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 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/obese) 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/obese. In experiment 2 (between-participants design) participants observed one individual whilst also being provided with information about food addiction (Food addiction is real + overweight/obese individual vs. Food addiction is a myth + overweight/obese individual vs control + normal weight individual). Results: In experiment 1, individuals punished individuals whom they were informed were overweight/obese to a greater extent to individuals who were normal weight (Hedge’s g=-.21 [95% CI: -.02 to -.41], p = .026), but there was no effect on rewards. They were also less likely to recommend overweight/obese individuals to continue to earn more money (X2(1) = 10.05, p = .002). In experiment 2, individuals rewarded individuals whom they believed were overweight/obese to a lesser extent than normal weight individuals (g = .49 [95% CI: .16 to .83]. There was no effect on punishment, nor any impact of information regarding food addiction as real vs a myth. Conclusion: Across two experiments a novel discrimination task demonstrated causal evidence of weight-based discrimination in financial decision making.