A robot walks into a bar. It goes CLANG.

Alexa and Siri can tell jokes mined from a humour database, but they don鈥檛 get them.

Linguists and computer scientists say this is something to consider on April Fools鈥� Day: Humor is what makes humans special. When people try to teach machines what鈥檚 funny, the results are at times laughable but not in the way intended.

鈥淎rtificial intelligence will never get jokes like humans do,鈥� said Kiki Hempelmann, a computational linguist who studies humour at Texas A&M University-Commerce. 鈥淚n themselves, they have no need for humour. They miss completely context.鈥�

And when it comes to humour, the people who study it 鈥� sometimes until all laughs are beaten out of it 鈥� say context is key. Even expert linguists have trouble explaining humour, said Tristan Miller, a computer scientist and linguist at Darmstadt University of Technology in Germany.

鈥淐reative language 鈥� and humour in particular 鈥� is one of the hardest areas for computational intelligence to grasp,鈥� said Miller, who has analyzed more than 10,000 puns and called it torture. 鈥淚t鈥檚 because it relies so much on real-world knowledge 鈥� background knowledge and commonsense knowledge. A computer doesn鈥檛 have these real-world experiences to draw on. It only knows what you tell it and what it draws from.鈥�

Allison Bishop , a Columbia University computer scientist who also performs stand-up comedy, said computer learning looks for patterns, but comedy thrives on things hovering close to a pattern and veering off just a bit to be funny and edgy.

Humour, she said, 鈥渉as to skate the edge of being cohesive enough and surprising enough.鈥�

For comedians that鈥檚 job security. Bishop said her parents were happy when her brother became a full-time comedy writer because it meant he wouldn鈥檛 be replaced by a machine.

鈥淚 like to believe that there is something very innately human about what makes something funny,鈥� Bishop said.

Oregon State University computer scientist Heather Knight created the comedy-performing robot Ginger to help her design machines that better interact with 鈥� and especially respond to 鈥� humans. She said it turns out people most appreciate a robot鈥檚 self-effacing humour.

Ginger, which uses human-written jokes and stories, does a bit about Shakespeare and machines, asking, 鈥淚f you prick me in my battery pack, do I not bleed alkaline fluid?鈥� in a reference to 鈥淭he Merchant of Venice.鈥�

Humour and artificial intelligence is a growing field for academics.

Some computers can generate and understand puns 鈥� the most basic humour 鈥� without help from humans because puns are based on different meanings of similar-sounding words. But they fall down after that, said Purdue University computer scientist Julia Rayz.

鈥淭hey get them 鈥� sort of,鈥� Rayz said. 鈥淓ven if we look at puns, most of the puns require huge amounts of background.鈥�

Still, with puns there is something mathematical that computers can grasp, Bishop said.

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Rayz has spent 15 years trying to get computers to understand humour, and at times the results were, well, laughable. She recalled a time she gave the computer two different groups of sentences. Some were jokes. Some were not. The computer classified something as a joke that people thought wasn鈥檛 a joke. When Rayz asked the computer why it thought it was a joke, its answer made sense technically. But the material still wasn鈥檛 funny, nor memorable, she said.

IBM has created artificial intelligence that beat opponents in chess and 鈥淛eopardy!鈥� Its latest attempt, Project Debater , is more difficult because it is based on language and aims to win structured arguments with people, said principal investigator Noam Slonim, a former comedy writer for an Israeli version 鈥淪aturday Night Live.鈥�

Slonim put humour into the programming, figuring that an occasional one-liner could help in a debate. But it backfired during initial tests when the system made jokes at the wrong time or in the wrong way. Now, Project Debater is limited to one attempt at humour per debate, and that humour is often self-effacing.

鈥淲e know that humour 鈥� at least good humour 鈥� relies on nuance and on timing,鈥� Slonim said. 鈥淎nd these are very hard to decipher by an automatic system.鈥�

That鈥檚 why humour may be key in future Turing Tests 鈥� the ultimate test of machine intelligence, which is to see if an independent evaluator can tell if it is interacting with a person or computer, Slonim said.

There鈥檚 still 鈥渁 very significant gap between what machines can do and what humans are doing,鈥� both in language and humour, Slonim said.

There are good reasons to have artificial intelligence try to learn to get humour, Darmstadt University鈥檚 Miller said. It makes machines more relatable, especially if you can get them to understand sarcasm. That also may aid with automated translations of different languages, he said.

Texas A&M鈥檚 Hempelmann isn鈥檛 so sure that鈥檚 a good idea.

鈥淭eaching AI systems humour is dangerous because they may find it where it isn鈥檛 and they may use it where it鈥檚 inappropriate,鈥� Hempelmann said. 鈥淢aybe bad AI will start killing people because it thinks it is funny.鈥�

Comedian and computer scientist Bishop does have a joke about artificial intelligence: She says she agrees with all the experts warning us that someday AI is going to surpass human intelligence.

鈥淚 don鈥檛 think it鈥檚 because AI is getting smarter,鈥� Bishop jokes, then she adds: 鈥淚f the AI gets that, I think we have a problem.鈥�

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Seth Borenstein, The Associated Press

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