The ability of animals to recognise human feelings has become a concern for the prison service, which is worried that handlers of sniffer dogs may be communicating “unconscious bias” to their canine charges.
New guidance from Her Majesty’s Prison and Probation Service cites an American study that found detection dogs could be influenced by a handler’s “beliefs and expectations”.
If a handler appeared certain that an incriminating scent would be present at a search location — whether it was drugs, explosives, alcohol or any other substance or object a sniffer dog is trained to detect — the dog would recognise its handler’s confidence and could return a false positive alert.
“The explanation is thought to be that dogs are so good at reading the body language of their handlers, that when the handler is suspicious, the dog will pick up on it,” noted Inside Time, a monthly newspaper distributed to British prisons.
The paper added: “The finding raises the prospect that if a dog handler holds racist views and generally suspects that black or Asian people are more likely to carry drugs than white people, his or her dog will be more likely to indicate false drug finds when sniffing black or Asian people.”
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The guidance stresses that sniffer dogs are “an effective security tool in the fighting and prevention of crime”.
Last year the government announced plans to increase the number of sniffer dogs used in jails to more than 800. They detected 2,200 illegal items over the year, including large quantities of drugs and illicit mobile phones.
Official concern over infecting dogs with prejudice recalls the “Clever Hans” case of the early 1900s, in which a horse’s German owner claimed to have taught it to count by tapping its hoof on the ground in answer to simple mathematical questions. Officials suspecting fraud ordered an investigation, which found that the horse watched its questioner carefully, and stopped tapping its hoof when it detected changes in the demeanour of onlookers suggesting it had arrived at the correct number of taps.
In the case of sniffer dogs, the University of California study concluded, handler influence was similarly likely to “affect outcomes of scent detection dog deployments”.
