Lie detector tests: in search of the truth


One machine has made it easy to get caught in a lie. By tracking the heart beat, blood pressure and sweat glands, a lie detector test can untangle any web. One company in St. Albert administers the tests to get to the truth.

“We want to do the right thing for everybody. I want to give the person who didn’t do it a chance to clear their name,” said Ken Donaldson, owner of ITR Polygraph.

Since the Middle Ages people have attempted to find ways of telling when someone is lying or telling the truth.

In 1730, an English writer, journalist and spy wrote an essay suggesting that checking the pulse is a practical way to catch a criminal. Daniel Dafoe wrote that the pulse quickens when someone is caught in a crime.

“It is true some are so harden’d in crime that they will boldly hold their faces to it … but take hold of his wrist and feel his pulse, there you shall find his guilt,” Dafoe wrote in An Effectual Scheme for the Immediate Preventing of Street Robberies and Suppressing all Other Disorders of the Night.

The polygraph test was invented in Berkeley, California in 1921. According to Forensic Psychophysiology Using the Polygraph, a young psychologist named John Larson – who was employed by the Berkeley California Police Department – took a keen interest in connecting the body’s physiological response when telling a lie.

He developed an instrument that measured respiration and cardiovascular changes on a polygraph.

Today there are various models of lie detector tests, and ITR Polygraph uses an Lafayette LX4000, which Donaldson said was used previously by the RCMP and the Edmonton Police Service.

“That’s one of the reasons that I got it, plus their software is so much easier than the other ones.”

How it works

The machine comes with two respiration input channels, which are two cords that stretch across the chest and torso. It also comes with a blood pressure cuff and two pieces of fabric for the fingertips to measure galvanic skin response (the activity of sweat glands in the fingertips).

While the machine would accurately tell changes in the body, the test needed a way to differentiate when an individual was lying or telling the truth. In the early 1900s the relevant/irrelevant test was created, a tactic still used today.

During the test the subject will be asked questions relevant to the issue at hand, as well as questions not relevant to the issue. Based on the body’s response to the different questions, the examiner gets a reading on when the subject is being truthful or deceptive.

Another tool used is called the numbers test, a common tool used by ITR Polygraph. The test is administered before the actual exam takes place, allowing the examiner to get a reading on when the subject is being honest or not.

The subject is given a slip of paper and is told to write down a number between one and 10. Once the number is etched into the surface of the small square, it’s tucked underneath the subject’s leg, out of sight.

The examiner will ask: “Did you write the number one?” to which the subject will reply: “no”.

The examiner will ask the same question all the way up to the number 10, and the subject is directed to answer “no” each time.

At the end, the results will show when the examiner asked about the correct number, the body’s blood pressure, heart rate and galvanic skin response spiked.

“The number test gives us a reading on when person is telling the truth,” he said.

Today the lie detector test is used for a variety of reasons. Policing divisions use the test while interrogating suspects, employers use the test if an employee has been suspected of a work-related crime and spouses use the test to investigate infidelity.

“Every day we have people coming in here to test on sexual infidelity,” he said. “It’s one of the most common reasons people come in here.”

Interestingly, some companies require a lie detector test prior to hiring an employee. The RCMP, for example, administers a pre-employment polygraph to verify an applicant has been truthful in the information they’ve submitted.

Reasons why people get the test

At ITR Polygraph, Donaldson is often sought out to test for infidelity in relationships or by lawyers looking for an independent business to administer the test. Co-owner and wife, Lesley Donaldson, said the police can be biased in the questions they ask, often leading to false confessions from suspects.

“They believe you did the crime, so there will be no nice interview. There’s no creating the questions to suit you, they will make the questions to suit their topic,” Lesley said. “If you are charged with a crime and you have a lawyer, we work with most criminal defence attorneys in Edmonton, Vancouver, Calgary and Toronto.”

Before the lie detector test is administered Ken and Lesley will sit with the clients and decide what questions will be asked. The session takes about two hours, giving the tester and the subject enough time to get comfortable with each other.

Once the questions are determined, the subject is lead to a small room where the equipment is set up. The walls are beige and bare with a small camera being the only object in front of them.

Pictures and paintings are absent from the naked neutral walls, preventing the subject from getting distracted in the middle of the test. Ken said any stimulus could throw off the readings, so the subject needs to have as little around them as possible.

The test is administered three times, with the last time being the one that counts. That helps the subject get over any jitters they may have during the test.

“Everyone is nervous, so I’m going to get you used to sitting there having the apparatus, the timing, the pace of the questions,” he said. “The relevant test, I’m going to run through that three separate times so even if you’re nervous, you know exactly what question I’m going to ask in exactly what order.”

The test: is it reliable?

Since the lie detector test started being used as a tool to uncover the truth, counter measures have cropped up with promises to beat it. They range from putting pins in the bottom of shoes to practising meditation in order to control the breath.

Ken said, however, no measure will match the test. A pin in the foot will cause a pain reading instead of a fear reading, telling the tester that the subject is in pain rather than telling the truth.

Controlling the breath also doesn’t work. He said the tester will often speed up or slow down the breath in an attempt to throw off true and false readings. If he notices the breathing is being controlled, he’ll tell the subject they need to stop or they’ll fail the test.

Donaldson said there are other ways people try to throw off the test, but nothing gets past him.

“I love counter measures because they’re so obvious,” Ken said. “It’s ridiculous. I’ll get a reading that’s so huge and ridiculous, I’ll just tell them to stop it … If they continue, I’ll tell them I’ve got to re-ask you that question, sit still. After about three more times, I’m going to take the equipment off of them and tell them to get out of my office and stop wasting my time.”

In the end, any counter-measure used will result in a failure of the test. Ken said if someone is truthful, they wouldn’t need to use a counter-measure to begin with.

In the case of infidelity, often Lesley will sit with the couple afterwards to talk through the next steps.

“I don’t have education in counselling, but I’ve been married for 25 years,” she said. “So I’ll sit with the couple and we’ll talk through the results together. Some of the situations that they’re going through I can speak to based on my own personal experiences being married.”

ITR Polygraph operates in the NABI office in Campbell Park. For more information or to book a session go to:


About Author

Dayla Lahring

Dayla Lahring joined the St. Albert Gazette in 2017. She writes about business, health, general news and features. She also contributes photographs.