Most people arrive with an idea of a polygraph built entirely out of television: a bare room, a
hostile examiner, a needle jumping across a chart. The real thing is much quieter and much more
procedural, and almost everyone says afterwards that it was less dramatic than they expected.
Before you arrive
We talk to you first — usually on the phone — about what you want the examination to establish.
This matters more than anything that happens on the day. A polygraph can only answer narrow,
specific, factual questions. “Has he been unfaithful?” is not a testable question; “Did you have
physical contact with [name] between [dates]?” is.
The pre-test interview
This is the longest part of the appointment and it is the part people do not expect. We explain
how the instrument works, go through the consent paperwork, and then write the questions together.
You will see and approve every single question before anything is recorded. Nothing is hidden and
nothing is sprung on you.
There is a practical reason for this beyond fairness: a question you have not seen produces a
reaction to the surprise rather than to the subject. Reviewed questions give a cleaner result.
The recorded examination
Sensors are attached — typically two bands around the chest and abdomen, a blood pressure cuff on
the arm, and small sensors on the fingers. They record breathing, cardiovascular activity and
sweat-gland activity. Nothing is invasive and nothing hurts.
The question sequence is then read to you several times, in a fixed order, with pauses between
questions. Each pass takes only a few minutes. You answer yes or no — this is not the moment for
explanation, which is what the pre-test interview was for.
Afterwards
The examiner analyses the charts and discusses the outcome with you before you leave, and a
written report follows. If the result is inconclusive, we will say so plainly. That is a real
outcome, not a polite way of saying someone failed.
What a polygraph cannot do
It does not detect lies directly. It records physiological responses and an examiner interprets
the pattern of those responses across carefully constructed questions. It is not infallible, it is
not accepted as evidence in UK courts, and any examiner who tells you otherwise is overselling.
[OWNER TO REVIEW: confirm the sensor description matches your own instrument and procedure
before publishing.]