In 2010, a team of researchers at the University of California, Davis set out to test the reliability of drug- and bomb-sniffing dogs.
The team assembled 18 police dogs and their handlers and gave them a routine task: go through a room and sniff out the drugs and explosives.
But there was a twist. The room was clean. No drugs, no explosives.
In order to pass the test, the handlers and their dogs had to go through the room and detect nothing.
But of 144 runs, that happened only 21 times, for a failure rate of 85 percent.
Although drug-sniffing dogs are supposed to find drugs on their own, the researchers concluded that they were influenced by their handlers, and that’s what led to such a high failure rate.