Lie Detector Charlatans
This is worth reading:
Five years ago I wrote a Language Log post entitled "BS conditional semantics and the Pinocchio effect" about the nonsense spouted by a lie detection company, Nemesysco. I was disturbed by the marketing literature of the company, which suggested a 98% success rate in detecting evil intent of airline passengers, and included crap like this:
The LVA uses a patented and unique technology to detect "Brain activity finger prints" using the voice as a "medium" to the brain and analyzes the complete emotional structure of your subject. Using wide range spectrum analysis and micro-changes in the speech waveform itself (not micro tremors!) we can learn about any anomaly in the brain activity, and furthermore, classify it accordingly. Stress ("fight or flight" paradigm) is only a small part of this emotional structure
The 98% figure, as I pointed out, and as Mark Liberman made even clearer in a follow up post, is meaningless. There is no type of lie detector in existence whose performance can reasonably be compared to the performance of finger printing. It is meaningless to talk about someone's "complete emotional structure", and there is no interesting sense in which any current technology can analyze it. It is not the case that looking at speech will provide information about "any anomaly in the brain activity": at most it will tell you about some anomalies. Oh, the delicious irony, a lie detector company that engages in wanton deception.
So, ok, Nemesysco, as I said in my earlier post, is clearly trying to pull the wool over people's eyes. Disturbing, yes, but it doesn't follow from the fact that its marketing is wildly misleading that the company's technology is of no merit. However, we now know that the company's technology is, in fact, of no merit. How do we know? Because two phoneticians, Anders Eriksson and Francisco Lacerda, studied the company's technology, based largely on the original patent, and and provided a thorough analysis in a 2007 article Charlatanry in forensic speech science: A problem to be taken seriously, which appeared in the International Journal of Speech Language and the Law (IJSLL), vol 14.2 2007, 169–ÃÂ193, Equinox Publishing. Eriksson and Lacerda conclude, regarding the original technology on which Nemesysco's products are based, Layered Voice Analysis (LVA), that:
Any qualified speech scientist with some computer background can see at a glance, by consulting the documents, that the methods on which the program is based have no scientific validity.
Most of the lie detector industry is based on, well, lies.
Posted on May 6, 2009 at 12:14 PM • 40 Comments