The poets were right about the chill of isolation and rejection — more, perhaps, than even they knew: when a person feels lonely or is being excluded by others, his or her skin literally becomes colder.

For the past several years, our lab has been studying just how people respond to exclusion and other social interactions. In one recentexperiment, published earlier this year in the journal Acta Psychologica, we asked dozens of students to participate in a simulated ball-tossing game with computer-generated cartoonlike figures called avatars. While they played, we measured their skin temperature 24 times over the course of the experiment with a device most commonly used for industrial coolers (accurate to within three-hundredths of a degree Celsius).

Research by the Purdue University psychologist Kip Williams, who programs these avatars to refrain from tossing the ball to certain human subjects, has shown that people feel bad when left out. But perhaps more striking is what happens to a person’s body temperature in such scenarios. By the end of our imaginary game of catch, finger temperatures of those whom the avatars excluded dropped by an average 0.378 degrees. (Those who were included experienced no change in temperature.)