Postdoctoral researcher at the University of Amsterdam

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I am an assistant professor at the Psychological Methods Unit of the University of Amsterdam. My research focuses on Bayesian hierarchical modeling of cognitive phenomena such as interference effects (Does everyone Stroop?), recognition memory, and subliminal priming. I am mainly interested in individual differences in cognitive tasks and how to disentangle stable, qualitative individual differences from sample noise.

Even though a large part of my research is developing statistical models, I am an experimental psychologist at heart, and I get excited about innovative, bold experimental designs. But I also believe that statistics are important to express and test psychological theory. And that Bayesian statistics are better suited to do so than conventional t-tests or ANOVA. My work particularly focuses on the usefulness of ordinal constraints in modeling. It seems that ordinal constraints are particularly well suited to capture theoretical predictions in psychology.

Before my current position I was a postdoctoral research fellow working with EJ Wagenmakers at the Department of Psychological Methods (University of Amsterdam). Prior to that I earned my PhD in quantitative psychology from the University of Missouri working with Jeff Rouder.

Throughout my research, I try to be transparent and provide data, code, and open access to manuscripts I wrote. Click here for a list of publications.

And this is Frank, my cat.



van den Bergh, D., Haaf, J. M., Ly, A., Rouder, J. N., Wagenmakers, E.-J. (submitted). A Cautionary Note on Estimating Effect Size. PsyArXiv. PDF

van Doorn, J., van den Bergh, D., Boehm, U., Dablander, F., Derks, K., Draws, T., Evans, N.J., Gronau, Q. F., Haaf, J. M., Hinne, M., Kucharsky, S., Ly, A., Marsman, M., Matzke, D., Raj, A.K.N., Sarafoglou, A., Stefan, A., Voelkel, A.G., & Wagenmakers, E.-J. (submitted) The JASP guidelines for conducting and reporting a Bayesian analysis. PsyArXiv. PDF

Gronau, Q. F., Heck, D., Berkhout, S., Haaf, J. M., & Wagenmakers, E. (submitted). A Primer on Bayesian Model-Averaged Meta-Analysis. PsyArXiv. PDF

Haaf, J. M., Hoogeveen, S., Berkhout, S., Gronau, Q. F., & Wagenmakers, E. J. (2020). A Bayesian Multiverse Analysis of Many Labs 4: Quantifying the Evidence against Mortality Salience. PsyArXiv. PDF GitHub

Haaf, J. M., Klaassen, F., & Rouder, J. N. (submitted). Capturing Ordinal Theoretical Constraint in Psychological Science. PsyArXiv. PDF

Haaf, J. M., Rhodes, S., Sun, T. K., Naveh-Benjamin, M., & Rouder, J. N. (submitted). Revisiting the Remember-Know Task: Replications of Gardiner and Java (1990). PsyArxiv. OSF project & PDF

Rouder, J. N., Haaf, J. M. (submitted). Beyond Means: Are There Stable Qualitative Individual Differences in Cognition? PsyArxiv. PDF

Rouder, J. N., & Haaf, J. M. (submitted). Optional Stopping and the Interpretation of The Bayes Factor. PsyArXiv. PDF

Rouder, J. N., Kumar, A., & Haaf, J. M. (submitted). Why Most Studies of Individual Differences With Inhibition Tasks Are Bound To Fail. PsyArxiv. PDF

In Press

Haaf, J. M., Merkle, E. C., & Rouder, J. N. (in press). Assessing Item Ordering With Shift-Scale Models. Journal of Mathematical Psychology. PDF


Aust, F., Haaf, J. M., & Stahl, C. (2019). A memory-based judgment account of expectancy-liking dissociations in evaluative conditioning. Journal of Experimental Psychology: Learning, Memory, and Cognition, 45(3), 417-439. htp:// . PDF & OSF project

Haaf, J. M., Ly, A., & Wagenmakers, E.-J. (2019). Retire significance, but still test hypotheses. Nature, 567, 461.

Haaf, J. M., & Rouder, J. N. (2019). Some do and some don’t? Accounting for variability of individual difference structures. Psychonomic Bulletin and Review, 26(3), 772-789. PDF

Rouder, J. N., & Haaf, J. M. (2019). A Psychometrics of Individual Differences in Experimental Tasks. Psychonomic Bulletin and Review, 26(2), 452-467. PDF

Rouder, J. N., Haaf, J. M., Davis-Stober, C., & Hilgard, J. (2019). Beyond overall effects: A Bayesian approach to finding constraints across a collection of studies in meta-analysis. Psychological Methods. PDF

Rouder, J. N., Haaf, J. M., & Snyder, H. K. (2019). Minimizing Mistakes In Psychological Science. Advances in Methods and Practices in Psychological Science, 2(1), 3-11. PDF

Snyder, H. K., Rafferty, S. M., Haaf, J. M., & Rouder, J. N. (2019). Common or Distinct Attention Mechanisms for Contrast and Assimilation. Attention, Perception, & Psychophysics, 81(6). 1944-1950. PDF


Etz, A., Haaf, J. M., Rouder, J. N., & Vandekerckhove, J. (2018). Bayesian inference and testing any hypothesis you can specify. Advances in Methods and Practices in Psychological Science, 1(2), 281-295. PDF & OSF project (with app)

Heycke, T., Gehrmann, S. M., Haaf, J., & Stahl, C. (2018). Of two minds or one? A registered replication of Rydell et al. (2006). Emotion and Cognition, 32(8). PDF & OSF project

Rouder, J. N., Haaf, J. M., & Vandekerckhove, J. (2018). Bayesian Inference in Psychology, Part IV: Parameter estimation and Bayes factors. Psychonomic Bulletin and Review, 25(1), 102-113. 10.3758/s13423-017-1420-7. PDF

Rouder, J., & Haaf, J. (2018). Power, Dominance, and Constraint: A Note on the Appeal of Different Design Traditions. Advances in Methods and Practice in Psychological Science, 1(1), 19-26. PDF Github

Rouder, J. N., Haaf, J. M., & Aust, F. (2018). From theories to models to predictions: A Bayesian model comparison approach. Communication Monographs, 85(1), 41-56. 10.1080/03637751.2017.1394581. PDF


Haaf, J. M., & Rouder, J. N. (2017). Developing Constraint in Bayesian Mixed Models. Psychological Methods, 22(4), 779-798. PDF Github

Thiele, J. E., Haaf, J. M., & Rouder, J. N. (2017). Is there variation across individuals in processing? Bayesian analysis for systems factorial technology. Journal of Mathematical Psychology, 81, 40-54. 10.1016/ PDF Github


Stahl, C., Haaf, J., & Corneille, O. (2016). Subliminal evaluative conditioning? Above-chance CS identification may be necessary and insufficient for attitude learning. Journal of Experimental Psychology: General, 145(9), 1107-1131. /10.1037/xge0000191. PDF Github



Upcoming Talks and Workshops

Recent Invited Talks and Workshops

Invite Me! I enjoy giving workshops and talks. If you would like to invite me to your university, contact me. My expertise is in Bayesian hierarchical modeling, individual differences, meta-analysis, and reproducible coding in R.



Julia Haaf
Psychological Methods
Nieuwe Achtergracht 129-B | Room G0.34
University of Amsterdam

New Email: j.m.haaf [at] uva [dot] nl

If you are interested in working with me on a project I am happy to hear from you!

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