Thursday, March 4, 2021

Multimodal Neurons in Artificial Neural Networks

OpenAI (via Hacker News, paper):

We’ve discovered neurons in CLIP that respond to the same concept whether presented literally, symbolically, or conceptually. This may explain CLIP’s accuracy in classifying surprising visual renditions of concepts, and is also an important step toward understanding the associations and biases that CLIP and similar models learn.


Through a series of carefully-constructed experiments, we demonstrate that we can exploit this reductive behavior to fool the model into making absurd classifications. We have observed that the excitations of the neurons in CLIP are often controllable by its response to images of text, providing a simple vector of attacking the model.

The finance neuron, for example, responds to images of piggy banks, but also responds to the string “$$$”. By forcing the finance neuron to fire, we can fool our model into classifying a dog as a piggy bank.


We refer to these attacks as typographic attacks. We believe attacks such as those described above are far from simply an academic concern. By exploiting the model’s ability to read text robustly, we find that even photographs of hand-written text can often fool the model. Like the Adversarial Patch, this attack works in the wild; but unlike such attacks, it requires no more technology than pen and paper.


When we put a label saying “iPod” on this Granny Smith apple, the model erroneously classifies it as an iPod in the zero-shot setting.

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