[...]
"They studied drivers for signs of nervousness, including pulsing carotid arteries, clenched jaws and perspiration. They also looked for supposed “indicators” of criminal activity, which can include such things as trash on the floor of a vehicle, abundant energy drinks or air fresheners hanging from rearview mirrors."
[...]
http://www.washingtonpost.com/sf/investigative/2014/09/06/stop-and-seize/
"They studied drivers for signs of nervousness, including pulsing carotid arteries, clenched jaws and perspiration. They also looked for supposed “indicators” of criminal activity, which can include such things as trash on the floor of a vehicle, abundant energy drinks or air fresheners hanging from rearview mirrors."
[...]
http://www.washingtonpost.com/sf/investigative/2014/09/06/stop-and-seize/