Our mission is to improve psychological science in two ways: by developing research methodology and by contributing novel psychological theory. Our cross-cutting vision is that these two strands of science are intertwined: Good substantive theories can be represented in mathematical form, and because formalized substantive theories are closely connected to statistical models, developing methodology goes hand in hand with developing theory. The simultaneous development of novel substantive theories and methodologies suited to test them defines the unique and internationally acclaimed focus of our group.
With this general objective, the group focuses on a number of more specific conceptual and empirical challenges in psychological research. First, much of the research concerns matters that involve the conceptual foundations of psychology and psychometrics. This involves the analysis of psychometric concepts such as validity, reliability, and measurement levels, but also of psychological concepts like general intelligence, psychopathology, and personality. Second, a theme that runs through the program is the analysis of data that involve the factor time. This covers, for instance, online adaptive testing procedures, the analysis of learning curves, regime-switching models, and the modeling of speed accuracy trade-offs. Third, a general theme concerns the analysis of individual differences, especially in relation to differences between groups. This theme includes research on measurement invariance, selection, behavior genetics, and latent variable modeling. Finally, a recent addition to this spectrum is the analysis of neuroscientific data, involving models for fMRI and EEG/MEG data, but also covering the question of how we should jointly model neurological and behavioral measures.