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Squeezing Testicles Causes Finger Shrinkage, 1935

E.A. Carmichael
The scene: London, 1935. A man in his mid-twenties sits in a comfortable chair in the middle of a hospital room. His eyes are tightly closed. His elbows are supported by the armrests. Several fingers of his right hand are enclosed in glass devices resembling test tubes, connected by plastic tubing to a machine. An older man wearing a white lab coat creeps up behind him, careful not to make any noise. The older man walks around in front of the sitting man, looks closely at him to determine that his eyes are shut, then reaches down between the other man's legs and grabs and roughly squeezes the testicles. The younger man gasps.

The above experiment, conducted by the brain specialist Edward Carmichael, was designed to test the reaction of the sympathetic nervous system to sudden shocks. Carmichael hypothesized that such shocks would trigger a vasomotor response. That is, the sympathetic system, which controls the body's "fight or flight response," would rapidly constrict blood vessels.

Carmichael measured the vasomotor response by means of a device that could sense minute changes in the width of fingers — since constricting blood vessels would reduce blood flow to the digits causing them to shrink slightly. This device consisted of a glass container placed around the fingers, connected to a machine that could detect subtle variations in air volume.

Carmichael had his subjects sit in a room in which absolute silence was maintained. The subjects had to keep their eyes tightly closed. Carmichael then exposed them to a series of shocks, all the while recording the expansion and contraction of their fingers.

The shocks took a variety of forms. He produced sudden noises, such as screaming or dropping a plank of wood on the floor. He pinched the subjects on the arm and poked them with pins. He dropped pieces of ice down their back. And he also applied sudden pressure to their testicles.

Carmichael conducted his tests on two groups of subjects — a control group consisting of post-graduate students who had volunteered to participate in the study, as well as an experimental group, consisting of patients from London's National Hospital suffering from various forms of brain damage, specifically damage that had resulted in hemiplegia (paralysis of one side of their body).

Carmichael found that the shocks reliably caused the finger volume of the post-graduate students to shrink. The shrinkage typically began two or three seconds after the shock, reaching a state of maximum shrinkage six to twelve seconds later.

The brain-damaged patients displayed a similar response — except for those whose brain injuries included damage to the sympathetic nervous system. They didn't display the response, leading Carmichael to conclude that, "diminution in digital volume was dependent upon the integrity of the post-ganglionic sympathetic nerve-fibres."

Chart showing the response of a patient with damage to his cauda equina to sudden compression of one of his testicles

Carmichael found that other forms of stimuli could also cause fingers to shrink. For instance, threatening to punch the subjects in the face produced the response, as did having the subjects perform deep-breathing exercises or asking them to solve math problems.

This was not the first time Carmichael employed the technique of testicular compression during an experiment. In 1933, he had participated in a study that involved stacking weights on testicles (perhaps his own), in order to investigate the physiology of testicular pain.
  • Stürup, G., B. Bolton, D.J. Williams, & E. A. Carmichael. (1935). "Vasomotor responses in hemiplegic patients." Brain. 58: 456-469.
Posted By: alex | Date: Tue Aug 09, 2011
Category: Human Subjects, Physiology, Brain, 1900-1949, United Kingdom, Pain,
Some other topics you might find interesting:
Could it be that the guy was nuts???

Hi Alex,

Just avisitin' from WU. So far the site looks good.
Posted by Expat47 in Athens, Greece on 08/09 at 07:32 PM
I would have thought that with all the different methods for reaching the same results, compressing the testicles was unnecesary! ....Ouch doc! pour some ice down my back, will you?
Posted by mario in new jersey on 08/10 at 02:35 AM
One wonders if 'testicular compression' was listed on the release forms the volunteers signed!
Posted by David W. in 59101 on 08/12 at 06:44 PM
Interested that "testicular compression" was expected to induce a "fight or flight" response in males.
Whenever I apply testicular compression to my boyfriend, all he wants to do is curl up into a ball for 15 minutes and emit a high-pitched whimpering noise LOL!
Posted by uk girl in london on 09/14 at 05:15 PM
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