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Sci Tech
Held by the eye of the beheld
EVERY TIME you take an international flight, you go through the ritual. The airline staff asks you: "Did you pack the bags yourself? Has anyone given you anything? Do you know the contents of every bag you carry?" and so on. You keep mumbling "Yes" to each question and both of you think the security issue is taken care of. You know that you are not a security risk and she takes your answers at face value and lets you in. Any security risk person can lie through his teeth and get away with in. The hassled airline staff is also in no condition to look you in the eye and decide whether you are "safe" or a risk just by your answer. She has to handle over a hundred passengers within half an hour, and you rush her too by uttering your yeses. Some passengers are tired, nervous, timid or jumpy. Their gestures and tones may sound suspect but shifty eyes and nervous gestures are not reliable indicators of dishonesty. Surely there must be a better method than this to check whether the passenger is speaking the truth or not!
The police and investigative agencies use the lie detector or the polygraph to do this. The subject being questioned is made to sit on a chair and a whole set of detectors is stuck to his wrists, chest, head and so forth. These measure changes in pulse rate, breathing, sweating and other responses. The principle behind this method is that when telling a lie, the subject's response will necessarily be different from those when he answers truthfully. The polygraph method is clearly more humane than "third degree' methods. The latter can produce false confessions, since the subject may admit to anything just in order to escape to time. The lie detector measures the effects of the hormonal rush, which produces a set of involuntary give-away responses when the subject tells a lie. In the hands of experts, it offers a 80 per cent success rate.
Clearly the polygraph method is not suited for mass screening in an airport or other fast-traffic and high throughput situations. It needs skilled personnel, subjects have to be attached with sensors for several minutes, the data analysis takes time and the interpretation of data delayed. The need for an instant method of detecting deceit is obvious, given the current circumstances of the world. The method must be at least as reliable as the polygraph, should be as fast as the walk-through metal detectors, should be just as non- invasive, and preferably non-obtrusive and blend into the background.
Thermography
Such a method has been suggested by Dr. James Levine, an endocrinologist at the Mayo Clinic, along with Drs. Ioannis Pavlidis and Norman Eberhardt, two engineers working at the Honeywell Laboratories, all at Minnesota, USA. Writing in the 3 January issue of the journal Nature, the trio recommends the technology called high-definition thermal imaging of the face. As early as 1975, Drs.A. H. Barrett and P. C. Myers had explored the possibility of measuring thermal radiation, or heat waves, emitted from surfaces and using microwave receivers. Temperature differences of as little as 0.1° C and a resolution of 1-2 cm was obtained. More usefully, heat radiating from layers a few cm below the surface could also be detected. This methodology allowed them to detect temperature differences in human faces and tissues. The earliest application they put it to was to detect malignant tumour growth under the skin, such as in breast cancer. Detection here is possible because blood flow in a normal tissue region is higher than in a tumour lump. The latter is therefore seen as a lower temperature zone, and so detected. The method came to be known as microwave thermography. Twenty years later, Drs. B. M. Gratt and E. A. Sickles of the University of California at Los Angeles used this idea to detect and rapidly and quantitatively analyse blood flow differences between different regions of the human face.
Last year, Drs. Levine, Palvidis and Cooper refined this idea further and applied it to detect what they termed as "the face of fear". Exploiting the fact that specific activities are associated with characteristic, facial thermal "signatures", they focussed a Raytheon thermal camera on volunteer human faces to detect these.
When a volunteer was photographed before and during the task of chewing gum, the camera image of his jaw and chin region lit up within a fraction of a second, as he began chewing. Then they had a group of six volunteers facing the thermal camera and without any warning, startled them with a sudden loud noise. As the men were frightened with the sudden noise, their eyes musculature heated up and blood was drawn away form the cheeks. The camera recorded the thermal effects at distinguishable signals. The investigators concluded that facial thermal signatures can convey the psychological state of a person without physical contact.
The hot face of deception
In their latest experiments reported in Nature, they had a bunch of human volunteers commit a mock crime. The "crime" was to stab a dummy human figure or a mannequin, rob it of the $20 that it had and take off.
The investigators then questioned them much as a policeman would, and the "thieves" were to assert that they are innocent. In contrast were some `control' volunteers who had no knowledge of the crime or the crime scene. Each one of the twenty subjects was scanned through a thermal imaging camera as he was questioned. Six of the eight "guilty" individuals were correctly identified as lying and guilty. And 11 of the 12 innocent ones were also confirmed as innocent.
In comparison, traditional lie detector polygraph questioning of the same twenty, done by trained experts of the US Department of Defence Polygraph Institute on the spot, identified six of the 8 as guilty and 8 of the 12 as clean. Thermal imaging technology was thus seen to be at least as good, if not a bit better, than traditional polygraph. And it is quicker, needs no physical contact of the subject, and no trained staff either. It could detect temperature changes as little as a fraction of a degree, and could therefore "see through the face of deception".
Time is thus not far away when, as you answer the questioning by the airline staff, a thermal camera faces you. And as you answer, for heaven's sake, do not blush or start admiring her pretty face! The flush of blood on your face may cast you apart for further questioning by unprettier and stockier men carrying big sticks. That could frighten you into taking on a "face of fear". Don't blush nor flush, be well behaved as you answer her and, of course be truthful!
Your iris is you
There is even more to your eye than meets the thermal camera's eye. And that is in your iris, the thin, membranous, coloured sheet that opens or closes the pupil wide or narrow to let in just the right amount of light into the eye. Not only does the iris give your eye its characteristic colour - the blue of Boris Becker, the honey-brown of Aishwarya Rai and the jet black of Katya, but in addition the finer patterns woven into its gossamer layers are as distinctive of an individual as his or her fingerprints are. The details of your iris are thus your own and match nobody else's (except perhaps your identical twin's). Methods are being perfected to exploit this individual eye-signature and detect and store it as data. It would, in the near future, lead to an iris data bank just as there are fingerprint data banks or the proposed DNA data banks. Unlike the latter two, iris analysis, data banking and retrieval does not require physical contact or material removal. An iris detection camera is being perfected by a company in the US, which foresees this scenario; you go to the automatic teller cash machine, stand before it and press a couple of buttons. The camera identifies you, checks you as OK and lets the machine dispense the cash you wanted to draw. No ATM card or bank card, just your iris profile which is registered by the camera, and matched and identified by the attached computer, and bingo, out comes your cash. Indeed there is more to your eye than meets the eye!
D. Balasubramanian
L. V. Prasad Eye Institute,
Hyderabad
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