How to ID a Terrorist: V Signs?

Trying to ID masked terrorists appearing in propaganda or execution videos is one of counterterrorism's biggest obstacles. But a researcher at Jordan's Mutah University and his team think they've found one physical tell that could prove invaluable: the victory sign formed by making the letter "V" with one's index and middle fingers, MIT Technology Review reports. In a study led by Ahmad Hassanat and posted in the arXiv scientific paper archive, the researchers used hand geometry that studied finger size and the angle between the fingers when flashing the V sign to come up with a unique biometric "fingerprint" to see if they could recognize individuals from such an indicator. "Identifying a person using a small part of the hand is a challenging task, and has, to the best of our knowledge, never been investigated," Hassanat and his team note.

The researchers had 50 male and female subjects of all ages make the V sign with their right hand. Scientists took multiple pictures of each hand with a cameraphone (much like a terrorist would "in the field"), creating a database of 500 photos. They then examined the shapes and sizes of "triangles" formed by drawing lines between the tips of the fingers, the lowest point in the "V," and two points on the palm, followed by an analysis of hand shapes. Combining these two techniques created an algorithm that picked out different V signs and matched them to subjects, with ID accuracy varying from 40% to 93%. The scientists say the technique shows "great potential," though the MIT magazine points out it needs to be done on a larger scale, and results need to be combined with other data to actually positively ID someone. Also, notes RT.com: "Terrorists could simply learn about the technology and stop making V signs." (Speaking of "V" shapes: why birds fly in this exact formation.)