"Well, that's just great."

"Well, that's just great."

Quick, what does that sentence mean? Is the speaker acknowledging some good news, celebrating a joyful event that just took place? Do we take the sentence at face value? Or is it possible that the speaker really means something quite different, maybe even the opposite? Perhaps his pleasure is not genuine.

Well, the fact is we don’t know. The words are ambiguous. The speaker’s comment could be kind and authentic: Imagine his daughter has just announced that she made the school honor roll for the first time. But the speaker could just as well be stuck in rush-hour traffic, late for an important meeting. His comment in that case is probably not genuine at all, but sarcastic.

How can we tell which is which? How as listeners do we recognize and comprehend irony? And what makes us use sarcasm and irony in the first place, when we could just as easily be literal and unambiguous? Communication is risky enough without deliberately muddling things with hidden layers of meaning. What social purpose could such vagueness possibly serve?

Psychologists are very interested both in how we use ironic language, and how we see it for what it is. And there are lots of ideas. Some argue that ironic language is the language of failed expectations; it’s a fact of the human condition that things often don’t always turn out as planned, and language needs to capture and highlight that ironic sense of life. But when and how does that sense of life emerge, and when do we develop the social competence to recognize it?

One way to approach these questions is to look at language comprehension in children. Children have no life experiences to speak of, so it would seem that they should be innocent of life’s ironies. They should take every sentence they hear literally, unless they’re given some reason not to. So, to stick with the same example: If someone says, “Well, that’s just great,” kids should simply believe it. They shouldn’t be expected to probe for deeper meaning.

But do they? Psychologist Penny Pexman of the University of Calgary, Canada, decided to explore this question in the laboratory, to see just how quick and efficient kids really are at processing irony and sarcasm. She wanted to see how early in life this cognitive skill emerges. She also wanted to see if indeed kids go through a two-step process every time they are confronted with irony—taking the literal meaning first, then perceiving the hidden meaning as an afterthought.

It’s hard to study kids’ minds, especially the six- to ten-year-old minds in Pexman’s studies. She couldn’t really rely on the kids to report on their own thinking, so she had to devise special methods to probe their perceptions. Here’s an example of what she did. In one experiment, she trained kids to associate niceness with a smiling yellow duck, and meanness with a snarling gray shark. Then the kids watched puppet shows, in which the puppets made both sarcastic and literal remarks. Rather than ask they kids to interpret the remarks, she tracked their eye gaze, to see if they shifted their attention ever so slightly toward the shark or the duck after a particular remark.

The results, reported in the August issue of the journal Current Directions in Psychological Science, were intriguing. If kids were indeed processing every sentence as literally true to begin with, then their eyes would reveal that: That is, they would look automatically at the duck upon hearing, “Well, that’s just great.” But they didn’t. When that sentence was used ironically, their eyes went immediately to the mean shark. The irony required no laborious crunching: They processed the insincerity as rapidly as they processed the basic meaning of the words.

So ironic sensibility appears to be deep-wired into the neurons. But using and understanding irony also requires social intelligence. Both children and adults need hints that a comment is ironic as opposed to literal. These hints come in the form of facial expression, tone of voice, knowledge of the speaker’s personality, and so forth. All of these social cues are processed instantaneously, and integrated into a reliable sense of what's going on in another's head, his beliefs and intentions. Children with autism have difficulty doing this—that is, “theorizing” about what others are thinking and feeling. Interestingly, some autistic children also have difficulty appreciating irony and sarcasm, suggesting that the same brain abnormality may be linked to both deficits.

Pexman’s puppet experiments have revealed a fascinating subtlety about children’s emerging ironic sensibilities. She found that while even kids as young as six understand ironic criticism, they do not seem to "get" ironic praise. For example, if a young child misses a soccer goal, he has no trouble knowing that “hey, nice shot” is insincere and mean-spirited. But if he scores a difficult shot and a teammate yells “hey, lousy shot, man,” that’s a lot harder. It doesn't compute automatically. In other words, children appreciate hurtful irony but not warm irony.

Why would this be? Pexman believes it’s because most people have a general expectation that others will be nice to them, not mean; ironic language calls attention to the unexpected meanness. Which seems to suggest that kids develop a sardonic sense of life's travails very early on. Well, that’s just great.

For more insights into the quirks of human nature, visit “We’re Only Human . . .” at www.psychologicalscience.org/onlyhuman. Selections from the weblog also appear in the magazine Scientific American Mind and at the website www.sciam.com.