The vintage era of polygraph instruments is marked by significant contributions from several key manufacturers, each of whom developed unique models that have become iconic in the field of lie detection. This article provides a detailed exploration of some of the most notable manufacturers and their vintage analog polygraph models, highlighting their technical specifications, features, and historical significance.
1. Stoelting Co.
Manufacturer: Stoelting Co.
Notable Model: Stoelting Deceptograph (circa 1940s-1960s)
Stoelting Co. is one of the oldest and most respected names in the polygraph industry, with a history dating back to the early 20th century. The Stoelting Deceptograph was one of their flagship analog polygraph models and was widely used by law enforcement agencies across the United States.
- Features:
- Channels: The Deceptograph typically included four channels for recording cardiograph (heart rate), pneumograph (respiration), galvanic skin response (GSR), and a movement sensor.
- Kymograph: Utilized a motor-driven kymograph to record physiological data on a rotating drum with paper.
- Construction: The Deceptograph was housed in a robust metal case with a lacquered wooden panel, giving it a distinctive, professional appearance.
- Calibration and Accuracy: The Deceptograph featured manual calibration dials for each channel, allowing examiners to adjust sensitivity based on the subject’s baseline readings.
Historical Significance: The Stoelting Deceptograph was a workhorse in the field of polygraphy during the mid-20th century, known for its reliability and accuracy. It set the standard for polygraph instruments during this period.
2. Lafayette Instrument Company
Manufacturer: Lafayette Instrument Company
Notable Model: Lafayette Model 76056 Polygraph (circa 1950s-1970s)
Lafayette Instrument Company is another key player in the history of polygraph instruments. The Model 76056 is one of their classic analog polygraph devices, renowned for its precision and durability.
- Features:
- Channels: The Model 76056 included multiple channels for cardiograph, pneumograph, and galvanic skin response (GSR).
- Kymograph: This model used a high-quality, synchronous motor-driven kymograph, which provided consistent and reliable recording speeds.
- Sensitivity Controls: It offered finely tuned sensitivity controls for each channel, which were essential for detecting subtle physiological changes.
- Design: The instrument was encased in a sleek metal box with a fold-out panel for easy access to the controls and paper feed. The build quality was superior, reflecting Lafayette’s commitment to precision engineering.
Historical Significance: The Lafayette Model 76056 was widely adopted by federal agencies and private examiners alike, earning a reputation for its ruggedness and consistent performance in various testing environments.
3. Associated Research, Inc.
Manufacturer: Associated Research, Inc.
Notable Model: AR Polygraph (circa 1960s)
Associated Research, Inc., known for its broad range of scientific instruments, also made significant contributions to the field of polygraphy with their AR Polygraph model.
- Features:
- Channels: The AR Polygraph featured up to four channels, typically including cardiograph, pneumograph, GSR, and a finger plethysmograph.
- Recording Mechanism: The instrument used a dual-pen kymograph system that allowed simultaneous recording of two physiological responses on the same strip of paper.
- Control Panel: The AR Polygraph’s control panel was laid out for easy access, with large, clearly marked dials and switches. It included both manual and automatic calibration options.
- Portability: Although robust, the AR Polygraph was designed to be relatively portable, with a sturdy handle and compact dimensions compared to earlier models.
Historical Significance: The AR Polygraph was a favorite among private examiners due to its portability and reliability. It was also one of the earlier models to integrate advanced calibration features, improving the accuracy of the tests.
4. Heathkit
Manufacturer: Heathkit
Notable Model: Heathkit Model GD-1217 Polygraph (circa 1960s-1970s)
Heathkit, a well-known name in the DIY electronics community, offered a unique polygraph kit that allowed users to build their own polygraph instrument. The Model GD-1217 was particularly popular among hobbyists and small-scale operators.
- Features:
- Channels: The GD-1217 included three basic channels: pneumograph, galvanic skin response, and cardiograph.
- Kymograph: Unlike more professional models, the GD-1217 used a simple mechanical drum that could be manually adjusted for speed.
- DIY Assembly: The kit came with all the necessary components, including detailed instructions, making it accessible to hobbyists who wanted to learn about polygraphy.
- Construction: While not as durable as commercial models, the GD-1217 was a testament to Heathkit’s philosophy of making advanced technology accessible to the masses.
Historical Significance: The Heathkit Model GD-1217 is notable not only for its functionality but also for its role in democratizing access to polygraph technology. It remains a collectible item today, cherished by vintage electronics enthusiasts.
Conclusion: The Legacy of Vintage Analog Polygraph Instruments
Vintage analog polygraph instruments, produced by manufacturers like Stoelting Co., Lafayette Instrument Company, Associated Research, Inc., and Heathkit, played a pivotal role in the development of modern lie detection. These devices, with their intricate mechanical designs and manual calibration features, required a deep understanding of both technology and human physiology.
While these instruments have largely been replaced by modern digital polygraphs, their legacy endures. Collectors and historians continue to value these vintage models not only for their historical significance but also for the craftsmanship and innovation they represent.
For those interested in the history of forensic science or vintage technology, these analog polygraphs offer a fascinating glimpse into the early days of lie detection, when mechanical precision and human expertise worked hand-in-hand to uncover the truth.