{"success":true,"database":"eegdash","data":{"_id":"6972ce60897a7725c66f3c62","dataset_id":"ds006979","associated_paper_doi":null,"authors":["Hanane Ramzaoui","Melissa Beck"],"bids_version":"1.7.0","contact_info":["Hanane Ramzaoui"],"data_processed":true,"dataset_doi":"doi:10.18112/openneuro.ds006979.v1.0.1","datatypes":["eeg"],"demographics":{"subjects_count":53,"ages":[],"age_min":null,"age_max":null,"age_mean":null,"species":null,"sex_distribution":null,"handedness_distribution":null},"experimental_modalities":null,"external_links":{"source_url":"https://openneuro.org/datasets/ds006979","osf_url":null,"github_url":null,"paper_url":null},"funding":["n/a"],"license":"CC0","name":"Examining Perceptual Grouping on Stages of Processing in Visual Working Memory: An ERP Study","readme":"# BIDS-EEG Dataset: Examining Perceptual Grouping on Stages of Processing in Visual Working Memory: An ERP Study\n**Authors: Hanane Ramzaoui, Melissa Beck**\n## 1. Description: Project Overview\nWe present an electrophysiological dataset recorded from fifty-three subjects performing a bilateral change-detection task to investigate how perceptual grouping, based on color repetition, influences Visual Working Memory (VWM) processing efficiency.\nThe study is designed to temporally isolate and measure the neural correlates of several critical VWM stages: **individuation encoding**, **maintenance**, **initial comparison**, **percept-memory comparison**, and **decision making/late comparison**. This is achieved using specific **Event-Related Potential (ERP) markers** (N2pc, CDA, N2, FN400).\n---\n## 2. Experimental Task and Conditions\nSubjects were cued to encode the colors of 2 or 3 squares in one visual hemifield. After a maintenance period, a single-item probe was presented to determine if its color had changed.\n### Key Manipulations\nThe memory array contained four primary conditions:\n* **Unrepeated (UR):** Arrays with 2 or 3 unique colors (**2-UR, 3-UR**).\n* **Repeated (R):** Arrays with 3 items, where two colors were repeated. This condition was further subdivided based on spatial arrangement:\n    * Two repeated colors with strong spatial proximity **(3-RSP)**.\n    * Two repeated colors with weak spatial proximity **(3-RWP)**.\nThe Probe in Repeated Conditions\nIn the repeated conditions (3-RSP and 3-RWP), the single-item probe could test two different item types for change detection:\n* **Repeated Item:** The probe tests one of the two squares that share the same color.\n* **Unrepeated Item (Singleton):** The probe tests the single square with the unique color.\n---\n## 3. Primary Neurophysiological Measurements\nThe study leverages the following ERP components to index different VWM processing stages:\n| VWM Stage | ERP Marker | Event Locking |\n| :--- | :--- | :--- |\n| **Individuation Encoding** | **N2pc** | Stimulus-Locked |\n| **Maintenance/Load** | **CDA** (Contralateral Delay Activity) | Stimulus-Locked |\n| **Initial Comparison** | **N2pc** | Probe-Locked |\n| **Percept-Memory Comparison** | **N2** | Probe-Locked |\n| **Decision Making/Late Comparison** | **FN400** | Probe-Locked |\n---\n## 4. Acquisition Details and Structure\n### Acquisition Parameters\n| Parameter | Detail |\n| :--- | :--- |\n| **Subjects (N)** | 53 (N=39 used for stimulus-locked ERPs, see `participants.tsv` for details) |\n| **Electrode System** | BioSemi ActiveTwo System |\n| **Number of Channels** | 71 (64 scalp, 3 EOG, 2 Mastoid, 1 CMS/DRL) |\n| **Sampling Rate (Acquisition)** | 512 Hz |\n| **Total Trials** | 1248 trials |\n### BIDS Compliance\nThe data is structured following the Brain Imaging Data Structure (BIDS) standard for EEG.\n* **Acquisition Parameters:** Detailed recording specifications (e.g., 512 Hz sampling rate, Sinc filter details) are provided in the task-level BIDS JSON files (task-myexperiment_eeg.json).\n* **Methodology:** Comprehensive details on offline preprocessing (e.g., re-referencing to average mastoids, ICA artifact removal, 0.1 Hz high-pass filtering) and the precise analysis plan (e.g., ERP measurement windows, HEOG artifact thresholds, channel clusters) are provided in the stage 1 protocol on OSF (https://doi.org/10.17605/OSF.IO/8ZS96).\n---\n## 5. Event Codes/Triggers\nThe following table maps the trigger codes recorded in the EEG data to the specific experimental events.