Spatial skills mediate gender differences in arithmetic strategy use despite comparable arithmetic accuracy.

Gender disparities in math-intensive STEM fields can be traced back to early childhood. The current study examined a potential factor through which these disparities may emerge: gender differences in arithmetic strategy use. In a sample of 80 U.S. second- and third-graders, we found that gender differences in arithmetic strategy use appear even when girls and boys demonstrate comparable arithmetic accuracy. Specifically, girls used counting strategies about 30 percentage points more often than boys, whereas boys relied more on transformation strategies (i.e., mentally transform a arithmetic problems into other problem(s)). Interestingly, when arithmetic problems were less familiar (i.e., missing-term problems), girls and boys both increased their use of transformation strategies, indicating that transformation strategies are accessible to girls. Further, gender differences in spatial skills partially mediated gender differences in the use of transformation strategies. Together, these findings suggest that girls' lower spatial skills may make using transformation strategies more cognitively demanding, leading girls to preferentially rely on counting strategies, particularly when solving familiar problems. The current study advances understanding of the mechanisms underlying early gender disparities in mathematics and suggests that early strategy differences may cascade into larger gaps over time.