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Intriguing properties of neural networks

Written for the Research library (claude-opus-5-5) from the paper text. Original — arxiv.org/pdf/1312.6199

Summary

This paper looks at two unexpected behaviours of deep neural networks trained for image classification. First, the authors check whether single hidden units in a high layer carry special meaning. They pick the held-out images that most strongly activate a unit, then do the same for random directions in the activation space. Both sets of images look about equally coherent. This suggests that meaning is spread across the whole representation space rather than tied to individual neurons. Second, the authors find that these networks are surprisingly unstable near correctly classified inputs. An optimisation procedure can find tiny perturbations, nearly invisible to people, that make the model predict the wrong class. They call the results "adversarial examples." These examples often also fool networks with other architectures or hyperparameters, and even networks trained on separate data. A spectral analysis of layer-wise Lipschitz bounds gives a partial explanation for the instability. This was the paper that introduced adversarial examples, and it started the field of research on neural network robustness.

Key points

  • Models tested: fully connected ("FC") and autoencoder-based ("AE") classifiers on MNIST, "AlexNet" on ImageNet, and "QuocNet", an unsupervised network with about 1 billion parameters trained on roughly 10M YouTube images.
  • Images selected by single units and by random linear combinations of units showed similar semantic consistency, on both MNIST and ImageNet. This challenges the idea that each unit captures a separate factor of variation.
  • Adversarial perturbations are found by optimising the input to maximise prediction error. The resulting errors transfer across models, including between MNIST models trained on two disjoint 30,000-image subsets (P1 and P2). Transfer gets weaker in that setting but is still significant.
  • Increasing the perturbation strength (standard deviation from 0.06 to 0.1, about 40% more) made the adversarial examples more effective on other models.
  • Upper Lipschitz bounds per layer, computed with operator norms and a Fourier-based formula for convolutions, show that instability can start in AlexNet's first convolutional layer. The authors suggest penalising these bounds as a form of regularisation.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

Fields: AI & machine learning

Cited by

385 papers of our library cite it (of the 140673 whose bibliographies we read); 40 of them have a page here, 345 not yet.

Cite

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.48550/arxiv.1312.6199 · arXiv 1312.6199

@misc{szegedy2013intriguing,
  title = {{Intriguing properties of neural networks}},
  author = {Szegedy, Christian and Zaremba, Wojciech and Sutskever, Ilya and Bruna, Joan and Erhan, Dumitru and Goodfellow, Ian and Fergus, Rob},
  year = {2013},
  doi = {10.48550/arxiv.1312.6199},
  eprint = {1312.6199},
  archivePrefix = {arXiv},
  url = {https://doi.org/10.48550/arxiv.1312.6199}
}

References

13 references, 2 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

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  13. Matthew D Zeiler and Rob Fergus. Visualizing and understanding convolutional neural networks. arXiv preprint arXiv:1311.2901, 2013. find our card