THE LIE-DETECTOR
By E. ASHWORTH UNDERWOOD URELY the chapel of Wycombe Abbey must have seen one of the strangest events in its history a few days ago, when an American corporal was tried for murder by an American court- martial which was held in it. During the proceedings an American army psychiatrist gave evidence that the accused had been subjected to the effects of a drug named pentothal, and that under its influence he had admitted that he had performed the act with which he was charged. This report is of much interest since lie-detectors and drugs employed to elicit statements which are stored in a person's subconscious mind have not been much used for legal purposes in this country. It has been estimated that every person charged with a criminal offence in Great Britain costs the community an average sum of £42, and of this about £37 represents the cost of detection. Much time and money have to be expended because of unreliable witnesses, and any legitimate aid which would reduce these costs should merit careful consideration.
Pentothal belongs to the group of hypnotics known as the bar- biturates. The chemical basis of these bodies is urea—said to be the first organic substance to be synthesised in the- laboratory (11328) —and it is combined with malonic acid and other substances. Barbi- tone—or veronal—is one of the parent members of the group, and other well-known examples are medinal, amytal, nembutal, evipan and luminal. The general effect of all these drugs is to hasten sleep, and if the concentration of the drug in the blood is increased by injecting it directly into the blood stream, some of them produce a degree of anaesthesia which is sufficient for certain surgical opera- tions. Pentothal itself, for example, is frequently used for operations on the bones. The patient loses consciousness rapidly after the injection is commenced, and on completion of the operation he sleeps quietly for an hour or so. If taken repeatedly all of these drugs tend to accumulate in the body, and this may be followed by broncho- pneumonia or by a coma which may be fatal.
The use of drugs such as amytal and pentothal in legal cases is based on the results obtained with them in psychiatric work. Dr. Broome, of Oldham, did some early preliminary work, but Black- wean in the United States in 5930, and Horsley in this country in 1936, appear to have been among the first to make systematic use 9f the narcosis produced by such injections in inducing the patient to reply to questions, without the controlling and inhibiting influence of the higher centres of the brain. The patient is unable to survey critically his own replies, though he is quite aware of his environ- ment and of the nature of the questions. During the Tunisian cam- paign of 1943 Grinker and Spiegel, to mention only two United States Army psychiatrists, had very successful results with patients who were suffering from the neuroses of war. This procedure— called by them " narcosynthesis "—was practised by the Americans in the forward battle areas, and as a result patients were able to relieve themselves at the earliest possible moment of the intense pent-up emotions which are inseparable from modem battle. Wilde and Sargent in this country have done similar work.
The next obvious step was the attempt to use a drug such as pentothal or amytal to enable replies to be obtained to certain questions of a compromising nature. In other words, these drugs were employed as so-called "truth sera," though the term " serum " is a misnomer. Lorenz of Wisconsin seems to have been one of the first to make use of this method, and he quoted three examples of its actual use in the case of persons charged with murder. Horsley in this country, as a result of his work in psychiatry, stated that the ease with which confessions had been elicited in more or less normal persons suggested that the method was a valuable approach to the problem of criminal investigation. In vino veritas might be a more appropriate description of the method than any tag embody- ing the phrase "truth serum."
The use of pentothal in criminal cases recalls the attempts which have been made during many years to evolve a scientific instrument which would detect lies. Except in the case of hardened criminals —convicted or unconvicted—lying is of course associated with certain physiological reactions, such as dryness of the mouth, swallowing or flushing, which may be so slight in degree as to be imperceptible to an observer. From the earliest times use has been made of these reactions, in much the same way that ordeal by battle was used to decide the just cause. In China it was once the practice to compel a subject to chew rice while he was being cross-examined, and then to produce the rice for inspection. Since lying inhibits the secretion of the salivary juices, if the rice was produced in the dry state, the guilt of the suspect was accepted as proved. There are other physiological reactions, however, which are caused by lying, and which are by their nature not susceptible to casual obser- vation; Among these are the pulse-rate, the rate and type of breath- ing, and changes in the blood pressure. As long ago as 1914 Benussi used as a lie-detector variations in the ratio of the inspiratory period to the expiratory period in one complete respiration, and three years later Marston introduced a blood-pressure test. More recently (1926) Keeler in America devised a modification of the "polygraph," an instrument invented by our own Sir James Mackenzie in his studies on the heart and circulation. Keekr's polygraph records simul- taneously on a moving sheet of paper records of the blood-pressure and of the respirations. This instrument has been much used by the police in America, and the Michigan police have now had ten years of experience of the method. A case in which a lie-detector, of a type not specified, was employed in Michigan has been reported within the last few days.
It may be interesting to glance for a moment inside a room at police headquarters in some American city when, a polygraph examination is being carried out. The room is quietly and tastefully furnished in office style, and the operator of the polygraph is dressed in mufti. The subject is seated in a comfortable chair with his back towards the instrument, and the variations in his pulse and respirations are
• transmitted from soft pneumatic tubes atOUDfi his arm and his chest to the writing pens on the instrument. After a-preliminary trial run the operator proceeds to ask the subject about ten questions, two or three of which will be of a compromising nature, while the others are perfectly innocent and straightforward. The answer given to each must be " Yes " or "No." Experience shows that a lie declares itself on tht tracing as an abnormal movement of the pens. The Michigan State Police have found that the greatest value of the polygraph is in clearing innocent persons. It has been estimated by competent authorities that the Keeler polygraph is only 75 per cent. accurate. On the other hand, the Summers pathometer, which it is claimed demonstrates a lie by means of a variation in the electrical resistance of the skin to an electric current, is supposed to detect 98 per cent. of guilty persons and too per cent, of the innocent.
There are obviously certain dangers associated with such methods. and all authorities are agreed that certain safeguards must be practised in their use. Such tests have been systematically observed in the United States for twenty-six years. As long ago as 5932 Lorenz of -the University -of Wisconsin laid it down that the rimmination
with such drugs as pentothal should preferably be carried out in the presence of representatives of both sides. The doctor's function is simply to administer the drug, and then to start the subject talking. The person to be examined should be informed of the nature of the test, and he should voluntarily give his consent. If a suspect is convinced that he is innocent, and during the examination he happens to confess to any other minor crimes, he should not be called upon to defend himself against such charges. These main principles still apply. Although the United States police use polygraph evidence to a considerable extent, only a few attempts have ever been made to introduce it in court. There are no set standards for apparatus or operators. In 1933 the Wisconsin court held that "the admission of the lie-detector may easily result in the trial of the lie-detector rather than the issue of the case." In 1938 a New York court ac- cepted pathometer evidence, but in a murder trial which was held rather later the court refused to admit such evidence. In 1942 the Supreme Court of Michigan ruled that the admission of such evidence would be an error until it was established that reasonable certainty could be deduced thereby. The British courts do not appear ever to have admitted evidence of this nature.
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