Kurzban, Tooby & Cosmides: “Can race be erased?” PNAS 2001

1. Kurzban, Tooby & Cosmides: “Can race be erased?” PNAS 2001 • Question: does the simple act of categorizing individuals into two social groupspredispose humans to discriminate in favor of their in-group andagainst the out-group? • Studies have confirmed that this behavior is remarkablyeasy to elicit: people discriminate against out-groups even whenthey are assigned to groups temporarily and anonymously by anexperimenter who uses dimensions that are trivial. • Throughout human history, intergroup conflict has focused on categorization between us and them.

2. Kurzban, Tooby & Cosmides: “Can race be erased?” PNAS 2001 • Selection may have favored the cognitive machinery for automatic encoding of an individual’s sex and age, but the same process for race is unlikely to have evolved • Our typical ancestral individual would almost never encounter individuals genetically distinct enough to classify as a different “race” • Their hypothesis: coalition encoding is as fundamental as sex encoding and age encoding, and more fundamental than race encoding

3. Hypothesis: • Automatic and mandatory encoding of race is a byproduct of adaptations that evolved to detect coalitions & alliances • Hunter gatherer societies lived in bands and neighboring bands frequently came into contact with each other • Computational machinery designed to detect coalitions should be sensitive to two factors: • Patterns of coordinated action • Cues that predict an individual’s political allegiances

4. Predictions • #1: Race per se will not be encoded across all social contexts and with equal strength • #2: Shared visual appearance is not necessary for coalition encoding • #3: Arbitrary cues other than racial appearance can be endowed with the same properties as race sometimes has by linking them to coalition membership

5. Predictions (cont…) • #4: Strength of race encoding will diminish by creating a social context where • Race is no longer a valid cue to coalition • There are alternative cues that reliably indicate coalitional affiliation • #5: Sex will be encoded more strongly than race even in contexts where it is irrelevant to coalition and task • #6: Encoding of sex will not diminish coalition encoding even though sex will be encoded far more strongly than race

6. Methods • Approach: Memory confusion protocol: dimensions used in encoding will be revealed by dimensions along which mistakes are made • General prediction: subjects will treat the dimension coalition in a fashion parallel to sex, age, and especially race • Specific prediction: subjects will encode coalition incidentally as part of impression formation without having been instructed to do so

7. Methods • Memory confusion protocol • Asked to form impressions of individuals • See sequence of sentences paired with photos • Surprise recall task • Uses errors in recall to reveal whether subjects are categorizing target individuals into groups

8. Methods • Subjects were told that (i) they will be seeing a series of photographs of individuals, each of which is paired with a sentence uttered by the individual pictures; (ii) each pictured individual belongs to one of two rival basketball teams that had been in a fight during the previous season, and their sentences were uttered in the context of a group conversation; and (iii) their task is to form an impression of the target individual as they are viewed

9. Methods • There was be a statement from one individual of one team followed by a statement from an individual of the other team , back and forth, and so on. • Each subject viewed 24 such one-sentence back-and-forth statements, for 8.5 sec each. • Each statement was paired with a photo of the individual that made it (so each individual in a group made a total of 3 such statements)

10. Experiment 1 • Each speaker was a young man • Only way to identify coalition was through the content of what they said • 4 speakers in each coalition • Two Euro-American men • Two African-American men • With no other identifiers, race should be used for encoding

11. Experiment 2 • Identical to Experiment 1 • Only added difference was whether individuals wore yellow or gray jerseys • So now we have a visual coalitional cue (though a fairly innocuous one?)

12. Experiment 3 and 4 • Same as experiment as 1 and 2 • The African Americans were replaced by White Euro American women • Prediction that gender will be more salient here than race was in expts 1 and 2

13. Results – By Experiments • Expt 1 (no visual clues as to coalition) • More within-coalition than between-coalition errors • Effect of race 2Xlarger than effect of coalition • Expt 2 (yellow shirts vs grey jerseys) • Significant increase in coalitional effect size • Effect size of race reduced • Effect of coalition larger than of race

14. Results – By Experiments • Expt 3: (males & females, no visual coalition cues) • Effect size of sex very high • Effect of sex greater than effect of coalition or race • Effect size of coalition small • Expt 4(males & females + yellow vs gray jerseys) • Effect size of sex very high • Effect of sex greater than effect of coalition or race • But effect size of coalition remains large

17. Discussion – Predictions 1, 2, and 3 • 1: Race is not encoded equally across all social contexts • Effect size of race diminished in expt 2 compared to expt 1 • 2: Shared appearance ≠ coalition. Coalitional encoding without appearance possible • More within rather than between coalition errors in expt 1 • 3: Cues other than race can be substituted for coalitional membership • Effect of shirt color in expt 2 larger than in expt 1.

18. Discussion – Predictions 4, 5, and 6 • 4: Racial encoding decreases when it is no longer valid and there are better indicators of coalition • Effect size for race diminished in expt 2 compared to expt 1. • 5: Sex is encoded more strongly than race • Effect sizes for sex were very high for expts 3 and 5 • 6: Sex encoding does not affect coalitional encoding • Coalitional effect did not decrease from expt 1 to 3 and from 2 to 4