Researchers had 40 people looked at head shots of patients, all of whom had shoulder problems, paired with adjectives that were positive, neutral, or negative ("honest," "reserved," or "arrogant," for example). They then watched clips of the patients undergoing physiological examination, in which the patients manifested no pain, moderate pain, or severe pain.
The observers then rated the pain's intensity by marking a spot on a visual scale 100 millimeters long.
In the case of high-intensity pain, the participants rated the pain of "disliked" patients as lower than that of the other patients—on the order of 7 points lower, on the 100-point scale. There was no difference on the moderate pain. (To explain the difference, the researchers suggested that the relatively extreme grimaces and grunts that intense pain inspires might cause distinctive reactions: You might think, for example, that someone you dislike is being overly dramatic or self-centered.)
This layman's conclusion was that you should be nice to your nurse. But one author cautioned that the study involved ordinary observers, not health-care professionals, so it would be unfair to assume their judgment is clouded by your likeability—or lack of same.
Source: "When You Dislike Patients, Pain Is Taken Less Seriously," Lies De Ruddere, and six other authors, Pain (October)