clothing, shoe, hat, sweater, jacket ) 0.10 [95% CI: 0.053, 0.154] White: 0.10 ( n = 207) Positive IAT D-scores indicate either implicit White–Human/Black–Animal (experiments 1–4), White–Human/Black–[OTHER] associations (experiment 5a), or Animal–Black/White–[OTHER] (experiment 5b) associations. ‡ >96% of White participants reported that White and [Black][Hispanic][Asian people are equally human. 90% of third-party participants reported that each pair was equally human. 81% of Black participants reported that White and Black people are equally human. >85% of Asian and Latinx participants reported that White and Asian or White and Hispanic people, respectively, are equally human. Downloaded from https://www.pnas.org by 37.5.254.4 on November 18, 2024 from IP address 37.5.254.4. 6 of 12 https://doi.org/10.1073/pnas.2300995120 pnas.org participant gender, age, level of education, political ideology, and religion? In other words, are these stereotypes observed across demographic subgroups or driven by particular demographic subgroups (e.g., older participants)? Analyses revealed that education and religion did not moderate the strength of implicit Human=White associations in any of the three racial/ethnic contrasts (White–Black, White–Hispanic, White–Asian). Given the statistical power of these analyses, we can confidently assume that these null effects were not type II errors. Participant age was a significant predictor of stereotype strength only in certain contrasts. § Specifically, in the White– Hispanic and White–Asian contrasts (but not in the White–Black contrast), older participants (>40 y old at the time of testing) displayed stronger implicit Human=White associations than younger participants (<20 y old at the time of testing). By contrast, gender and political ideology emerged as significant moderators of the effect,** with men and self-identified conservatives express- ing slightly stronger implicit Human=White associations than women and self- identified liberals, respectively (Table 2). A similar pattern was observed for explicit stereotypes. Specifically, age, religion, and education did not moderate the strength of explicit stereotypes in the White–Hispanic or White–Asian contrasts. Age and education were related to explicit stereotypes only in the White– Black contrast, with younger and college-educated participants recording higher rates of explicit Human=Black stereotypes. As with implicit stereotypes, gender and political ideology emerged as sig- nificant moderators of the effect in every contrast (Table 2). Experiment 4 Having demonstrated the robustness and generality of the Human= White effect, experiment 4 served to clarify the mechanisms under- lying the effect. Specifically, experiment 4 examined whether implicit human–animal stereotypes capture anything beyond gen - eralized valence or attitudes. That is, given the evaluative asymme- try of the attributes, with Human being more evaluatively positive in this context than Animal ( N S7 = 491; Cohen’s d = 1.02; SI Appendix , Appendix 2), an association between Human and White may largely reflect valence consistency rather than a seman- tic association. Past work has attempted to eliminate a valence confound by selecting attribute stimuli that have been equated for valence (43) or by demonstrating that these associations are not moderated by participants’ implicit preferences (37). Here, to provide a direct test of the latter, we implemented a valence decomposition tech- nique introduced by Kurdi et al. (44). This technique requires each participant to complete two measures: an implicit stereotype IAT (e.g., White–Black/Human–Animal IAT) and an implicit attitude IAT (e.g., White–Black/Good–Bad IAT). Crucially, the analysis quantifies the variance left unexplained by a) implicit attitudes and b) measurement error. If the variance left unexplained is sta- tistically distinguishable from zero, then the implicit Human=White stereotype effect can be said to be conceptually unique from an implicit attitude. Results and Discussion Replicating the results of experiment 3, implicit Human=White associations were again observed in every race contrast (all IAT Ds > 0.18). Further, and in line with the well-established race attitude effect (e.g., refs. (45–47)), participants overall displayed an implicit preference for White, relative to Black (IAT D = 0.26), Hispanic (IAT D = 0.26), and Asian (IAT D = 0.20). Additionally, the correlations between implicit stereotypes (Human–Animal IATs) and implicit attitudes (Good–Bad IATs) were positive in all three racial/ethnic comparison: White–Black IAT ( r = 0.43), White–Hispanic IAT ( r = 0.31), and White–Asian IAT ( r = 0.28). In fact, the correlations in the White–Black contrast approached the maximally expected correlations, given the IAT’s test–retest reliability of roughly r = 0.56 (48). This initial result suggests that, as expected, implicit human–ani- mal stereotypes detect an evaluative component, making a variance decomposition analysis necessary. In all cases, the 95% bootstrap confidence interval for residual true variance (RTV) did not include zero (see Table 3 for the full variance decomposition output). These data suggest that implicit Human=White associations are not fully reducible to valence alone. Instead, the Human–Animal IATs do detect a semantic association between Human with White (and Animal with non-White), independently of valence. Fig. 1. Implicit White-Black/Human-Animal Stereotypes Across Group Membership, by Experiment. Positive IAT D-scores indicate an implicit White-Human/ Black-Animal association, and negative IAT D-scores indicate an implicit Black-Human/White-Animal association. Condition-specific estimates with fewer than 20 participants were not visualized. Error bars represent 95% confidence intervals around the mean estimate. Third-party participants are participants from racial/ethnic groups that are not invoked on the IAT. On the White-Bla