When a 12-year-old’s mother asks him “How many times do I have to tell you to stop?” he will understand that the answer, if any is required, had better not include a number.

But that insight requires a sophisticated understanding of ironic language that develops long after fluent speech. At what age do children begin to sense the meaning of such a question, and to what degree can they respond appropriately to other kinds of irony?

In laboratory research on the subject, children demonstrate almost no comprehension of ironic speech before they are 6 years old, and little before they are 10 or 11. When asked, younger children generally interpret rhetorical questions as literal, deliberate exaggeration as a mistake and sarcasm as a lie.

But there has been little research on the subject outside the laboratory. So a group of Canadian researchers set out to record parents and children at home as they used four types of ironic language: sarcasm, hyperbole, understatement and rhetorical questions. It turns out that very young children can understand and even use ironic speech, even if they cannot describe what they have done to a researcher.