The PSE grew from an effort to improve a polygraph. Standard polygraphs measure four variables: pulse, blood pressure, respiration and perspiration. Some to measure additional physiological variables. The more variables measured, the more reliable the polygraph.
Bell and McQuiston discovered that the frequencies composing the human voice are not fixed; they shift very slightly from right to fourteen times every second. But when the speaker is under stress, this normal frequency modulation disappears. What remains are the pure component frequencies of the voice. And a strong indication that the speaker is lying.
The two men developed a device to test this phenomenon and planned to use it as an additional “channel” on the polygraph. They discovered that the new variable was so reliable and accurate a measure of psychological stress there was really no need to measure the other polygraph variables.
Freed from the necessity of strapping the subject into a chair, stretching a pneumographic tube across his chest, gluing electrodes to his palms and clamping his arm in a blood-pressure cuff, the PSE proved to be much more versatile than the polygraph. Because it can work from a telephone or tape recorder, the PSE can be used without the knowledge or even the physical presence of the subject.
I asked Colonel Bell to tell me about some of the things the PSE was being used for, especially cases in which a conventional polygraph couldn’t be used. He mentioned that the police in Howard County, Maryland, have been using the PSE for two years; they’ve had great success in establishing the innocence of suspects who were afraid to submit to a polygraph examination because that machine’s forbidding aspect.
Bell went on to describe some of his invention’s other uses, actual or potential. Doktor and the Federal government are exploring its use as a defense against skyjackings and telephoned bomb threats, and as a means of speeding up customs inspections. Some doctors and psychiatrists are using PSEs to study patients’ physical and mental stress. The National Committee to Investigate Aerial Phenomena, a private group that investigates UFO reports, is now using the PSE to interview witnesses of UFO sightings.
I asked Bell if he would lend me a PSE experiment with, in order to write a piece about the device. He agreed, with two conditions. First, I must take Doktor’s three-day course in operating the instrument; second, after using the PSE, I must review my interpretation of its output with his staff, in the interest of accuracy. This seemed reasonable, so I agreed.
The course was held in the meeting room of a Holiday Inn in Falls Church, Virginia. Eight other students were employees or customers who had purchased the device. These included a private detective now in Pennsylvania, a New York chain store, and the security service of an East African country. The instructor was Mike Kradz, a criminologist and retired police officer. Kradz projects the tough-cop image, but he is a living rebuttal to the Police joke. There is nothing about forensic science, from fingerprints to polygraphy, on which the man is not an expert.
The first morning of the course was devoted to the physical operation of the PSE. The device is used in conjunction with a Uher tape recorder, which has four speeds and can be manually wound back to locate a particular point on the tape. The testimony to be evaluated is recorded at a tape speed of 7½ inches per second, then played back and stopped at the beginning of the utterance in question. The recorder is slowed to 15.16 inches per second and played. The sound, no longer recognizable as a human voice, is a long, low rumble.
The PSE itself is built into an attaché case. The case opens to reveal a chart drive, similar to an electrocardiograph, and a number of buttons and knobs. A single cable connects the PSE to the tape recorder.
As the tape recorder reels slowly turn, and a rumble issues from its speaker, the PSE stylus dances back and forth across the moving chart paper, leaving behind a ragged trail. Then the recorder is stopped, the chart paper is stopped, and that’s all there is to it. The result is a strip of paper with a squiggly line. The rest is up to the human eye and brain.
On the afternoon of the first day, Kradz showed us what to look for. The unstressed voice looks like an untrimmed hedge, with stalks of different heights sticking up (and down) at irregular intervals. But add some stress, and that hedge begins to look trimmed. The greater the stress, the smoother the shape. If the subject was experiencing the hard stress which accompanies deception, the over-all outline of the figure tends to take on a rectangular shape, a concertina as seen by the player. Kradz showed slide after slide of charts made during actual police interrogations. He told us the background of each case and pointed out the tell-tale signs of deception, whenever they were present.
That night each student took a PSE back to his room to practice operating it. Some coordination must be learned to become facile in handling the recorder and the PSE, but clearly the difficult part of the course would be learning how to read and interpret the charts.
The next day we learned the theory of polygraph interrogation, which applies to the PSE. There is, first of all, the matter of the “outside issue.”
Most people, Kradz pointed out, have some sort of deep secret they don’t want known. When faced with a polygraph examination, a person may be more concerned that this outside issue may come to light than he is about the actual substance of the interrogation. This can produce irrelevant stress in some of his answers, and mislead the examiner. Therefore it is necessary for the examiner to interview the subject before the examination, go over all of the questions he intends to ask, and assure the subject he will ask only these questions.
I had reason to remember this later, when I ran my first real interrogation tape.
The interrogation always includes the question, “Are you afraid that I will ask you about something we have not discussed?” A negative answer with no sign of stress eliminates the outside-issue problem. Also, the examiner always asks some innocuous questions, such as, “Do you like the color blue?” in order to observe the subject’s general state of tension. And there is always one “red-herring” question.
The red herring is used to identify the “guilt complex responder.” Such a person shows stress when he responds to any accusatory question. The examiner may ask, “Did you steal the watch?” when it is money, not a watch, that is missing. A stressed denial will alert the examiner, who carefully compares this response to the stress produced by questions about the missing money.
That night the class was given tapes of real police interrogations. In most cases, Kradz was the examiner; and in every case, he knew the background and resolution of the matter. One case I was assigned concerned a young man accused of stealing money from his father’s store. Kradz started by asking the “outside-issue” question. No, the young man replied, he was not afraid. Kradz would ask him a question they hadn’t discussed. Then the following exchange took place:
> “Do you live in Howard County?”
> “Yes.”
> “Do you suspect someone of having taken the money?”
> “No.”
> “Are you wearing a white shirt?”
> “Yes.”
> “Do you know who took the money?”
> “No.”
> “Are you wearing a ring?”
> “Yes.”
> “Did you take the money?”
> “No.”
There were a few red-herring questions to check for the guilt complex response. The questions about wearing a white shirt and a ring and living in Howard County had been included to measure the background stress elicited by irrelevant issues.
I ran the tape and charted it on the PSE. All but two of his responses were unstressed. The question about suspicion
---
6
The more I read,
the more I doubted
the official account of
what happened
that day in Dallas
9