Perceptual Intelligence: Modeling Human Interactions

Nuria Oliver, Barbara Rosario and Alex Pentland — MIT Media Lab

Detection was only the start. The harder problem was recognizing what was happening between two people: whether they were meeting, following one another, changing direction to talk, or continuing separately.

The system combined bottom-up visual tracking with top-down behavioral models in a feedback loop. Hidden Markov models represented individual activity; coupled hidden Markov models represented the dependencies between two people. The experiments found that the coupled models recognized interactions more efficiently and accurately than treating each person's behavior independently.

Real labeled footage was scarce. A synthetic-agent simulator supplied examples instead, and models trained on those generated trajectories could then classify real sequences without additional tuning. It was an unusual shortcut, but a practical response to the cost of collecting interaction video in the late 1990s.

The evaluation covered a defined vocabulary of encounters, such as following, meeting, talking, and separating, rather than unrestricted social behavior. Its success on those sequences therefore should not be read as general understanding of people's intentions.

This work became the central experimental line in Nuria Oliver's doctoral thesis, Towards Perceptual Intelligence. The thesis also connected it to LAFTER's face and expression tracking, coupled models for two-handed actions, and driver behavior in the SmartCar.

Human-interaction models

Conference paper
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Formatted citation

Nuria Oliver, Barbara Rosario, Alex Pentland (1998). Statistical modeling of human interactions. CVPR Workshop on Interpretation of Visual Motion, 39-46. https://nuriaoliver.com/papers/cvpr98.pdf

BibTeX
@inproceedings{oliver1998statistical,
  author = {Oliver, Nuria and Rosario, Barbara and Pentland, Alex},
  title = {Statistical modeling of human interactions},
  booktitle = {CVPR Workshop on Interpretation of Visual Motion},
  year = 1998,
  pages = {39--46},
  url = {https://nuriaoliver.com/papers/cvpr98.pdf},
  cites = 54
}

Statistical modeling of human interactions

Nuria Oliver, Barbara Rosario, Alex Pentland
CVPR Workshop on Interpretation of Visual Motion · 1998
Conference paper
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Formatted citation

Nuria Oliver, Barbara Rosario, Alex Pentland (1999). A Bayesian computer vision system for modeling human interactions. International Conference on Computer Vision Systems (ICVS). Springer, 255-272. https://doi.org/10.1007/3-540-49256-9_16

BibTeX
@inproceedings{oliver1999bayesian,
  author = {Oliver, Nuria and Rosario, Barbara and Pentland, Alex},
  title = {A Bayesian computer vision system for modeling human interactions},
  booktitle = {International Conference on Computer Vision Systems (ICVS). Springer},
  year = 1999,
  pages = {255--272},
  doi = {10.1007/3-540-49256-9_16},
  cites = 2255,
  citesdate = {2026-03-23}
}
★ 2,255 citations

A Bayesian computer vision system for modeling human interactions

Nuria Oliver, Barbara Rosario, Alex Pentland
International Conference on Computer Vision Systems (ICVS). Springer · 1999
Conference paper
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Formatted citation

Nuria Oliver, Barbara Rosario, Alex Pentland (1999). Graphical Models for Recognizing Human Interactions. Advances in Neural Information Processing Systems (NIPS 1999), 924-930. https://proceedings.neurips.cc/paper_files/paper/1998/hash/3a20f62a0af1aa152670bab3c602feed-Abstract.html

BibTeX
@inproceedings{oliver1999graphical,
  author = {Nuria Oliver and Barbara Rosario and Alex Pentland},
  title = {Graphical Models for Recognizing Human Interactions},
  booktitle = {Advances in Neural Information Processing Systems (NIPS 1999)},
  pages = {924--930},
  year = 1999,
  url = {https://proceedings.neurips.cc/paper_files/paper/1998/hash/3a20f62a0af1aa152670bab3c602feed-Abstract.html},
  cites = 63
}

Graphical Models for Recognizing Human Interactions

Nuria Oliver, Barbara Rosario, Alex Pentland
Advances in Neural Information Processing Systems (NIPS 1999) · 1999
Conference paper
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Barbara Rosario, Nuria Oliver, Alex Pentland (1999). A Synthetic Agent System for Bayesian Modeling of Human Interactions. Proceedings of the 3rd Annual Conference on Autonomous Agents (ICAA 1999), 342-343. https://doi.org/10.1145/301136.301225

BibTeX
@inproceedings{rosario1999synthetic,
  author = {Barbara Rosario and Nuria Oliver and Alex Pentland},
  title = {A Synthetic Agent System for {Bayesian} Modeling of Human Interactions},
  booktitle = {Proceedings of the 3rd Annual Conference on Autonomous Agents (ICAA 1999)},
  pages = {342--343},
  year = 1999,
  doi = {10.1145/301136.301225},
  cites = 9,
  citesdate = {2026-03-23}
}

A Synthetic Agent System for Bayesian Modeling of Human Interactions

Barbara Rosario, Nuria Oliver, Alex Pentland
Proceedings of the 3rd Annual Conference on Autonomous Agents (ICAA 1999) · 1999
Journal paper
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Nuria Oliver, Barbara Rosario, Alex P. Pentland (2000). A Bayesian Computer Vision System for Modeling Human Interactions. IEEE Transactions on Pattern Analysis and Machine Intelligence 22(8), 831-843. https://doi.org/10.1109/34.868684

BibTeX
@article{oliver2000bayesian,
  author = {Nuria Oliver and Barbara Rosario and Alex P. Pentland},
  title = {A {Bayesian} Computer Vision System for Modeling Human Interactions},
  journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence},
  volume = 22,
  number = 8,
  pages = {831--843},
  year = 2000,
  doi = {10.1109/34.868684},
  cites = 1569,
  citesdate = {2026-03-23}
}
★ 1,569 citations

A Bayesian Computer Vision System for Modeling Human Interactions

Nuria Oliver, Barbara Rosario, Alex P. Pentland
IEEE Transactions on Pattern Analysis and Machine Intelligence · 2000

Videos

Examples of interactions recognized by the system: