Reference. Schroeders, U., Wilhelm, O., & Olaru, G. (2016). The influence of item sampling on sex differences in knowledge tests. Intelligence, 58, 22–32. doi:10.1016/j.intell.2016.06.003 Abstract. Few topics in psychology have generated as much controversy as sex differences in intelligence. For fluid intelligence, researchers emphasize the high overlap between the ability distributions of males and females, whereas research on sex differences in declarative knowledge often uncovers a male advantage. However, on the level of knowledge domains, a more nuanced picture emerged: while females perform better in health-related topics (e.