This site contains the behavioural data from the publication, Cortical State Fluctuations during Sensory Decision Making, by Jacobs et al in Current Biology.The data deposited here is from the behavioural tasks described in the publication. (The widefield and pupil data are deposited separately.) The data is organised by experimental subject; most subjects were recorded from on multiple days, which form subfolders within the subkect folder. Within a day, there may have been several experiments, which are again contained in the subfolders with the day folder. The companion code (https://github.com/eakjacobs/Jacobs_et_al_CurrentBiology) is structured according to this data organisation. The companion code also contains the information about which datasets were used in which analyses.The datasets can be in different formats; the companion code can handle all of them and transforms them into a standard format as part of the preprocessing. If there are any problems with this, please raise an issue on GitHub.Please also follow this link for more information: https://doi.org/10.6084/m9.figshare.13084805Link to research paper (freely available): https://www.cell.com/current-biology/fulltext/S0960-9822(20)31437-8