The raw SSVEP data for each participant are contained in tar files (around 800MB each), containing individual files for each block in gzipped csv format. Details of the file format are described here: https://bakerdh.wordpress.com/2019/02/23/open-eeg-data/
The data were converted using the script [d_EEG2CSV.m][1], which uses functions from [EEGlab][2] to import the data.
The [headerfile.csv][3] contains further information about the experiment, which is described in the main power contours manuscript, and also in the original paper by [Vilidaite et al. (2018)][4].
Note that S75 is missing as they completed only one block of the experiment and then withdrew.
[1]: https://osf.io/v4ejq/
[2]: https://sccn.ucsd.edu/eeglab/index.php
[3]: https://osf.io/myrbe/
[4]: http://dx.doi.org/10.1098/rspb.2018.2255