Penile plethysmograph Guide, Meaning , Facts, Information and Description
The penile plethysmograph (PPG) is a controversial device that measures changes in blood flow in the penis in response to audio and/or visual stimuli. It is typically used to determine the (supposed) level of sexual arousal as the subject is exposed to sexually suggestive or explicit content, such as pornographic photos, movies or audio.The plethymograph has value in screening organic versus psychogenic impotence. Lack of sexual response during REM sleep indicates further evaluation by a urologist.
There are two types of penile plethysmographs:
- Volumetric air chamber: When this is placed over the subject's penis, as tumescence increases, the air displaced is measured.
- Circumferential transducer: This uses a mercury-in-rubber or indium/gallium-in-rubber ring strain gauge and is placed around the shaft of the subject's penis to measure changes in circumference.
The device has also been used in law enforcement and in psychological experiments. One study demonstrated that experimental subjects could be conditioned to show sexual arousal (as indicated by the device) in response to images of shoes, by initially preceding the shoe images with pictures of nude women. The experimenters inferred that the behaviourist concept of conditioning was likely to be an important influence in sexual fetishes.
Significant suppliers of PPG machines include Farrall Instruments Inc., Medical Monitoring Systems and Behavioral Technology Inc. The device is known to be used in Brazil, Britain, Canada, China, Czechoslovakia, Hong Kong, Norway, Spain, and the United States.
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In the United States, a scientific technique can't be used as evidence in court unless the technique is "generally accepted" as reliable in the relevant scientific community. This was decided by the Supreme Court in 1993 and is called the Daubert Standard.
Plethysmography cannot meet most legal thresholds as a valid or relevant diagnostic tool for the following reasons:
The device has also been used in many states when evaluating convicted sex offenders. The sexual assault trial of basketball player Kobe Bryant in Colorado brought this device and its use to public attention before the case was dropped in 2004, because Colorado law would have required evaluation with this device following conviction.
After developing the device in Czechoslovakia, developer Kurt Freund fled to Canada in the wake of the Prague Spring. Freund then began using the device at the Clarke Institute in Toronto, where much of the research and published data using the device originated.
Use of PPG followed in the wake of the "fruit machine," a slang term for another device developed in Canada in the 1950s and 1960s as part of a Royal Canadian Mounted Police campaign involving the identification and dismissal of every gay person in the employ of the public service.
A roughly equivalent procedure for women, vaginal photoplethysmography, measures blood through the walls of the vagina, which researchers claim increases during sexual arousal.
This is an Article on Penile plethysmograph. Page Contains Information, Facts Details or Explanation Guide About Penile plethysmograph United States
In State of North Carolina v. Spencer, the court reviewed the literature and case law and concluded that penile plethysmography was scientifically unreliable: "Despite the sophistication of the current equipment technology, a question remains whether the information emitted is a valid and reliable means of assessing sexual preference."Canada
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