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MMA-82: A New Multi-Domain Benchmark for Micro-Action Recognition and Detection
Submitted to IEEE TMM 2026
Yanbin Hao*, Pengyu Liu*, Xing Wei, Xun Yang, Dan Guo, Meng Wang
Hefei University of Technology | University of Science and Technology of China
* Equal contribution
π Paper | π arXiv | π Project Page | π€ Dataset | β Code
π§ If you have any questions, please feel free to contact me: lpynow@gmail.com
π’ News
- π2026.06.23: Release of the Lab Interview Videos subset of the MMA-82-Rec dataset
- 2026.06.20: MMA-82 paper, project page, and dataset links are available.
- 2026.06.20: We introduce MMA-82, a multi-domain benchmark for micro-action recognition and multi-label temporal detection.
π Overview
MMA-82 extends micro-action analysis from controlled laboratory settings to realistic multi-domain scenarios. It expands the previous MA-52 label space from 52 to 82 fine-grained whole-body micro-action categories and covers four domains: laboratory interviews, psychiatric patient interviews, street interviews, and emotion-rich television videos.
MMA-82 is designed around two core tasks:
- Micro-Action Recognition: classify trimmed clips into fine-grained body-level and action-level micro-action categories.
- Multi-label Micro-Action Detection: localize and classify all micro-action instances in untrimmed videos, including dense or overlapping subtle actions.
The benchmark further supports in-domain, cross-domain, zero-shot, and few-shot evaluation protocols, making it a challenging testbed for realistic micro-action understanding.
π§ Quick Navigation
In this repository, we provide:
- π¦ MMA-82 Dataset: 79,574 annotated micro-action instances across four source domains.
- π§ͺ Benchmark Tasks: recognition and multi-label temporal detection.
- π Emotion Analysis: micro-actions as complementary affective cues.
- π Citation: BibTeX entry for citing MMA-82.
π¦ Dataset Scale
MMA-82 contains 82 action-level categories organized into seven body-level groups: Body, Head, Upper Limb, Lower Limb, Body-Hand, Head-Hand, and Leg-Hand.
| Split | Videos / Clips | Instances | Duration | Subjects | Description |
|---|---|---|---|---|---|
| MMA-82-Rec | 39,816 clips | 39,816 | 28.94h | 454 | Trimmed clips for micro-action recognition |
| MMA-82-Det | 11,180 videos | 39,758 | 46.93h | 434 | Untrimmed videos for multi-label temporal detection |
| Total | - | 79,574 | 75.87h | 454 | Four domains and 82 action categories |
MMA-82-Rec
MMA-82-Rec contains 39,816 trimmed clips. Each clip is annotated with a body-level group and an action-level micro-action category.
| Data Source | Train | Val | Test | Total Clips | Total Duration | Avg. Length | Subjects |
|---|---|---|---|---|---|---|---|
| Laboratory Interviews | 15,820 | 5,636 | 6,053 | 27,509 | 20.48h | 2.68s | 229 |
| Psychiatric Interviews | 4,203 | 1,398 | 1,410 | 7,011 | 5.72h | 2.94s | 19 |
| Street Interviews | 2,358 | 792 | 775 | 3,925 | 2.10h | 1.92s | 26 |
| Emotion Videos | 795 | 247 | 329 | 1,371 | 0.64h | 1.67s | 180 |
| Total | 23,176 | 8,073 | 8,567 | 39,816 | 28.94h | 2.62s | 454 |
MMA-82-Det
MMA-82-Det contains 11,180 untrimmed videos and 39,758 temporal action instances. Each video contains 3.56 micro-action instances on average, and each instance lasts approximately 3.66s.
π§ͺ Evaluation Protocols
Micro-Action Recognition
Given a trimmed video clip, the model predicts the target micro-action category at both action and body levels.
- In-domain setting: train, validation, and test splits come from the same source domain.
- Cross-domain zero-shot setting: train on laboratory interviews and test directly on another domain.
- Cross-domain few-shot setting: train on laboratory interviews and adapt with a small number of labeled target-domain samples.
- Metrics: Top-1 Acc, Top-5 Acc, mean class accuracy (MCA), Macro F1, and Micro F1.
Multi-label Micro-Action Detection
Given an untrimmed video, the model predicts a set of temporal action proposals:
(start_time, end_time, action_category, confidence_score)
- Goal: detect every micro-action instance and classify its category.
- Challenge: actions are short, subtle, dense, and may co-occur in rapid succession.
- Metrics: Detection-mAP at multiple temporal IoU thresholds, reported at both action and body levels.
