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

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

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.  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 Methods

9.  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) Methods

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 2X larger 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