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Children and adults often have difficulties comparing decimal magnitudes. Although individuals attempt to reconcile decimals with prior whole-number and fraction knowledge, conceptual and procedural differences between decimals and prior knowledge of whole numbers and fractions can lead to incorrect strategies. The dynamic strategy choice account has proposed that saliency, recency, prior knowledge, and other factors contribute to strategy use when reasoning about decimals. We experimentally tested this theory using a priming technique to manipulate the saliency of different strategies prior to completion of a decimal magnitude comparison task. We hypothesized that whole-number priming (practicing whole-number comparisons with feedback) would increase whole-number bias in decimal comparisons (treating decimals with more digits as larger in magnitude), whereas fraction priming would increase fraction bias (treating decimals with fewer digits as larger in magnitude). We also explored participants’ performance in decimal comparisons after being primed by decimal comparisons with feedback. Sixth to eighth graders (N = 149) and adults (N = 175) were randomly assigned to 1 of 4 priming conditions: whole-number, fraction, decimal, or a control (flanker) task. Participants first completed numerical magnitude comparisons according to their priming condition (or control task) with feedback, then all conditions completed decimal comparisons without feedback. In both children and adults, fraction priming significantly reduced whole-number bias compared with the control. Among children, fraction priming significantly increased fraction bias. Moreover, children’s performance in the control and whole-number-priming conditions was characterized by strong whole-number bias, but in the decimal-priming condition, relatively brief feedback substantially improved decimal comparison performance.

Elementary school students often lack a conceptual understanding of linear measurement, which is revealed by their poor performance when the object to be measured is not aligned with the start of the ruler. Instead of correctly counting the units that correspond to the object (e.g., inches or centimeters), children often use 1 of 2 incorrect strategies: reading off the number that corresponds to the end of the object (the least-mature, read-off strategy) and counting the hash marks that flank the object (a more mature, but still incorrect, hash-mark strategy). We hypothesized that shifting to a more mature linear measurement strategy would require the ability to inhibit less-mature prepotent responses, such as read-off and hash-mark responses. In the present study, we predicted that children with better inhibitory control would be more likely to improve in their linear measurement strategy use over one year. Participants (n ϭ 317) were in 1st through 3rd grades when they completed a linear measurement task that required measuring objects that were not aligned with the start of the ruler; they also completed an inhibitory control task and control measures (visuospatial working memory, arithmetic calculations, and number line estimation). One year later, they repeated the linear measurement task. Students with higher initial inhibitory control were more likely to adopt a more mature strategy over time. Moreover, inhibitory control was a significant predictor of strategy improvement over and above other cognitive measures, including visuospatial working memory and arithmetic calculation skill.

Despite some gains, women continue to be underrepresented in many science, technology, engineering, and math (STEM) fields. Using a national longitudinal dataset of 690 participants born in 1991, we tested whether spatial skills, measured in middle childhood, would help explain this gender gap. We modeled the relation between 4th‐grade spatial skills and STEM majors while simultaneously accounting for competing cognitive and motivational mechanisms. Strong spatial skills in 4th grade directly increased the likelihood of choosing STEM college majors, above and beyond math achievement and motivation, verbal achievement and motivation, and family background. Additionally, 4th‐grade spatial skills indirectly predicted STEM major choice via math achievement and motivation in the intervening years. Further, our findings suggest that gender differences in 4th‐grade spatial skills contribute to women's underrepresentation in STEM majors. Research Highlights Using a national longitudinal dataset, we found 4th‐grade spatial skills directly predicted STEM college major choice after accounting for multiple cognitive and motivational mechanisms. Strong spatial skills in 4th grade also elevated STEM major choice via enhanced math achievement and motivation in the intervening years. Gender differences in 4th‐grade spatial skills contributed to women's underrepresentation in STEM college majors.

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