Dataset at a Glance

The Active Visual Semantics (AVS) dataset combines MEG and eye-tracking data recorded while participants visually explored natural scenes, along with structural MRI scans acquired before the first MEG session. By focusing on active vision, it moves beyond the passive, fixation-enforced viewing paradigms used in most existing neuroimaging datasets.

Participants

5 (see Participants)

Sessions

10 MEG + eye-tracking sessions per participant, plus one anatomical session. 10 runs in ses-01, 14 in ses-02 – ses-10; 30 trials per run, so 4,080 trials (one per scene) per participant

Stimuli

4,080 natural scenes from the Natural Scenes Dataset (NSD), semantically balanced (see Stimuli)

Task

Active viewing (4 s/scene) with a verbal scene-captioning task on 25% of trials (see Semantic Captioning Task)

MEG

306-channel Elekta Neuromag TRIUX, 1000 Hz (see MEG Acquisition)

Eye tracking

EyeLink 1000, 1000 Hz (see Eye Tracking)

Fixation epochs

More than 200,000 across the dataset. Shipped fixation- and saccade-locked, -0.5 to 0.8 s at 500 Hz, with per-epoch metadata

Object labels

Per-fixation MS-COCO / COCO-Stuff category labels, 171 categories (see Fixation Object Labeling)

Anatomy

Defaced individual T1 plus a ready-to-use FreeSurfer SUBJECTS_DIR (cortex only – source space, BEM, forward solution, coregistration, parcellations)

Release size

22,488 files, 663.1 GiB in total – but the tree is designed for selective download (see Data Access)

For the release layout and file formats, see Dataset Structure; for known data-quality caveats, see Known Issues; for how to get the data, see Data Access.

What Do I Need?

Goal

Start here

Load MEG + eye-tracking data for an analysis

AVSComposer Guide, Quick Start Guide

Understand the acquisition/preprocessing pipeline

Methods

Source reconstruction / population codes

Source Reconstruction and Population Codes

Map fixations to scene objects

Fixation Object Labeling, COCO-Stuff Object Detection

Work out which parts of the dataset to download

Data Access

See example analyses (RSA, encoding, source ERFs)

Example Analyses

Full function/class reference

API Reference