Experimental hypothermia and cold perception.

Twelve subjects clothed in flotation suits were immersed in 10 degrees C cold water and their surface temperatures at the back and groin, as well as core temperatures, were continuously monitored. Subjects were unable to reliably assess how cold they were, with the highest correlation observed between perceived temperature and actual temperature reaching only 0.51. This was felt to be partially due to the uneven distribution of surface temperatures seen in this experiment and in most cold water immersions. Rapid cooling in cold water also produced the perceptual phenomenon of "overshooting" previously observed in cold air studies, characterized by sudden temperature drops being perceived as cold sensations of greater magnitude. The results suggest that subjects who are rapidly cooled in water may have considerable difficulty separating feelings of cold from feelings of pain and discomfort, which can have serious implications in survival situations and highlights the subjective and highly variable nature of cold perception. Perceived cold sensation may be a very poor, and possibly dangerous, predictor in cold water immersion situations.