“So it's the story of an American, a French guy and a Belgian...” Stop! There's an extra character in this joke. According to a recent study by Dunbar and colleagues, researchers in experimental psychology, to be insanely funny, a joke must involve the cognitive abilities that allow us to theorize about a state of mind (the other person’s intentions for example). But to make people laugh, be careful not to overload your audience's brains with a joke involving too many characters. How far can we take a joke? Let's take a look.

As humans, we have the ability to understand what others think; this is what we call “theory of mind.” In ordinary communication, we are engaged in a process of reciprocal understanding of the other’s intentions. Paying attention to the emotions and mental states of others, mentalizing them, is a demanding cognitive activity that's limited from a quantitative point of view. This ability can be recursively perpetuated to form a chain of “mentalized intentionality” that can be mentally grasped up to the seventh level. Let's take a concrete example:

1. My wife thinks that... 2. I think my wife thinks that... 3. Peter thinks that I think that my wife thinks that... 4. And so on and so forth until we reach the 7th level!

Understandably, the limits of our ability to process levels of intentionality have to be taken into account for a joke to be funny. But a funny story can involve several characters, creating multiple storylines that can confuse your audience. Which leads us to the question: to maximize the chances of getting a laugh, where should a joke lie on the intentionality mentalization scale?

To answer the question, Dunbar and his team asked a panel of 55 students to evaluate jokes presented on a website (101 funniest jokes of all time). The students were asked to rate the jokes on a scale from 1 (not at all funny) to 4 (very funny). The researchers were thus able to determine each joke's level of intentionality, or the number of mental states involved (a number that is dependent on the number of characters). Most of the jokes involved three to five levels of intentionality. The psychologists also noted a positive correlation between increasing levels of intentionality and the subjective funniness rating of the jokes. Those that were considered to be the funniest had five or six levels of intentionality, and involved a maximum of two characters. Beyond this threshold, the quality of the joke decreases as the number of characters increases.

While other parameters certainly come into play in judging the quality of a joke (simpler and more complex jokes can of course be very funny as well), if you’re planning to start a stand-up career, this research may save you from being a flop!