Temperature regulation during fever: change of set point or change of gain? A tentative answer from a behavioural study in man.

1. Four subjects were immersed in a stirred water-bath maintained at either 30 or 40 degrees C. The left hand was placed out of the bath in a glove receiving water at a temperature selected by the subject as most pleasurable. Experiments were conducted during the euthermic state and during either spontaneous or induced fever.2. The results of control experiments confirm a previous observation using the same method, that preferred hand skin temperature was a linear function of internal temperature but also indicated an influence by mean skin temperature.3. The general pattern of response during fever was identical to that when fever was absent except that the regulated steady state internal temperature was higher and the slopes of preferred temperature plotted against internal temperature were steeper.4. The results seem to support the concept of a change in set point rather than that of a change in the gain of the thermoregulatory processes during fever.