Does “humanization” of the preborn explain why conservatives (vs. liberals) oppose abortion?

• Examines potential explanations of left–right differences in abortion support.
• Tests whether preborn “humanization” explains right (vs. left) abortion opposition.
• Preborn humanization explained very little of right versus left differences.
• Findings are inconsistent with common arguments made by partisan groups.

Those on the political right (vs. left) generally oppose abortion, with preborn humanness frequently cited as the reason. We test whether differences in preborn humanness perceptions actually underpin left–right differences in abortion support. We examine two types of right-wing ideology in student and community samples, asking whether perceptions of preborn humanness (a) explain conservative (vs. liberal) opposition to abortion; or (b) exert a greater impact on abortion opposition among conservatives (vs. liberals). Without exception, perceptions of preborn humanness explained very little of right–left differences in abortion support, and the association between preborn humanness perceptions and abortion opposition was no stronger for those on the political right (vs. left). These findings suggest that left–right differences on this critical, election-relevant social attitude are not explained by beliefs about “humanness”, contrary to popular belief.