Androids may not dream of electric sheep, but some crack jokes about horses and cows.

What’s new: Meena, a 2.6-billion parameter chatbot developed by Google Brain, showed impressive conversational ability, discussing a variety of topics. In one exchange, it unexpectedly sprinkled in some barnyard humor: It commented that “horses go to Hayvard,” not Harvard. The phrase didn’t appear in the training data, but the word Hayvard did appear once, a pun after a mention of horses, according to a company spokesperson. The bot followed up with another farm-animal pun, noting that its interlocutor tried “to steer [the conversation] elsewhere.” The first-ever AI-generated dad joke?

How it works: Google engineer Daniel De Freitas Adiwardana told us how, in training on 341 gigabytes of public social media conversation, Meena might have developed a sense of humor. Straight from the horse’s mouth, as it were:

  • “At a high level, when the model is training, it’s required to try to predict a lot of sequences of words, all at the same time. So it’s forced to come up with strategies that solve all these prediction problems at once.
  • “In the beginning of the convergence, when the perplexity is still high, these greedy choices lead to doing things like repeating common words, like ‘the the the the.’ It lowers its loss function value that way.
  • “Over time, it learns new ways to cheat that lower the loss even further, like repeating what the other person said (‘do you like pizza?’ > ‘Do you like pizza?’). Then it makes a twist on that, using repetitions (‘do you like pizza?’ > ‘I like pizza, I like pizza’), contradictions (‘do you like pizza?’ > ‘I like pizza, I don’t like pizza’), and/or added conjunctions (‘do you like pizza?’ > ‘I like pizza, but I don’t like pizza’).
  • “Eventually it gets to something that is still cheating, in a sense, but much more sensible, like (‘do you like pizza?’ > ‘I like pizza, but I try not to eat it everyday’). Maybe no one said that sentence exactly, but it sort of looks like something a lot of people said.
  • “The empirical and hand-wavy moral of the story is that, as it gets harder to make learning progress, the cheating gets more sophisticated. One of possibly many views is that the cow and horse jokes are just a pretty sophisticated form of cheating, which many people would start to feel comfortable calling generalization.”

Behind the news: Efforts to give AI a sense of humor have met with limited success. One of the most impressive is a jokebot that writes captions for cartoons in The New Yorker. That model separates the normal aspects of a picture (for instance, a salesman showing off a new car) from oddball elements (the car has cat-like legs), then writes a caption based on the contrast. But even its best efforts (“just listen to that baby purr”) are more intriguing — because they were written by a computer — than side-splitting.

Why it matters: Humor affects us in deep and subtle ways. A Tina Fey-level bot may be out of reach, but a funny bone would be a valuable feature in an empathetic AI.

We’re thinking: We’d like to see a football game between Hayvard and Dartmooth.

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