EEG audio-tactile spatial localization task under reduced alertness

This dataset contains raw EEG data recorded at the University of Granada (CIMCYC) between March and June 2025 during an audio–tactile spatial localization task. The experiment was conducted with healthy easy-sleepers seated in a reclining armchair for approximately 2 hours and a half, with the aim of investigating multisensory perceptual decision-making as participants transitioned from wakefulness towards sleep (https://osf.io/3kgjw/overview). Participants were instructed to localize an auditory target presented on the left or right while ignoring task-irrelevant tactile stimulation. Trials comprised auditory-only, spatially congruent audio–tactile, and spatially incongruent audio–tactile conditions. The experiment consisted of alternating periods designed to promote relatively high and low levels of alertness (Awake–Drowsy–Awake–Drowsy), while EEG was recorded continuously. Due to technical limitations when uploading the full EEG dataset converted to BIDS format, the data have been divided into compressed archives, each containing data from up to five participants: Subject_1_to_5.zip: data for participants sub-001 to sub-005 Subject_6_to_10.zip: data for participants sub-006 to sub-010 Subject_11_to_15.zip: data for participants sub-011 to sub-015 Subject_16_to_20.zip: data for participants sub-016 to sub-020 Subject_21_to_25.zip: data for participants sub-021 to sub-025 Subject_26_to_29.zip: data for participants sub-026 to sub-029 Subject_30_to_32.zip: data for participants sub-030 to sub-032 Each compressed archive follows the BIDS specification and contains raw EEG recordings, metadata, and event files corresponding to the audio–tactile spatial localization task. In addition to the EEG data, the dataset includes the following files: task-AudiotactileSpatialLocalization_events.json: Description of the event structure and event codes used in the task. participants.tsv and participants.json: Demographic and experimental information for each participant, following the BIDS standard. dataset_description.json: General description of the dataset in accordance with the BIDS specification. README: Overview of the dataset structure and content. CHANGES: Log of relevant changes and updates to the dataset. Redundancy_audio_project.mp3: Auditory stimulus used in the spatial localization task. BIDS conversion script: MATLAB script used to convert the original EEG recordings into BIDS format. chanlocs.mat: Channel location file containing electrode position information. The processed data and analysis code used for EEG preprocessing, trial-by-trial classification of alertness states, behavioural analyses, Hierarchical Drift Diffusion Model (HDDM) analyses, time-frequency analyses, multivariate pattern analyses (MVPA) and lateralized readiness potential (LRP) analyses are available on the Open Science Framework (OSF) repository associated with this study (https://osf.io/3kgjw/overview).