The professors at Goucher have been spring cleaning, so there are tables full of free textbooks all over the science building. A slave to my compulsive acquisition of codices, I have been leaving school with a heavier backpack every day. Yesterday, I picked up a copy of the 1971 Textbook of Medical Physiology, and began flipping through it during an especially boring session of MCAT review. So, while my friends and colleagues were pretending to be interested in how to write scientific notation, I discovered the joys and foibles of obsolete medical science. I would like to share one particular section which appealed to my Imp of the Perverse. What this means is another non-notebook post-- enjoy them while they last.
"Chapter 50: Somatic Sensations
II. Pain, Visceral Pain, Headache, and Thermal Sensations
[...]
METHODS FOR MEASURING THE PERCEPTION OF PAIN
The intensity of a stimulus necessary to cause pain can be measured in many different ways, but the most used methods have been pricking the skin with a pin at measured pressures, pressing a solid object against a protruding bone with measured force, or heating the skin with measured amounts of heat. The latter method has proved to be especially accurate from a quantitative point of view.
Figure 50-1 illustrates the basic principles of a heat apparatus used for measuring pain threshold. An intense light is focused by a large condenser lens onto a black spot painted on the forehead of the subject, and the heat intensity delivered by the light is controlled by a rheostat. In determining the subject’s threshold for pain, the intensity of the heat is increased in progressive steps, and the length of time required for the forehead to heat sufficiently to elicit pain is recorded for each heat intensity. These data are then plotted in the form of a “strength-duration curve” to express pain threshold, as follows.
[…]
By far, the greatest number of subjects perceive pain when the skin temperature reaches almost exactly 45 °C, and almost everyone perceives pain before 47 °C. In other words, it is almost never true that some persons are unusually sensitive or insensitive to pain. Indeed, measurements in people as widely different as Eskimos, Indians, and whites have shown no significant differences in their threshold for pain. However, different people do react very differently to pain, as is discussed below.
[…]
THE REACTION TO PAIN
Even though the threshold for recognition of pain remains approximately equal from one person to another, the degree to which each one reacts to pain varies tremendously. Stoical persons, such as members of the American Indian race, react to pain far less intensely than do more emotional persons."
There are probably many things to say about this bit of medical arcana, and many questions to ask about the minds behind this research. I imagine that, as children, they enjoyed pursuits that involved ants, a magnifying glass, and the smell of baking chitin in the morning. But my thoughts are perhaps more preoccupied by questions about the kind of individual who decided to strap a series of Caucasians, Indians, and Eskimos into a forehead-burning apparatus and then assessed the quality and intensity of their yelping. Of course, it might seem that the study suggests that the diversity of the world is best represented by two different Native American peoples and "whites." However, this is actually because Asians, Blacks, Latinos, and Polynesian Islanders feel no pain. Or maybe they just don't exist.
Regardless, what it really leaves me with is the mental image of Iron-Eyes Cody with a quarter-sized black spot on his forehead and that single tear trembling on his eyelid. "Stoical" indeed.
(Ironically, both the PSA and the 4th edition of the textbook were from 1971, although whether the pain study appeared in the 1956 first edition is unknown. The forehead-burner seems to have been invented in 1940, so it is possible.)
No comments:
Post a Comment