Weight-based discrimination in financial reward and punishment decision making: causal evidence using a novel experimental paradigm

BACKGROUND/OBJECTIVES: Cross-sectional research has demonstrated weight-related stigma and discrimination, however experimental research providing causal evidence of financial-based weight discrimination is lacking. The aim of these preregistered experiments was to examine whether a novel paradigm in which participants attributed financial rewards and punishments could be used to detect weight bias. SUBJECTS/METHODS: One-hundred and twenty-one individuals participated in experiment 1 and one-hundred and sixty-six individuals participated in experiment 2. Both studies were conducted online, and participants were provided with biographies of hypothetical individuals in which weight-status was manipulated (normal weight vs. overweight/obesity) before being asked to provide rewards and punishments on their cognitive performance. In experiment 1 (within-participants design) participants observed one individual they believed to be normal weight and one individual they believed to be overweight/have obesity. In experiment 2 (between-participants design) participants observed one individual whilst also being provided with information about food addiction (Food addiction is real + individual with overweight/obesity vs. food addiction is a myth + individual with overweight/obesity vs control + individual with normal weight). RESULTS: In experiment 1, participants punished individuals who were described as having overweight/obesity to a greater extent to individuals who were normal weight (Hedge’s g = −0.21 [95% CI: −0.02 to −0.41], p = 0.026), but there was no effect on rewards. They were also less likely to recommend individuals with overweight/obesity to pass the tasks (X(2)(1) = 10.05, p = 0.002). In experiment 2, participants rewarded individuals whom they believed were overweight/obese to a lesser extent than normal-weight individuals (g = 0.49 [95% CI: 0.16 to 0.83]. There was no effect on punishment, nor any impact of information regarding food addiction as real vs a myth. CONCLUSION: Using a novel discrimination task, these two experiments demonstrate causal evidence of weight-based discrimination in financial decision making.