Joshua R. de Leeuw

Assistant Professor of Cognitive Science

Josh de Leeuw received his PhD in Cognitive Science and Psychological and Brain Sciences from Indiana University in 2016. He received his BA from Vassar College in 2008, majoring in Cognitive Science.

Josh's research is focused on the development and application of Internet-based tools for the study of human cognition. He created the widely-used jsPsych experiment software for conducting behavioral experiments online. He uses these tools to study how people learn and represent new information. 

BA, Vassar College; PhD, Indiana University
At Vassar since 2016


Olmsted Hall of Biological Sc
Box 201

Research and Academic Interests

Research Software
Games as Research Tools
Computational Modeling

Departments and Programs

Selected Publications


de Leeuw, J. R., Gilbert, R. A., Petrov, N., & Luchterhandt, B. (2022). Simulating behavior to help researchers build experiments. Behavior Research Methods, 1-11, doi:

de Leeuw, J. R., Andrews, J., Barney, L., Bigler, M., Bruna, P. J., Chen, Y., ... & Zhang, L. (2021). Words May Jump-Start Meaning More Than Vision: A Non-Replication of Early ERP Effects in Boutonnet and Lupyan (2015). Collabra: Psychology, 7(1), 29763. doi:

Fyfe, E. R., de Leeuw, J. R., Carvalho, P. F., Goldstone, R. L., Sherman, J., Admiraal, D., ... & Motz, B. A. (2021). ManyClasses 1: Assessing the generalizable effect of immediate feedback versus delayed feedback across many college classes. Advances in Methods and Practices in Psychological Science, 4(3), doi:

de Leeuw, J., Andrews, J., Altman, Z., Andrews, R., Appleby, R., Bonnano, J., ... & Shriver, A. (2019). Similar event-related potentials to structural violations in music and language. Meta-Psychology3. doi: 10.15626/MP.2018.1481

Hartshorne, J. K., de Leeuw, J. R., Goodman, N. D., Jennings, M., & O’Donnell, T. J. (2019). A thousand studies for the price of one: Accelerating psychological science with Pushkin. Behavior Research Methods51(4), 1782-1803. doi: 10.3758/s13428-018-1155-z

de Leeuw, J. R., Andrews. J. K., Livingston, K. R., & Chin., B. M. (2016). The effects of categorization on perceptual judgment are robust across different assessment tasks. Collabra: Psychology2(1), 9. doi:10.1525/collabra.32

de Leeuw, J. R., & Motz, B. A. (2016). Psychophysics in a web browser? Comparing response times collected with JavaScript and Psychophysics Toolbox in a visual search task. Behavior Research Methods48(1), 1-12. doi:10.3758/s13428-015-0567-2

de Leeuw, J. R. (2015). jsPsych: A JavaScript library for creating behavioral experiments in a Web browser. Behavior Research Methods47(1), 1-12. doi:10.3758/s13428-014-0458-y

In the Media


Download images for non-commercial use, photo credit required.

Joshua R. de Leeuw
Karl Rabe