Longitudinal Phenomena in Experimental Data

The analysis of experimental data using multilevel models (also known as linear mixed models) has become very popular in recent years, where experimental trials are considered as level 1 units nested within individuals (level 2). Another special feature of this data is that the trials are presented in a fixed temporal sequence, which means that this data can also be interpreted as longitudinal data. In our research, we investigate the possibilities that arise from this perspective on experimental data.

We focus on modeling various temporal phenomena in these data, including systematic trends and autoregressive carryover effects. Using simulation studies and real data examples, we investigate how temporal effects can be adequately represented and considered in various statistical modeling frameworks. To this end, we examine both “classical” linear mixed models (LMMs) and non-parametric extensions (e.g., splines), as well as structural equation models (SEMs, e.g., dynamic SEMs).

Relevant Publications:

Keintzel, S. L. G. M., Nikolei, A., & Scharf, F. (submitted). Why and How to Model Trends and Time-Varying Experimental Effects Using Mixed-Effects Models.

Keintzel, S. L. G. M., Wetzel, N, & Scharf, F. (2026). Analyzing the Dynamics of Auditory Distraction Using Multigroup Multilevel Structural Equation Modeling. Structural Equation Modeling: A Multidisciplinary Journal. 1-16. https://doi.org/10.1080/10705511.2025.2598602

Widmann, A., Herrmann, B., & Scharf, F. (2025). Pupillometry is sensitive to speech masking during story listening: A commentary on the critical role of modeling temporal trends. Journal of Neuroscience Methods, 413, 110299. https://doi.org/10.1016/j.jneumeth.2024.110299

Volkmer, S., Wetzel, N., Widmann, A., & Scharf, F. (2022). Attentional control in middle childhood is highly dynamic-Strong initial distraction is followed by advanced attention control. Developmental science, 25, e13275. https://doi.org/10.1111/desc.13275

Wetzel, N., Widmann, A., & Scharf, F. (2021). Distraction of attention by novel sounds in children declines fast. Scientific Reports, 11(1), 5308. doi/10.1038/s41598-021-83528-y 

Wetzel, N., Scharf, F., & Widmann, A. (2019). Can’t Ignore—Distraction by Task‐Irrelevant Sounds in Early and Middle Childhood. Child Development, 90(6), 454–464. doi/10.1111/cdev.13109