π Baseline Results
Recognition: In-Domain Summary
The paper evaluates skeleton-based PoseC3D and RGB-based GC-TSM baselines. The table below reports action-level test metrics.
| Sub-Dataset | Method | Top-1 Acc | Top-5 Acc | MCA | Macro F1 |
|---|---|---|---|---|---|
| MMA-82-Rec (All) | Skeleton | 56.62 | 80.45 | 36.77 | 39.39 |
| MMA-82-Rec (All) | RGB | 60.43 | 86.14 | 38.98 | 39.56 |
| Laboratory Interviews | Skeleton | 64.84 | 87.81 | 44.88 | 47.03 |
| Laboratory Interviews | RGB | 68.15 | 92.83 | 48.01 | 46.48 |
| Psychiatric Interviews | Skeleton | 41.63 | 68.79 | 15.74 | 17.65 |
| Psychiatric Interviews | RGB | 46.74 | 72.13 | 14.10 | 13.64 |
| Street Interviews | Skeleton | 40.77 | 70.71 | 19.49 | 20.70 |
| Street Interviews | RGB | 39.87 | 73.55 | 12.75 | 12.56 |
| Emotion Videos | Skeleton | 7.29 | 17.93 | 3.72 | 3.11 |
| Emotion Videos | RGB | 25.53 | 52.89 | 12.20 | 11.05 |
Recognition: Cross-Domain Summary
PoseC3D is trained on laboratory interviews and evaluated on target domains under zero-shot and few-shot protocols.
| Target Domain | Protocol | Action Top-1 | Action Top-5 | Action MCA | Body Top-1 |
|---|---|---|---|---|---|
| Psychiatric Interviews | Zero-Shot | 27.30 | 50.28 | 14.25 | 68.58 |
| Psychiatric Interviews | 1-Shot | 30.27 | 58.62 | 22.82 | 72.48 |
| Psychiatric Interviews | 5-Shot | 30.12 | 58.60 | 22.72 | 72.60 |
| Psychiatric Interviews | 10-Shot | 30.13 | 58.59 | 22.71 | 72.64 |
| Street Interviews | Zero-Shot | 20.65 | 44.90 | 10.65 | 53.16 |
| Street Interviews | 1-Shot | 21.38 | 45.64 | 15.60 | 54.95 |
| Street Interviews | 5-Shot | 21.58 | 46.10 | 16.17 | 64.91 |
| Street Interviews | 10-Shot | 22.52 | 45.92 | 17.76 | 65.64 |
| Emotion Videos | Zero-Shot | 14.13 | 32.98 | 6.63 | 43.92 |
| Emotion Videos | 1-Shot | 17.26 | 39.77 | 14.00 | 41.43 |
| Emotion Videos | 5-Shot | 17.48 | 41.75 | 15.20 | 42.35 |
| Emotion Videos | 10-Shot | 17.70 | 42.53 | 15.43 | 42.03 |
Detection: AdaTAD on MMA-82-Det
| Backbone | Action mAP@0.2 | Action mAP@0.5 | Action mAP@0.7 | Action Avg | Body mAP@0.2 | Body mAP@0.5 | Body mAP@0.7 | Body Avg | AVG |
|---|---|---|---|---|---|---|---|---|---|
| VideoMAE-S | 20.88 | 12.72 | 5.56 | 12.09 | 48.18 | 28.78 | 13.91 | 25.44 | 18.77 |
| VideoMAE-B | 22.62 | 14.67 | 6.32 | 13.59 | 50.95 | 30.46 | 12.23 | 29.13 | 21.36 |
| VideoMAE-L | 22.74 | 15.60 | 7.68 | 14.98 | 55.48 | 33.01 | 14.06 | 31.83 | 23.41 |
| VideoMAE-H | 26.53 | 17.56 | 7.55 | 16.08 | 54.71 | 33.64 | 14.17 | 30.05 | 23.07 |
π Emotion and Micro-Actions
MMA-82 also studies how micro-actions relate to affective states. The paper shows that micro-actions are strongly associated with emotions and provide complementary cues beyond facial micro-expressions.
| Setting | Method | Top-1 Acc | F1 |
|---|---|---|---|
| Micro-Expression Only | DeepFace | 22.86 | 17.54 |
| Micro-Action Only | TSM | 32.38 | 31.86 |
| Both | DeepFace + TSM | 32.86 | 32.36 |
Key observations:
- Sad and melancholy both correlate with bowing head and turning head.
- Sad contains more explicit negative bodily actions, while melancholy is subtler and more inward.
- Micro-actions alone outperform facial micro-expression cues under the reported setup.
- Combining micro-actions and micro-expressions improves over the facial baseline.
π₯ Dataset
The dataset page is available on Hugging Face:
hf download lpynow/MAR_plus_plus \
--repo-type dataset \
--local-dir data/MMA-82
Please refer to the released dataset card and project page for the latest file organization, annotation format, and usage notes.
π Citation
If you find MMA-82 useful for your research, please consider citing our paper:
@misc{hao2026newmultidomainbenchmarkmicroaction,
title={A New Multi-Domain Benchmark for Micro-Action Recognition and Detection},
author={Hao, Yanbin and Liu, Pengyu and Wei, Xing and Yang, Xun and Guo, Dan and Wang, Meng},
year={2026},
eprint={2606.14096},
archivePrefix={arXiv},
primaryClass={cs.CV},
url={https://arxiv.org/abs/2606.14096}
}
π Acknowledgement
We thank the authors of MA-52, MMA-52, PoseC3D, GC-TSM, AdaTAD, VideoMAE, DeepFace, and related micro-action / micro-expression benchmarks for their inspiring work.
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