From the MIT Technology Review:
Back in 1970, the social activist Irina Dunn scribbled a slogan on the back of a toilet cubicle door at the University of Sydney. It said: “A woman needs a man like a fish needs a bicycle.” The phrase went viral and eventually became a famous refrain for the growing feminist movement of the time.
The phrase is also an example of sarcasm. The humor comes from the fact that a fish doesn’t need a bicycle. Most humans have little trouble spotting this. But while various advanced machine learning techniques have helped computers spot other forms of humor, sarcasm still largely eludes them.
These other forms of humor can be spotted by looking for, say, positive verbs associated with negative or undesirable situation. And some researchers have used this approach to look for sarcasm.
But sarcasm is often devoid of sentiment. The phrase above is a good example—it contains no sentiment-bearing words. So a new strategy is clearly needed if computers are ever to spot this kind of joke.