According to the BBC (14 December):
Callers using internet phone system Skype who might be tempted to tell a few porkies should beware – the user on the other end may have a lie detector. Skype is to offer the KishKish Lie Detector, which is made by BATM, as an add-on for customers.
It analyses audio streams over a Skype call in real time and illustrates the stress levels of the other person. [...] Paul Amery, director of Skype developer programme said: “This is a really excellent application, and the kind of thing we want to see more of.”
Gah! Firstly, I hate the idea of either testing my friends – or being tested by them – during our phone conversations. Secondly, the KishKish site explains that the add-on is based on Voice Stress Analysis, which has been shown – time (pdf) and time again – to be useless for detecting lies:
Voice Stress Analysis (VSA) is a type of lie detector which measures stress in a person’s voice. The use of Voice Stress Analysis (VSA) as a lie detector became popular in the late 1970s and 80s. In the 90s the first Computerized VSA (CVSA) systems came to out to the market. The CVSAT is now the truth verification device of choice in the law enforcement community as the number of law enforcement agencies utilizing the CVSAT continues to grow dramatically, proving the viability of the system for twenty-first century crime detection. The CVSAT is also being utilized by the US Military in the global war on terrorism.
(a) VSA machines are NOT lie detectors, any more than polygraph machines are – they claim to measure indicators of stress, which is not the same as measuring deception.
(b) Who says the CVSAT is the ‘truth verification device of choice’ for law enforcement? It is not used in law enforcement agencies in the UK. VSA use is widespread in the USA, but just because many agencies use it does not mean that its ‘viability’ is proved. The US military are no longer using it, after a Pentagon study proved it detected lies at a rate of chance.
The bottom line: VSA is junk science. If you want a system with the same accuracy rate, I’ll sell you a penny – a coin toss gives the same success rate in detecting lies.
Paul Amery might want to see more of this kind of thing but hopefully he’s in a minority…