\n* **Acronym Key:** UR = Unrepeated; RWP = Repeated Weak Proximity; RSP = Repeated Strong Proximity.\n| Trigger Code | Event Description |\n| :---: | :--- |\n| \"11\" | Stimulus: 2-UR \\| Left Cue \\| Change \\| Unrepeated Probe |\n| \"12\" | Stimulus: 3-UR \\| Left Cue \\| Change \\| Unrepeated Probe |\n| \"13\" | Stimulus: 3-RWP \\| Left Cue \\| Change \\| Unrepeated Probe |\n| \"14\" | Stimulus: 3-RSP \\| Left Cue \\| Change \\| Unrepeated Probe |\n| \"17\" | Stimulus: 3-RWP \\| Left Cue \\| Change \\| Repeated Probe |\n| \"18\" | Stimulus: 3-RSP \\| Left Cue \\| Change \\| Repeated Probe |\n| \"19\" | Stimulus: 2-UR \\| Left Cue \\| No-Change \\| Unrepeated Probe |\n| \"20\" | Stimulus: 3-UR \\| Left Cue \\| No-Change \\| Unrepeated Probe |\n| \"21\" | Stimulus: 3-RWP \\| Left Cue \\| No-Change \\| Unrepeated Probe |\n| \"22\" | Stimulus: 3-RSP \\| Left Cue \\| No-Change \\| Unrepeated Probe |\n| \"25\" | Stimulus: 3-RWP \\| Left Cue \\| No-Change \\| Repeated Probe |\n| \"26\" | Stimulus: 3-RSP \\| Left Cue \\| No-Change \\| Repeated Probe |\n| \"27\" | Stimulus: 2-UR \\| Right Cue \\| Change \\| Unrepeated Probe |\n| \"28\" | Stimulus: 3-UR \\| Right Cue \\| Change \\| Unrepeated Probe |\n| \"29\" | Stimulus: 3-RWP \\| Right Cue \\| Change \\| Unrepeated Probe |\n| \"30\" | Stimulus: 3-RSP \\| Right Cue \\| Change \\| Unrepeated Probe |\n| \"33\" | Stimulus: 3-RWP \\| Right Cue \\| Change \\| Repeated Probe |\n| \"34\" | Stimulus: 3-RSP \\| Right Cue \\| Change \\| Repeated Probe |\n| \"35\" | Stimulus: 2-UR \\| Right Cue \\| No-Change \\| Unrepeated Probe |\n| \"36\" | Stimulus: 3-UR \\| Right Cue \\| No-Change \\| Unrepeated Probe |\n| \"37\" | Stimulus: 3-RWP \\| Right Cue \\| No-Change \\| Unrepeated Probe |\n| \"38\" | Stimulus: 3-RSP \\| Right Cue \\| No-Change \\| Unrepeated Probe |\n| \"41\" | Stimulus: 3-RWP \\| Right Cue \\| No-Change \\| Repeated Probe |\n| \"42\" | Stimulus: 3-RSP \\| Right Cue \\| No-Change \\| Repeated Probe |\n| \"51\" | Probe Onset event: 2-UR \\| Left Cue |\n| \"52\" | Probe Onset event: 3-UR \\| Left Cue |\n| \"53\" | Probe Onset event: 3-RWP \\| Left Cue |\n| \"54\" | Probe Onset event: 3-RSP \\| Left Cue |\n| \"55\" | Probe Onset event: 2-UR \\| Right Cue |\n| \"56\" | Probe Onset event: 3-UR \\| Right Cue |\n| \"57\" | Probe Onset event: 3-RWP \\| Right Cue |\n| \"58\" | Probe Onset event: 3-RSP \\| Right Cue |\n| \"120\" | Manual Response: Correct. |\n| \"121\" | Manual Response: Incorrect. |\n---\n## 6. Protocol Registration and Reference\nFor this dataset project, the approved Stage 1 protocol (registered report) can be found at this OSF link (2024, October 15): https://doi.org/10.17605/OSF.IO/8ZS96\n---\n## 7. Contact and Ethics\n* **Affiliation:** Louisiana State University\n* **Ethical Approval:** Institutional Review Board of Louisiana State University (IRBAM-23-0273 from March 1, 2023)\n* **Contact:** hramzaoui@lsu.edu","recording_modality":["eeg"],"senior_author":"Melissa Beck","sessions":[],"size_bytes":41389026706,"source":"openneuro","study_design":null,"study_domain":null,"tasks":["rest","test","visualworkingmemorytask"],"timestamps":{"digested_at":"2026-04-22T12:29:53.837696+00:00","dataset_created_at":"2025-11-30T23:31:46.262Z","dataset_modified_at":"2026-03-05T08:37:15.000Z"},"total_files":56,"contributing_labs":null,"ingestion_fingerprint":"207d1c1fb5596862186bffff5576a091cd2a24df003862860d9fa54b65223db9","n_contributing_labs":null,"storage":{"backend":"s3","base":"s3://openneuro.org/ds006979","raw_key":"dataset_description.json","dep_keys":["CHANGES","README.md","datacite.yml","participants.json","participants.tsv","task-visualworkingmemorytask_eeg.json","task-visualworkingmemorytask_events.json"]},"computed_title":"Examining Perceptual Grouping on Stages of Processing in Visual Working Memory: An ERP Study","nchans_counts":[{"val":69,"count":53},{"val":72,"count":1}],"sfreq_counts":[{"val":512.0,"count":55},{"val":500.0,"count":1}],"stats_computed_at":"2026-04-22T23:16:00.312441+00:00","total_duration_s":null,"tagger_meta":{"config_hash":"3557b68bca409f28","metadata_hash":"0676ab7e37316c36","model":"openai/gpt-5.2","tagged_at":"2026-04-07T09:32:40.872789+00:00"},"tags":{"pathology":["Healthy"],"modality":["Visual"],"type":["Memory"],"confidence":{"pathology":0.7,"modality":0.9,"type":0.85},"reasoning":{"few_shot_analysis":"Closest