On our drive home from a family vacation in the mountains, my husband and I anticipated some challenges with our five small children, including boredom, irritability, and repetitions of that age-old question, “Are we there yet?”. We did not, however, anticipate the torrent of vomit that spewed from my daughter when she erupted with motion sickness.  The contents of her stomach streamed over every person and filled every crevice in our tightly-packed minivan, and no amount of wiping, scrubbing, or “airing out” could rid our vehicle of the stench. It was frustrating, disgusting, and downright offensive. It was decidedly NOT funny…at least not at the time.
As the noxious odor faded from the car in the ensuing days, we were able to see the humor in the situation and in fact took pleasure regaling our friends and family with the tale. Now, years later, the episode is just one of many stories about journeys with our kids — no longer wickedly disgusting but also not as vividly funny as it was shortly afterward.
New research by Peter McGraw and colleagues suggests that our vomit encounter parallels what many people experience in unpleasant or harrowing situations. It can be difficult and even inappropriate to laugh in the face of adversity, but it seems that time can help transform a calamity into a comedy. This transformation is not all that surprising, as Mark Twain recognized more than 100 years ago that, “humor is tragedy plus time.” But McGraw and colleagues propose that disasters do not merely get funnier over time; rather, they get more humorous with the passage of some time, and then tend to lose their comedic value as even more time elapses. Thus, time creates a comedic “sweet spot” in which an experience, episode or event is maximally humorous.
Support for this idea comes from a longitudinal study examining reactions to jokes about Hurricane Sandy. Participants were asked to evaluate mock tweets about the hurricane at ten different time points that spanned from the day before the hurricane hit the Northeastern United States to roughly   14 weeks after it made landfall. At each time point, independent samples of 100 participants read three different tweets about the storm from a twitter account titled @AHurricanSandy (e.g., “JUS BLEW DA ROOF OFF A OLIVE GARDEN FREE BREADSTICKS 4 EVERYONE”). Participants reported the extent to which they found the tweets offensive or humorous.
As you might expect, humor ratings for the mock tweets were lowest and offensiveness ratings were highest in the two weeks after Sandy hit, when the tragic nature of the event became evident with reports of damage, destruction, injury and death. Gradually, though, humor ratings for the tweets increased and then peaked about a month after the event, and at the same time the offensiveness ratings dropped. Apparently the temporal distance from the destruction created a window in which it was acceptable, even desirable, to make light of the event. Yet the jokes about the hurricane also seemed to have an expiration date, as humor ratings significantly declined two months after the event, and three months out the jokes were no more amusing than they were the day after the hurricane hit.
McGraw and colleagues postulate that this temporal pattern not only gives important insight about when a joke will be amusing, but also why it is amusing. They believe that humor derives from a “benign violation” that occurs when a stimulus is physically or psychologically threatening and simultaneously benign. While a “harmless threat” may seem paradoxical, consider the familiar scenario of witnessing a friend or colleague slip and fall. At first the event may induce concern, but if the colleague is unharmed the mishap is likely to evoke laughter. According to the benign violation theory, humor requires just the right dose of threat or tension — too much threat and the situation is not seen as benign; however, too little threat renders the situation mundane or boring.
By this account, we are able to appreciate the humor in tragic or devastating events after some delay because time reduces the severity of the violation. Time puts a psychological distance between us and the event, thereby creating the ideal balance of threat and safety in the recipe for humor. With a relatively short passage of time, the episode captures the perfect combination of violation and security, and the potential for humor is optimal. As additional time elapses, however, the violation diminishes to the point that the event is too benign or irrelevant to make us laugh.
Time is not the only factor that gives us the perspective we need to appreciate humor. Related studies show that psychological separation can be created by physical space (e.g., near versus far), social relations (e.g., us versus them), and even dimensions of reality (e.g., fact versus fiction). Projectile vomit is more comical, for example, if it occurs in someone else's car instead of our own, if it afflicts a stranger rather than oneself, or if it happens in a movie scene rather than real life. As with time, though, the distance created by these other dimensions must be just right. Too much distance (e.g., a joke about heat and humidity in the middle of an ice storm), and the laughs turn to groans.
Understanding when and why a scenario is funny is not simply useful for late night television hosts and stand-up comics. Humor plays a powerful and important role in the human experience. Humor helps people cope with pain and tragedy, reduces social conflict, and softens criticism. Humor also increases personal appeal in that funny people are perceived as more intelligent, likeable, and sexually attractive. Indeed, tell a bad joke and you may be the subject of ridicule and social isolation. Thus humor serves not only as a tool for coping with difficult life events, but also as an avenue for social acceptance and well-being. The work of McGraw and colleagues suggests that when it comes to humor, as with so many other things in life, timing is everything.

Are you a scientist who specializes in neuroscience, cognitive science, or psychology? And have you read a recent peer-reviewed paper that you would like to write about? Please send suggestions to Mind Matters editor Gareth Cook, a Pulitzer prize-winning journalist and regular contributor to NewYorker.com. Gareth is also the series editor of Best American Infographics, and can be reached at garethideas AT gmail.com or Twitter @garethideas.