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SENSATION

How Lie Detectors Work

Perhaps you've seen them in movies and thought, "I could fool that lie detector machine." But could you really? Polygraphs, commonly called "lie detectors," are instruments that monitor a person's physiological reactions. But, despite their nickname, they don't "detect" lies. They can only detect whether deceptive behavior is being displayed. This is done in three key ways:

• By measuring respiratory rate: Two pneumographs, rubber tubes filled with air, are placed around the test subject's chest and abdomen. When the chest or abdominal muscles expand, the air inside the tubes is displaced. In an analog polygraph, the displaced air acts on a bellows, an accordion-like device that contracts when the tubes expand. This bellows is attached to a mechanical arm, which is connected to an ink-filled pen that makes marks on the scrolling paper when the subject takes a breath. A digital polygraph also uses the pneumographs but employs transducers to convert the energy of the displaced air into electronic signals.
• By measuring blood pressure/heart rate: A blood-pressure cuff is placed around the subject's upper arm. Tubing runs from the cuff to the polygraph. As blood pumps through the arm, it makes sound; the changes in pressure caused by the sound displace the air in the tubes, which are connected to a bellows, which moves the pen. Again, in digital polygraphs, these signals are converted into electrical signals by transducers.
• Via galvanic skin resistance (GSR): This is also called electro-dermal activity and is basically a measure of the sweat on your fingertips. Fingerplates, called galvanometers, are attached to two of the subject's fingers. These plates measure the skin's ability to conduct electricity. When the skin is hydrated (as with sweat), it conducts electricity much more easily than when it is dry.

Now that you know the basics, let's peek into the lives of polygraph examiners, look at some high-profile cases in which lie detectors were integral, and explore the countermeasures and legalities around polygraph testing. Read More at HowStuffWorks...

How BrainPort Works

A blind woman sits in a chair holding a video camera focused on a scientist sitting in front of her. She has a device in her mouth, touching her tongue, and there are wires running from that device to the video camera. The woman has been blind since birth and doesn't really know what a rubber ball looks like, but when the scientist rolls it in her direction, she puts out a hand to stop it.

The blind woman saw the ball. Through her tongue.

Well, not exactly through her tongue, but the device in her mouth sent visual input through her tongue in much the same way that seeing individuals receive visual input through the eyes. In both cases, the initial sensory input mechanism -- the tongue or the eyes -- sends the visual data to the brain, where that data is processed and interpreted to form images. It’s called electrotactile stimulation for sensory augmentation or substitution, an area of study that involves using encoded electric current to represent sensory information -- information that a person cannot receive through the traditional channel -- and applying that current to the skin, which sends the information to the brain. Read More at HowStuffWorks...

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