The 55-year-old professor at the University of Montreal, who sports bushy gray hair and eyebrows, says deep learning works well in idealized situations but won’t come close to replicating human intelligence without being able to reason about causal relationships. “It’s a big thing to integrate [causality] into AI,” Bengio says. “Current approaches to machine learning assume that the trained AI system will be applied on the same kind of data as the training data. In real life it is often not the case.”
Machine learning systems including deep learning are highly specific, trained for a particular task, like recognizing cats in images, or spoken commands in audio. Since bursting onto the scene around 2012, deep learning has demonstrated a particularly impressive ability to recognize patterns in data; it’s been put to many practical uses, from spotting signs of cancer in medical scans to uncovering fraud in financial data.
But deep learning is fundamentally blind to cause and effect. Unlike a real doctor, a deep learning algorithm cannot explain why a particular image may suggest disease. This means deep learning must be used cautiously in critical situations.
Understanding cause and effect would make existing AI systems smarter and more efficient. A robot that understands that dropping things causes them to break would not need to toss dozens of vases onto the floor to see what happens to them.
Bengio says the analogy extends to self driving cars. “Humans don't need to live through many examples of accidents to drive prudently,” he says. They can just imagine accidents, “in order to prepare mentally if it did actually happen.”
The question is how to give AI systems this ability.
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At his research lab, Bengio is working on a version of deep learning capable of recognizing simple cause-and-effect relationships. He and colleagues recently posted a research paper outlining the approach. They used a dataset that maps causal relationships between real-world phenomena, such as smoking and lung cancer, in terms of probabilities. They also generated synthetic datasets of causal relationships.
The algorithm in the paper essentially forms a hypothesis about which variables are causally related, and then tests how changes to different variables fit the theory. The fact that smoking is not only related to cancer but actually causes it, for instance, should still be apparent even if cancer is correlated with other factors, such as hospital visits.
The favorable results in cells and mice were a pleasant surprise; he’d expected the AI-generated molecules would require more tweaks and rounds of computations before they found one with potential.“It’s cool to see AI trained to think a little bit like how a medicinal chemist thinks,” says Adam Renslo, a professor of chemical biology at the University of California-San Francisco who also wasn’t involved in the research.
A robot might eventually use this approach to form a hypothesis about what happens when it drops something, and then confirm its hunch when it sees several things smash to the floor.Bengio has already transformed AI once. Over the past several decades, he helped develop the ideas and engineering techniques that unleashed the potential of deep learning, together with this year’s other Turing Award recipients: Geoffrey Hinton, of the University of Toronto and Google, and Yann LeCun, who works at NYU and Facebook.Deep learning uses artificial neural networks to mathematically approximate the way human neurons and synapses learn by forming and strengthening connections. Training data, such as images or audio, are fed to a neural network, which is gradually adjusted until it responds in the correct way. A deep learning program can be trained to recognize objects in photographs with high accuracy, providing it sees lots of training images and is given plenty of computing power.