Abstract We tested whether people engage in proportional thinking when comparing the value of the lives of people in different countries, specifically, whether people consider a certain number of lost lives in a smaller country to be equivalent to the loss of a larger number of lives in a country with a larger population. We found evidence for this form of proportional thinking in Study 1, and in Studies 2–3 we further observed that it is modulated by motivated reasoning: In Study 2, there was more proportional thinking when it benefited the ingroup (1 ingroup life equals 4 outgroup lives) than when it benefited the outgroup (1 outgroup life equals 4 ingroup lives). In Study 3, there was more proportional thinking when it benefited the victim in a war (1 victim life equals 4 aggressor lives) than when both countries were victims. Study 3 also showed that this form of proportional thinking is more prevalent when thinking about collectives (1,000 lives in the smaller country are equivalent to 4,000 lives in the larger country) versus individuals (1 life in the smaller country is equivalent to 4 lives in the larger country).
Mata et al. (Thu,) studied this question.