About the Authors

Catrin Rode

crode@uoregon.edu

Affiliation Department of Psychology, University of Oregon, Eugene, Oregon, United States of America

Robby Robson

Affiliation Eduworks, Corvallis, Oregon, United States of America

Andy Purviance

Affiliation Eduworks, Corvallis, Oregon, United States of America

David C. Geary

Affiliation Psychological Sciences, University of Missouri, Columbia, Missouri, United States of America

Ulrich Mayr

Affiliation Department of Psychology, University of Oregon, Eugene, Oregon, United States of America

Competing Interests

RR & AP are employees of Eduworks. There are no patents, products in development or marketed products to declare. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.

Author Contributions

Conceived and designed the experiments: CR RR UM. Performed the experiments: CR. Analyzed the data: UM. Contributed reagents/materials/analysis tools: CR UM RR AP DG. Wrote the paper: CR UM DG.