You can fool a lie detector—if you're willing to try.

You've seen it in movies and TV shows, right?
You're made to sit in a chair,
sensors are wrapped around your fingers,
a belt is strapped around your chest,
and you're asked, "Are you lying?"—that device.

A polygraph.
Commonly known as a lie detector.

Have you ever been hooked up to one?

Probably not.
Usually, you wouldn't be.
But if it ever happened... you would definitely panic.

Your heart would start pounding, your palms would get damp, and your eyes would dart around.
Even if you tell yourself, "I have nothing to hide," your body confesses first.

But that machine isn't as infallible as you think.
Or rather, once you know how it's built... you can fool it.

Today, that's what we're talking about.

1 | What is it actually measuring?

First, let's flip the premise.
Polygraphs do not detect "lies".

What it's picking up are physiological reactions of the body.
Specifically,
electrodermal activity (sweat on the palms),
heart rate,
blood pressure,
and breathing rhythm.
It records the waveforms of these four channels in real time.

When humans lie, they experience stress regardless of whether they are aware of it.
The subtle tension of "I might get caught" stimulates the sympathetic nervous system,
causing sweat to bead on the palms,
the heart rate to jump slightly,
and breathing to become shallow.
The polygraph is merely visualizing that "fluctuation,"
the disturbance of the autonomic nervous system, as a graph.

None of these measure "lies" at all.
In other words.
What that machine is looking at is not the "presence of a lie," butthe "presence of tension.".

"The moment a human lies, their autonomic nervous system reacts automatically"—everything is built on that premise.

...And that premise is much more fragile than you think.

2 | The baseline of control questions

You need to know the flow of the examination.

In a polygraph test, they first ask"control questions."These are questions where the answer is already known.

"Is your name so-and-so?" "Is today Tuesday?"
...YES.
This is recorded as"the waveform when telling the truth."It's the baseline.

Next, the real questions are mixed in.
"Did you steal such-and-such?"

What the examiner is judging is the
differencebetween the waveform of the control questions and the waveform of the real questions.If the waveform is clearly more erratic during the real question,
it is judged as, "You are feeling stress from this question, so there is a high possibility you are lying."

Conversely, if there is no difference... it means nothing has happened.

Simple, right?
Too simple, right?

3 | Breaking the Baseline

Having read this far, you should see it by now.

The way to deceive is simple.
There is no need to "hide the lie."
You just need to corrupt the "truth" instead.

Once you break the baseline, the "criteria for judgment itself" goes haywire.

While answering control questions,
curl your big toe inside your shoe with all your might.
Lightly bite the edge of your tongue with your back teeth.
Or... press a thumbtack hidden in your hand into the pad of your finger.

Pain stimuli force the sympathetic nervous system to fire.
Regardless of the stress of lying,
your heart rate jumps,
you sweat,
and your breathing becomes irregular.

The exact same physiological response as when you lie
is recorded at the moment you are supposed to be "telling the truth."

As a result, the baseline becomes erratic.
Even if your waveform fluctuates when you lie during the critical question,
to the examiner's eyes, it just looks like "the same level of fluctuation as before."

The difference disappears.
There is no longer a place for the lie to stand out as a lie.

This is called acountermeasure.
A thumbtack is an extreme example, but in reality, even more subtle methods work.

Clenching your anal sphincter,
curling your toes,
doing mental arithmetic.

You just need to shake your sympathetic nervous system in a place invisible to the examiner.
When you are answering truthfully,
you just need to bring your body into a state of lying.

It's over.
With just that, the machine goes silent.

4 | People You Don't Even Need to Break

There is one more scenario where a polygraph goes silent.

People with high psychopathic tendencies.
...The type whose autonomic nervous system barely fluctuates even when they lie.

They aren't afraid when they lie.
They think it's fine if they get caught.
In the first place, their emotions are hard to shake.

In front of such people, a polygraph becomes a mere ornament.
Because there is no reaction, the machine judges them as "honest."

For those who watch anime like 'PSYCHO-PASS',
it should be easy to visualize.
It was depicted as the hue of a psychopath.

It's not about whether you're lying.
Whether you've become agitated is all that machine can see.

Now, consider the opposite.

You are an honest person.
You have nothing to hide.
But during the test, you suddenly think:
…'What if they think I'm lying because of this question?'

In that instant,
your heart rate spikes.
Your palms get damp.

That alone makes the needle move.
That alone makes you a 'liar'.

In other words, this machine
is designed to be more easily triggered by honest people than by liars.

Ironic, isn't it?

5 | The 'pros' know

Naturally, the people conducting the tests aren't stupid either.

At U.S. federal agencies,
they sometimes install pressure sensors under the seat of the subject's chair
to monitor the movement of the muscles in the buttocks and thighs.

If you move your toes, the pressure on the seat changes, and
if you tense your sphincter, it causes subtle shifts in body weight.

However, for 'hard-to-detect countermeasures' like biting your tongue or doing mental arithmetic,
current testing technology has almost no effective countermeasures.
It's a realm that relies solely on the examiner's experience and intuition.

In 2003, the National Academy of Sciences (NAS)
published a comprehensive review on polygraphs.
The conclusion was this:

'The accuracy of the polygraph is insufficient to be relied upon as scientific evidence.'
…In short, in the academic world,
the conclusion that 'that machine cannot be trusted' was reached long ago.

6 | Doubt your own judgment

Now then.

After reading this far, what has been born within you?

'Huh, so you can fool a polygraph.'
'A thumbtack might be impossible, but moving my toes seems doable.'
'I feel like I've gotten a little smarter.'

…If that's what you thought,
you should read this article again from the beginning.

What I explained in this article is that
a polygraph is not a machine that measures "lies," but simply one that measures "tension."
And that its baseline can be easily corrupted.

In other words...
The machine itself is a flawed tool for detecting lies from the very start.

The knowledge you think you've gained on "how to deceive"
is nothing more than a way to outsmart a flawed product.
What is the point of beating a flawed product?

The thing you should really be wary of is not the machine.
It is the person sitting in front of you.

A polygraph only looks at heart rate and perspiration.
If you break the baseline, it goes silent.
But the things a human leaks when they lie are much more subtle and much more numerous.
And human eyes... even without a baseline, they pick up on your lies.

The pitch of your voice.
The way you avert your gaze.
The frequency of your blinking.
The length of the pause before you answer.
The meaning behind the very act of repeating the question.
Crossing your arms, touching your nose, leaning back in your chair.

Your body is much more honest than you think.
It all happens subconsciously.
Therefore, you cannot stop any of it yourself.

I don't use polygraphs.
Because there is no need to rely on such a machine.

...I will talk about that in the next article.

▶ Your lies are already visible—Mind reading that doesn't require a machine

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