Relationship between noxious cold stimuli and the magnitude of pain sensation in man

Nine healthy subjects received noxious cold stimulations at 20, 15, 10, 5 and 0 degrees C on the thenar eminence of both hands. Each stimulus lasted 30 sec. At the end of the stimulus, subject estimated pain intensity on a scale graduated from 0 (no pain) to 10 (intolerable pain). The results showed that the intensity of cold pain and that of the stimulus are linearly correlated (Spearman test P less than 0.001). Cold pain obeys Stevens' law with an exponent equal to one.