This material includes the experimental program, the instructions, the data, as well as the computer code and results to reproduce the analysis reported in Rausch, M., Zehetleitner, M., Steinhauser, M., & Maier, M. E. (2020). Cognitive modelling reveals distinct electrophysiological markers of decision confidence and error monitoring. *NeuroImage, 218*, 116963. https://doi.org/10.1016/j.neuroimage.2020.116963 The file "Materials&Behavioral.zip" contains the experimental program, the original instructions (in german) and the behavioural raw data. The file "EEG_RawData_SBJ_01-13.zip" contains the raw eeg data of participants 1 - 13. The file "EEG_RawData_SBJ_14-25.zip" contains the raw eeg data of participants 14 - 25. The file "Analysis.zip" includes the computer code to reproduce all results and figures reported in the paper. The experiment was conducted using PsychoPy 1.83.04 running on Windows 8. To reproduce the analysis, download and unpack all data on your local hard drive. The Python and R scripts begin with setting the path; please insert the path to the folder where ever you have stored the files. We conducted the analysis using Python 3.6.5 with the modules mne 0.16.1, numpy 1.14.3, and pandas 0.23.0 and R R 3.3.3 (64-bit) with the packages ggplot2 2.2.1, plyr 1.8.4, BayesFactor 0.9.12, snow 0.4.2, doSNOW 1.0.14, and R.utils 2.5.0 on a PC running on Windows 10. All material is licensed under a CC-BY-NC-SA 4.0 license. For a human-readable summary of what you are allowed to do with that piece of work, see https://creativecommons.org/licenses/by-nc-sa/4.0/