Sarcasm is a cognitive challenge. In order to get the sarcastic sentiment, we can’t simply decode the utterance, or decipher the literal meaning of the sentence. Instead, we have to understand the meaning of the words in their larger social context. For example, if it’s a beautiful day outside – the sun is shining, etc – and somebody states “What a nice day!,” there is no sarcasm; the sentence makes perfect sense. However, if the same statement is uttered on a rainy day, then there is a clear contradiction, which leads to an interpretation of sarcasm. (We typically exaggerate the expression of sarcastic statements, thus making it easier to pick up the verbal/social contradiction.) Psychologists refer to such utterances as an incongruent word-emotion situation.
Given the mental difficulties involved in deciphering sarcasm, it’s interesting to note that the right hemisphere has been repeatedly implicated as an essential component of sarcastic processing. For instance, a 2005 study of patients with lesions to the ventromedial area of the right prefrontal cortex found that they exhibited severe deficits in understanding sarcastic speech, at least when compared to people with left PFC lesions. And then there’s this 2008 study, which showed that people hear sarcasm better when it’s presented to their left ear. (The auditory system, like the visual system, is a case of crossed wires, so that the left ear projects first to your right hemisphere and vice versa.)
What makes this data on sarcasm so surprising is that, until recently, the right hemisphere was thought to play little role in the processing of language. The neuroscientist Roger Sperry, in his 1981 Nobel lecture, summarized the prevailing view of the right hemisphere when he began studying it: “The right hemisphere was not only mute and agraphic, but also dyslexic, word deaf and apraxic, and lacking generally in higher cognitive function.”
But that, of course, is wrong; the right hemisphere is not a mostly useless chunk of tissue. One of my favorite metaphors for our hemispheres comes from Jonathan Schooler, at UCSB. He argues that our hemispheres follow the same information processing strategy as the visual system. “One of the most fundamental features of how the brain sees is that it actually has two different ways of making sense of the world,” he told me recently. “We’ve got one visual system that’s interested in fine-grained details and clarity. That’s the system associated with the fovea and cones in the retina, which we use to perceive things like words on the page. But we’ve also got a more coarse-grained system too, which allows us to quickly grasp an entire scene, or to see some movement out of the corner of our eye.” According to this metaphor, the left hemisphere excels at the fine-grained and literal, while the right hemisphere is better at coarse-grained analysis, allowing us to make sense of things within their context.
Reality, in other words, is so richly complex that the brain has to process it in two different ways at the same time. We need to see the trees, but we also have to remember the forest. Of course, these implicit and connotative connections – all the stuff that’s not in the dictionary definition – are what make language such a richly expressive tool. When you read a poem, or hear some emotionally charged words, or laugh at the punch line of a joke, you are relying, in large part, on the right hemisphere. Sarcasm, of course, is a perfect example of speech that requires a contextual understanding. The only way to know if someone is being sarcastic is to look around. The incongruity isn’t in the words – it’s in the world.