Cesare Lombroso, a famed criminologist, described a primitive lie detector calle

Question

Cesare Lombroso, a famed criminologist, described a primitive lie detector called a volumetric glove in his 1876 book Criminal Man: "The glove is filled with air, and the greater or smaller the pressure exercised on the air by the pulsation of the blood in the veins of the hand acts on an aerial column. . . . [T]his chamber supports a lever carrying an indicator which rises and falls with the greater or slighter flow of blood in the hand." Explain the science (gas laws) of how the volumetric gloves function as a lie detector.

Explanation / Answer

This is called as Plethysmograph. In this gas law applied is Boyles law. Plethysmography is used to measure changes in volume in different parts of the body. It measures these changes with blood pressure cuffs or other sensors. These are attached to a machine called a plethysmograph. Plethysmography is especially effective in detecting changes caused by blood flow. They’ll be most interested in checking your systolic blood pressure. That’s the pressure of blood in your arm and leg when your heart contracts. Using the data from the plethysmography requires use of Boyles Law PV = constant

When a person giving false statement (lie) then his heartbeat rate changes, consequently pumping blood into veins increases due to fear, anxiety, nervousness. This will lead to change in pressure/volume ratio.

If the blood volume (V) increases in the veins it creates additional pressure on gloves (squeezing a ballon) pushes the volume up in the meter reading. This is a sudden change can be detected.

This trick is used to identify whether a person is lying or not, but it is not a scientific standard. In earlier days good people are fear towards police and laws due to they do not want to lose their social status. Nowadays cheaters can cheat the polygraphy and makes the investigation more complexity

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.