You know the famous – some would say infamous -- studies done in the 1950s by University of Wisconsin, Madison, psychologist Harry Harlow in which he separated macaque monkeys from their mothers and put them in cages, where they were then given a choice of bonding with surrogate cloth moms or sucking milk from a baby bottle on a wire?

Turns out the monkeys chose the material mamas every time.  What likely sealed the deal was that Harlow had placed a 100-watt light bulb behind each piece of cloth to warm it.

This study, together with work by John Bowlby on attachment theory, led researchers to conclude that there's a link between physical and emotional warmth.  Having learned  about this in college from Bowlby skeptic Jerome Kagan, I was curious about a paper published today in Science that found the following: a person holding a cup of hot coffee was more likely to view others as warmer than if he or she were holding a glass of iced java. The researchers discovered further that volunteers holding something warm were also more more likely to hand over a $1 gift certificate for ice creamto pals than claim a Snapple voucher  for themselves. And if they were clutching something cold? You guessed it: they were more likely to keep the Snapple for themselves. In other words, researchers concluded, holding something warm makes you feel more generous toward others; holding something cold makes you, well, cold and selfish.

I asked  lead study author Lawrence Williams, a business school professor at the University of Colorado, if he and his colleague John Bargh, a Yale professor of psychology, had considered using another kind of beverage. After all, what if it was the caffeine, or another association with the coffee, that was giving people these warm and fuzzy – or frigid --  feelings?

“We chose these as relatively natural beverages that a college student research assistant could have in her hand as she's fulfilling her duties," while running people through an experiment, Williams told me in an E-mail. “So we didn't really consider using other beverages.”

What about other variables? I asked him. Would it matter what color shirt the person in question was wearing? “That's a good question,” he wrote. “I don't know if color translates as easily into interpersonal warmth, but there may be something to that.” He noted that other researchers have found that color can, well, color feelings. “But I would think that red may be associated more with extreme, passionate heat (e.g., a red-hot flame) than warmth per se," Williams speculated.  “There may be some nuances there.”

And if it was a hot day? Holding a hot cup of coffee might not inspire generosity if you’re burning up, I figured. Wrong, according to Williams. Even on a hot day, he wrote, “touching a hot cup will likely activate thoughts and feelings related to interpersonal warmth, even if it simultaneously activates other (either positive or negative) feelings."

Lest you think it's all about drinks, Williams  noted that in a second study (reported in the paper), researchers didn’t use beverages at all, but rather asked participants to hold hot or icy therapeutic pads.

I must admit, I tend to have warm feelings toward anyone who would bring me one of those when I’m in pain. But maybe that’s just because my mother did when I was a kid. My real mother, not a piece of cloth with a light bulb behind it.

Photo by Ahmed Rabea via Flickr