But the developers of the system said it could be used alongside polygraph machines to increase their reliability. Polygraph machines measure changes in a person's body related to the stress of telling a lie, but cannot tell what the lie is. The Facial Action Coding System can look for hidden facial expressions that reveal what a person is really feeling when he is telling that lie. The kind of approach we're working on provides a way to quantify this information that will make it useable. The Automated Face Analysis Program uses 'Perspective Alignment' to account for rigid head movements.
Some critics remain skeptical of the face readers' potential.
I've never seen anybody yet who had a discernable lying expression on their face. Even current polygraph operators doubted the face readers' usefulness. Don Weinstein, the president of American Polygraph Association, said polygraph machines measure involuntary responses to lying. Facial muscles, which a person can control at will, are just too unreliable to be used as proof of a crime. It absolutely astounds me.