Joshua R. de Leeuw

Associate Professor of Cognitive Science
Joshua R. de Leeuw wearing a pink collared shirt with trees in the background.

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-Northwest
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

Grants, Fellowships, Honors, Awards

Joshua de Leeuw, Associate Professor of Cognitive Science, Receives NIH Funding
Joshua de Leeuw, Associate Professor of Cognitive Science, has received grant funding from the NIH in collaboration with his colleague from MIT for the project “Psych-DS: A FAIR data standard for behavioral datasets.” This three-year project is an important step forward for scientific efforts that rely on behavioral data; the standardized representation of behavioral data into machine-readable formats is a critical first step for the development of new scientific tools that can accelerate the pace of neuroscience and biomedical research.

In the Media

Robots and Friendships Competition Winners

Twenty students in Assistant Professor Joshua deLeeuw’s Cognitive Science 320 class designed and built their own autonomous robots. Emmett, a robot that wasn’t working until the very end of the semester, rose to the occasion at Vassar’s annual Autonomous Robot Design Competition.


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