This study investigates whether people's opinions about public policy are primarily driven by self-interest or in-group preference. Using experimental methods, the research focuses on how age-based carve-outs influence responses to policies that might otherwise benefit similar groups.

The findings reveal clear self-interest effects for older Americans facing potential Medicare cuts and demonstrate this tendency with a hypothetical student debt relief program targeting young people who are too old to qualify.

These results provide crucial insights by distinguishing genuine self-interest from affinity bias. The variation in these policy attitude responses offers empirical support specific to existing theories.