few-shot convention match for Type is the digit-span dataset (few-shot: \"EEG...digit span task\") which is labeled Type=Memory because the primary construct is working memory load/maintenance/recall. The current dataset likewise explicitly targets \"Visual Working Memory (VWM)\" stages using a change-detection paradigm, so the same Memory-type convention applies. Closest few-shot match for Modality is any visually driven cognitive task (e.g., the motor movement/imagery dataset is Modality=Visual because stimuli are screen targets; similarly here stimuli are colored squares on screen). No few-shot example suggests a clinical recruitment, so defaulting to Healthy when no diagnosis is stated follows the general convention across examples.","metadata_analysis":"Key population/task/stimulus facts from README:\n- Population: \"dataset recorded from fifty-three subjects\" (no diagnosis/clinical recruitment described anywhere in provided metadata).\n- Task/construct: \"bilateral change-detection task to investigate how perceptual grouping... influences Visual Working Memory (VWM)\".\n- Visual stimuli: \"encode the colors of 2 or 3 squares in one visual hemifield\" and \"a single-item probe was presented to determine if its color had changed\".\n- Explicit VWM staging/ERPs: \"neural correlates of several critical VWM stages\" and ERP markers (\"N2pc, CDA, N2, FN400\").\nAlso notes tasks list includes \"visualworkingmemorytask\" (and also \"rest\", \"test\").","paper_abstract_analysis":"No useful paper information.","evidence_alignment_check":"Pathology:\n- Metadata says: \"fifty-three subjects\" with no mention of any disorder/diagnosis; no patient/control groups described.\n- Few-shot pattern suggests: in absence of explicit clinical recruitment, label as Healthy.\n- Alignment: ALIGN (no conflict).\n\nModality:\n- Metadata says: \"encode the colors of 2 or 3 squares in one visual hemifield\"; \"single-item probe\"; \"bilateral change-detection\".\n- Few-shot pattern suggests: screen-based stimulus tasks with visual items map to Modality=Visual.\n- Alignment: ALIGN.\n\nType:\n- Metadata says: \"Visual Working Memory (VWM) processing efficiency\" and aims to measure \"VWM stages\" (encoding/maintenance/comparison) in a change-detection task.\n- Few-shot pattern suggests: working-memory paradigms (e.g., digit span) map to Type=Memory, even if decisions/responses occur.\n- Alignment: ALIGN (decision-making is mentioned as a stage, but the overarching construct is VWM).","decision_summary":"Top-2 candidates (with head-to-head choice) and justification:\n\nPathology:\n1) Healthy — Evidence: no clinical recruitment described, only \"fifty-three subjects\"; no diagnosis terms appear.\n2) Unknown — Possible because health status is not explicitly stated.\nWinner: Healthy, because the metadata strongly indicates a standard cognitive EEG experiment without any clinical population description.\nConfidence basis: absence of any diagnosis/group terms + generic subject description.\n\nModality:\n1) Visual — Evidence: \"colors of 2 or 3 squares in one visual hemifield\"; \"single-item probe\"; \"bilateral change-detection task\".\n2) Resting State — Possible only because tasks list includes \"rest\", but README focus is the visual change-detection ERP experiment.\nWinner: Visual, because the dominant described paradigm is clearly visual and stimulus-driven.\nConfidence basis: multiple explicit visual-stimulus quotes.\n\nType:\n1) Memory — Evidence: explicitly \"Visual Working Memory (VWM)\"; \"maintenance period\"; ERP marker \"CDA (Contralateral Delay Activity)\" indexing maintenance/load.\n2) Perception — Possible because \"perceptual grouping\" is manipulated, but it is in service of VWM efficiency rather than pure perceptual discrimination.\nWinner: Memory, because the stated study goal is VWM stages/efficiency in change detection.\nConfidence basis: multiple explicit VWM/maintenance/change-detection statements and strong few-shot analog (digit span labeled Memory)."}},"canonical_name":null,"name_confidence":0.84,"name_meta":{"suggested_at":"2026-04-14T10:18:35.343Z","model":"openai/gpt-5.2 + openai/gpt-5.4-mini + deterministic_fallback"},"name_source":"author_year","author_year":"Ramzaoui2025"}}