New Scientist Tech reports on new surveillance systems that can detect violent behavior.

A computer vision system developed in the University of Texas in Austin, US, can already tell the difference between friendly behaviour, such as shaking hands, and aggressive actions like punching or pushing.

That's how they spell behavior in the New Scientist, so don't get on my case. The system has already been adopted for home web cam use, the new software easily flagged this test clip:

Surveillance system spots violent behaviour [New Scientist]