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. 2016 Jul 5;113(27):7475-80.
doi: 10.1073/pnas.1524268113. Epub 2016 Jun 20.

The base rate principle and the fairness principle in social judgment

Jack Cao  1 , Mahzarin R Banaji  2
Affiliations

The base rate principle and the fairness principle in social judgment

Jack Cao et al. Proc Natl Acad Sci U S A. .

Abstract

Meet Jonathan and Elizabeth. One person is a doctor and the other is a nurse. Who is the doctor? When nothing else is known, the base rate principle favors Jonathan to be the doctor and the fairness principle favors both individuals equally. However, when individuating facts reveal who is actually the doctor, base rates and fairness become irrelevant, as the facts make the correct answer clear. In three experiments, explicit and implicit beliefs were measured before and after individuating facts were learned. These facts were either stereotypic (e.g., Jonathan is the doctor, Elizabeth is the nurse) or counterstereotypic (e.g., Elizabeth is the doctor, Jonathan is the nurse). Results showed that before individuating facts were learned, explicit beliefs followed the fairness principle, whereas implicit beliefs followed the base rate principle. After individuating facts were learned, explicit beliefs correctly aligned with stereotypic and counterstereotypic facts. Implicit beliefs, however, were immune to counterstereotypic facts and continued to follow the base rate principle. Having established the robustness and generality of these results, a fourth experiment verified that gender stereotypes played a causal role: when both individuals were male, explicit and implicit beliefs alike correctly converged with individuating facts. Taken together, these experiments demonstrate that explicit beliefs uphold fairness and incorporate obvious and relevant facts, but implicit beliefs uphold base rates and appear relatively impervious to counterstereotypic facts.

Keywords: Implicit Association Test; base rates; fairness; social cognition; stereotypes.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. S1.
Fig. S1.
Exp. 1 (N = 574): Distributions of explicit and implicit beliefs before facts about Jonathan and Elizabeth’s professions were learned. The dashed vertical lines indicate beliefs consistent with the fairness principle. Negative values indicate beliefs consistent with the base rate principle.
Fig. S2.
Fig. S2.
Exp. 1 (N = 574): Mean explicit beliefs about Jonathan and Elizabeth’s professions. Choices on the Likert-type scale are on the y axis. Error bars are 95% CIs.
Fig. 1.
Fig. 1.
Exp. 1 (N = 574): Mean implicit beliefs about Jonathan and Elizabeth’s professions. IAT D Scores are on the y axis. Error bars are 95% CIs.
Fig. 2.
Fig. 2.
Exp. 1: Mean implicit beliefs about Jonathan and Elizabeth’s professions only among participants whose implicit beliefs before learning the facts were neutral (N = 81). IAT D scores are on the y axis. Error bars are 95% CIs.
Fig. S3.
Fig. S3.
Exp. 2 (N = 808): Distributions of explicit and implicit beliefs before facts about Richard and Jennifer’s professions were learned. The dashed vertical lines indicate beliefs consistent with the fairness principle. Negative values indicate beliefs consistent with the base rate principle.
Fig. S4.
Fig. S4.
Exp. 2 (N = 808): Mean explicit beliefs about Richard and Jennifer’s professions. Choices on the Likert-type scale are on the y axis. Error bars are 95% CIs.
Fig. S5.
Fig. S5.
Exp. 2 (N = 808): Mean implicit beliefs about Richard and Jennifer’s professions. IAT D scores are on the y axis. Error bars are 95% CIs.
Fig. S6.
Fig. S6.
Exp. 2: Mean implicit beliefs about Richard and Jennifer’s professions among only participants whose implicit beliefs before learning the facts were neutral (N = 172). IAT D scores are on the y axis. Error bars are 95% CIs.
Fig. S7.
Fig. S7.
Exp. 3 (N = 659): Distributions of explicit and implicit beliefs before facts about Lapper and Affina’s professions were learned. The dashed vertical lines indicate beliefs consistent with the fairness principle. Negative values indicate beliefs consistent with the base rate principle.
Fig. S8.
Fig. S8.
Exp. 3 (N = 659): Mean explicit beliefs about Lapper and Affina’s professions. Choices on the Likert-type scale are on the y axis. Error bars are 95% CIs.
Fig. S9.
Fig. S9.
Exp. 3 (N = 659): Mean implicit beliefs about Lapper and Affina’s professions. IAT D scores are on the y axis. Error bars are 95% CIs.
Fig. S10.
Fig. S10.
Exp. 3: Mean implicit beliefs about Lapper and Affina’s professions among only participants whose implicit beliefs before learning the facts were neutral (N = 143). IAT D scores are on the y axis. Error bars are 95% CIs.
Fig. S11.
Fig. S11.
Exp. 4 (N = 1,417): Distributions of explicit and implicit beliefs before facts about Matthew and Benjamin’s professions were learned.
Fig. S12.
Fig. S12.
Exp. 4 (N = 1,417): Mean explicit beliefs about Matthew and Benjamin’s professions. Choices on the Likert-type scale are on the y axis. Error bars are 95% CIs.
Fig. S13.
Fig. S13.
Exp. 4 (N = 1,417): Mean implicit beliefs about Matthew and Benjamin’s professions. IAT D scores are on the y axis. Error bars are 95% CIs.
Fig. 3.
Fig. 3.
Exp. 4: Mean implicit beliefs about Matthew and Benjamin’s professions only among participants whose implicit beliefs before learning the facts were neutral (N = 403). IAT D scores are on the y axis. Error bars are 95% CIs.
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References

    1. Kaiser Family Foundation 2015. Distribution of Physicians by Gender. Available at kff.org/other/state-indicator/physicians-by-gender. Accessed December 15, 2015.
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