The dataset contains EEG and behavioral data of 47 participants who completed 9 runs (i.e. copy-spelled 9 words) in a P300 speller task, as well as a random dot motion (RDM) task and questionnaires in a single experimental session. Details of the experimental protocol can be found here: Noble SC, Woods E, Ward T, Ringwood JV. “Adaptive P300-Based Brain-Computer Interface for Attention Training: Protocol for a Randomized Controlled Trial.” JMIR Res Protoc 2023, 12:e46135, doi: 10.2196/46135 A journal article describing the results of the study can be found here:Noble SC, Woods E, Ward T, Ringwood JV. “Accelerating P300-Based Neurofeedback Training for Attention Enhancement Using Iterative Learning Control: A Randomised Controlled Trial.” J Neural Eng 2024, 21(2), doi: 10.1088/1741-2552/ad2c9e Please cite the results paper when using the data. Each participant folder contains: [xxx]-raw.[xxx] – unprocessed EEG signals (in mV) from 32 electrodes for all 9 P300 speller runs in Openvibe (.ov) and Matlab (.mat) file formats, see details of the runs below [xxx]-processed.[xxx] – contains 3 xDAWN components extracted by the xDAWN spatial filter according to the weights in “spatial-filter.cfg” classifier.cfg - LDA classifier weights spatial-filter.cfg - xDAWN spatial filter weights log.txt - contains the group assignment, start and end time of the experiment, and performance in the P300 speller and RDM tasks The file “Subject Information.csv” contains the age and gender of all participants. The file “Questionnaire scores.csv” contains the responses to the questionnaire described in the experimental protocol and the NASA Task Load Index (TLX) for all participants. The .ov and .mat files contain data from the following runs: Filename Word to be copy-spelled Number of flashes per row and column Feedback given to participant calibration-signal1 THE 12 no calibration-signal2 QUICK 12 no calibration-signals Concatenation of calibration-signal1 and calibration-signal2 eval DOG 12 yes training-run-1 BEAUTIFUL 10 yes training-run-2 to training-run-5 BEAUTIFUL varying yes post-training-run DANCE 12 yes This research is supported by the Irish Research Council under project ID GOIPG/2020/692 and Science Foundation Ireland under grant number 12/RC/2289_P2.