Cohen's study was actually an attempt to determine how much protection social support provides against stress and the physical vulnerability it creates, in this case to colds and flu. As expected, the researchers found that people who perceive that they have strong social support networks enjoyed a degree of "buffering" against stress and those physical ailments. When they separated out hugging's role in that protection, they were able to assign it "32 percent of the attenuating effect of support."
"The study suggests that people who have relationships that are intimate enough that they're getting hugged are protected, and that hugging is one indicator of that," Cohen said in an interview.
Before you go embracing strangers on the street in violation of doctors' warnings to limit touching during cold and flu season, it's important to remember that the study is complicated. The main thing to know is that Cohen's team assessed the number of hugs and how much personal interaction people experienced during a two-week period before they were exposed to viruses. The average person in the study said he or she received at least one hug on 68 percent of the 14 days. Only 20 percent of them were married.
Also, the researchers were measuring support's protection against chronic stress — such as the long-term effects of a bad marriage — not the short-term stress of holiday hassles.
That said, when they controlled for numerous other variables — age, gender, extroversion, neuroticism and agreeability, to name a few — they found clear associations between hugging and protection from the viruses.
Psychologists have long known that perceived social support can protect against illness and psychological distress, such as depression and anxiety, brought on by stress. But protection against disease has mostly been tested in the lab, by measuring physiological changes that occur when people respond to non-sexual touching.
Cohen's team looked at interviews his team conducted daily for 14 days about social support and hugging during two previous studies, one from 2000 to 2004 and another from 2007 to 2011. Then 406 people, all of them healthy, were quarantined in hotels and given nasal drops containing cold and flu virus. Researchers tested them for symptoms.
How? Well they collected the tissues they used to blow their noses in plastic bags and weighed them for mucus content. They also injected a dye in their upper respiratory tract to see how long it took for them to clear mucus from their nasal tracts. And they drew blood to measure their baseline levels of antibodies to colds and flu.
In the end, they determined that people who believed they had little social support and were living with a lot of stress were more likely to be infected — meaning the virus replicated itself in their systems. For people who said they had good social support or were receiving many hugs, the frequency of tension and conflict in their lives had no impact on infection.
The data shows that "nonsexual physical touch, such as hugging, is a means of conveying empathy, caring and reassurance and that this implicit communication of affection and concern contributes importantly to the protective influence of perceived support against the pathogenic effects of stress," the researchers wrote.
"A possible explanation for the buffering effect of being hugged is that hugs might be exchanged between individuals involved in a tension/conflict either as a means of resolving that conflict or as a counter to associated emotional after-effects," they concluded. "In predicting infection, we found that hugs on non-tension days were at least as important as those reported on tension days, thus suggesting that the buffering effects of hugging were not limited to hugs given as an immediate (same day) response to tension/conflict.
"These findings suggest that those who regularly receive hugs are more protected than those who do not."