Living among people who vote the other way seems to make Americans less generous with something very personal: their blood. People whose political views sit far from the average in their state or commuting zone, or who feel like a political minority where they live, are less likely to donate, a large study finds. Racial diversity showed no comparable link.
The study is by Sung Eun Kim, a political scientist at Korea University, and Krzysztof Pelc, a professor of international relations at the University of Oxford. It was published online in Perspectives on Politics on March 21, 2024 (read the paper).
The authors set out to test a long-running idea from research on social capital: that ethnic diversity erodes trust and good deeds. They asked whether partisan diversity works the same way, using blood donation as a measure of selfless behaviour. The timing matters, they note, because the United States has been facing its worst blood shortage in over a decade.
A decade of survey data
The first analysis drew on the Cooperative Election Study, which covers more than 275,000 Americans from 2010 to 2020 and asks whether respondents gave blood in the past year. The share saying yes fell from 14% in 2010 to 9.5% in 2020.
For each person, the researchers measured how far their own ideology was from the average ideology of their state or commuting zone. They then compared donation rates, holding constant state, race, education, age, gender, citizenship and access to health infrastructure.
The further someone’s politics were from their neighbours’, the less likely they were to donate. A one standard deviation increase in that distance was linked to a drop of nearly one percentage point in the probability of giving blood. That matters against a baseline in the low teens. Women in the data were 3.4 to 3.5 points less likely to donate than men, and the authors call the political effect comparable to gender.
Social diversity mattered much less. A one standard deviation rise in an area’s share of immigrants was tied to a drop of only 0.2 points, and the authors describe the evidence for that link as mixed. Racial diversity had no negative effect.
It is the feeling of being outnumbered
To get at why, the authors ran their own preregistered survey of 3,505 American adults in December 2021. Rather than use the loaded word “minority”, they asked people how common their political beliefs, and separately their racial identity, were in the region where they live.
Ideology by itself did not predict donation. What did was the sense of being out of step: each one-point rise on a 0 to 10 scale of feeling like a political minority came with a lower stated likelihood of giving blood. Feeling like a racial minority had no such effect, a null result that held when only white respondents were analysed.
The authors suggest the difference may come from social norms. Open animosity toward another race is far less acceptable in American life than animosity toward the other party, so partisan division may leak into everyday behaviour more freely.
Taken together, the effect amounts to roughly a 20% drop from the baseline odds of donation. The authors stress that the data are observational, so the findings “are not strictly causal, and should thus be interpreted with care.” In their framing, affective polarization taxes not just conversations across party lines but generosity toward strangers, at a time when the national blood supply is already short.
Study Details:
- Title: Does Political Diversity Inhibit Blood Donations?
- Authors: Sung Eun Kim, Krzysztof Pelc
- Journal: Perspectives on Politics
- Publication Date: March 21, 2024
- DOI: 10.1017/S1537592724000021