If Machines Can't Dectect Feelings, How Do Lie Detectors Work?

Question

They can't sense dishonesty, so how can the know anything but something different has happened in someones brain?

Answer 1

it's magic

Answer 2

The lie detectors do nothing, but measure the heart rate, perspiration, and voice stress of the person who's answering the questions.

When taking a lie detector test, the machine does nothing but record these three things on a rolling sheet of paper. The operator marks on the paper right after they've asked a question. The whole time, the lie detector marks heart rate, perspiration, and voice stress / inflection with needles on the paper.

So the operator is only marking on the paper when they asked a question, as these three things are continually recording all of these body measurements.

Afterwards, the operator of the lie detector rips all the paper from the machine, takes it into a back room, and observes it to see if there were rapid heart beats, lots of sweating, or voice changes, after they asked a question.

So again the lie detector does nothing except record these 'feelings', and it is always up to the doctor to interpret it.

ALSO: They may decide to take blood pressure tests but I believe the heart rate is a better indicator of whether you're afraid that you're lying.

Answer 3

Lie detectors detect changes in bodily functions like heartbeat, breathing, perspiration which, evidently, are clues as to whether someone is lying or not.
It IS possible to beat a lie detector test (sociopaths are very adept at that). And, as far as I know, the results of lie detector tests are still inadmissible in court.

Answer 4

Who told you that machines cannot detect feelings? Sure they can.

Computers can use complex algorithms to analyze such diverse things at tone of voice, facial expression, temperature, perspiration levels, even brain scans -- combining all this data computer can make very good predictions about feeling of a human.

Also, as our technology improves commuters are getting better and better at tasks like this.

Answer 5

A lie detector works by measuring a persons blood pressure and heart rate. Usually if a person is lying their blood pressure and heart rate will increase.

Answer 6

Usually when people lie, they worry ever so slightly about being found out, even if they don't recognize it. Thus, stress levels go up, and the machine can detect these.

Needless to say, these aren't foolproof.

Answer 7

They don't sense "feelings". They sense biological changes such as pulse rate and breathing changes, and using known combinations of changes in those responses, determine that there is a likelihood that the person is lying.

Answer 8

lie detectors work off our your heart rate and variations in your voice. that is why a strap is secured around your chest and they put things on your fingers to feel your pulse.

Answer 9

it is not detecting feelings per say, it is monitering the difference between your breathing patterns and your blood pressure, which can indicate that you are nervous if lying, or if everything is normal, that you are telling the truth. it's all about body changes rather than actual feelings.

Answer 10

they detect physical changes in your body,,,, heart racing, blood pressure going up,,,,,, most people ,when they lie , have these changes happen,,,,,,,,, that is why lie detectors are not reliable,,,,,,, some people also know how to control their bodies

Answer 11

When you lie, certain physiologic changes occur.

This is what the lie detector picks up.

It's not very reliable, however. It can be tricked.