I can’t remember the last time I had a good, long cry. Well, that’s not entirely true. I was bawling my eyes out just the other night at the inevitable climax to the movie Marley & Me. But with the possible exception of my eggshell-fragile Achilles’ heel for old and dying dogs, I’ve never been much of a weeper. I’ve always wanted to be, though. At times I’ve even felt a little guilty when tears seemed appropriate but I couldn’t muster any up. Even onions let me down when I once tried to use them to jumpstart a liquid catharsis.

But perhaps crying isn’t all it’s cracked up to be anyway. University of South Florida psychologist Jonathan Rottenberg and his colleagues Lauren Bylsma and Ad J.J.M. Vingerhoets have argued that, contrary to popular belief, there’s actually a surprising absence of empirical data to support the view that crying is beneficial. In fact, there’s even some evidence that--for some people at least--crying could do more harm than good. In a 2008 issue of Current Directions in Psychological Science, the authors review all the available evidence to date on crying-based research. They begin by questioning the rather dubious claims made by psychodynamic-minded theorists over the years. These are typically of the “it’s good to get it out of your system” variety, with “it” being those dark, repressive thoughts that clog up your brain or ravage your healthy psychological functioning. In her book Seeing Through Tears: Crying and Attachment (Routledge, 2005), Judith Kay Nelson reports that without any science on the subject to back up their prescriptions for shedding liberal amounts of tears, over two-thirds of mental health practitioners actively promote crying as a therapy tool.

This general sentiment about the salubrious qualities of sobbing are echoed in our common-sense views too. In survey reports where researchers asked people whether having a good cry made them feel better, respondents overwhelmingly say it has. But the curious thing, Rottenberg and coauthors point out, is that in laboratory-based psychology experiments where crying is elicited by a sad stimulus (such as a clip from Marley & Me, which will do nicely if you have a sliver of a heart), participants who cry actually report feeling worse than those who watch the same scene without crying.

There are obvious reasons why the retrospective self-reports of crying episodes fail to line up neatly with findings from controlled experiments on crying. For one, crying in response to a tearjerker in a sterile laboratory environment after some stranger attaches physiological equipment to you and then takes notes in the other room isn’t exactly the same as crying into a pillow in your own bedroom. Negative social emotions such as embarrassment might cancel out any possible positive feelings.

It’s a classic dilemma in emotion research--how does one produce genuine, unadulterated affect in a rigorously controlled laboratory setting so that the findings are “ecologically valid” (that is to say, true to life)? Experimental psychologists can’t very well go around making their participants cry by being mean to them or telling them that their dog just died. Well not ethically, anyway. So any tears conjured up in the lab are probably going to be somewhat contrived, sort of like a doctor striking your knee with a rubber mallet rather than you giving a genuine kick. There’s also the issue of individual differences. What’s painfully sad for one person isn’t necessarily so for another; thus the comparative benefits of crying versus not crying aren’t necessarily equivalent across the participant sample.

Wary of the limitations of experimental design in researching crying behavior, the authors describe a recent study in which they analyzed over 3000 detailed reports of natural sobs. Consistent with the earlier survey findings, participants overall reported positive mood changes after crying. When they looked at the data more closely, however, the authors discovered that a third of the respondents reported no mood changes at all, and a tenth of them reported feeling even worse after crying. “Importantly,” Rottenberg and his colleagues write, “variation in social-environmental factors tracked the mood benefits of crying.” Specifically:

Criers who received social support during their crying episode were more likely to report mood benefits than were criers who did not report receiving social support. Likewise, mood benefits were more likely when the precipitating events of a crying episode had been resolved than they were when events were unresolved. Finally, criers who reported experiencing negative social emotions like shame and embarrassment were less likely to report mood benefits.

To me, the social aspects of crying--including how such behavior often serves a solicitous role in prompting responses by onlookers--are incredibly fascinating. And the social dynamic starts early. According to evolutionary psychologist Nick Thompson from Clark University, the acoustic characteristics of distress cries in infants are specially designed to goad caregivers into responding quickly. The proposed adaptation involves a rapid, gasping inhalation between bursts of loud crying. Thompson believes that this ‘pitch-to-cry' ratio deceives parents into thinking that the baby might be suffering from some sort of respiratory distress, which in turn triggers a prompt caregiving response. The baby of course, certainly isn’t manipulating the parent consciously; nor is the parent always fooled. But the idea is that natural selection favored those babies whose cries mimicked choking sounds because adults were generally more vigilant to those babies’ needs. As a consequence, these babies (who were our ancestors) would have been less likely to find themselves left alone or with strangers for long periods of time--and therefore less likely to befall genuine harm.

There appears to be a typology of adult crying, too--say, the lonely, subdued weeping where your shoulders go up and down; the occasions where your eyes silently brim over with giant teardrops that race down your cheeks; histrionic, paroxysmal sobs that aren’t altogether unlike the respiratory distress patterns of infants’ cries. Tears generated by physical pain seem different altogether. As far as I know, evolutionary psychologists haven’t looked at these adult crying types in any formal theoretical way, although Nelson does describe a few possible functional differences in her book.

Rottenberg and his coauthors also point out that nearly all of the research on crying to date has centered on negative events. But sadness isn’t the only thing that provokes tears. One of the things I remember vividly about my mother’s face was how her eyes would always fill up with tears whenever she felt genuinely loved. (Needless to say, this sort of thing would always make me want to hug her.) Such “tears of joy”--the ones that flow liberally at events such as weddings and births--betray deep, genuine emotions. Since our ancestors were vulnerable to deception, I suspect that crying probably evolved as a sort of hard-to-fake communicative signal. Comparative psychologists have long suspected that, compared to other social species, human beings are uniquely skilled at manipulation. The fact that we are the only ones who actually shed tears from emotions may shed some important light on our Machiavellian past. Tears would have been a reliable indication that the other party actually felt as sincerely as they said they did.

So as the authors wisely sum up in their review, the question of whether crying is beneficial must be asked in a new way: “Under what conditions and for whom is crying likely to be beneficial?” Now go on, say something to make me cry, I challenge you. Maybe it’ll be good for me, maybe it won’t. But go easy on me--I’m very sensitive. And for God’s sake, leave my dogs out of it.

In this column presented by Scientific American Mind magazine, research psychologist Jesse Bering of Queen's University Belfast ponders some of the more obscure aspects of everyday human behavior. Ever wonder why yawning is contagious, why we point with our index fingers instead of our thumbs or whether being breastfed as an infant influences your sexual preferences as an adult? Get a closer look at the latest data as “Bering in Mind” tackles these and other quirky questions about human nature. Sign up for the RSS feed or friend Dr. Bering on Facebook and never miss an installment again.