Sniffer dogs could pick up on their handler's "unconscious bias" if they have prejudiced beliefs, the Prison Service has warned in new guidance.
The 116-page document, published last week for staff, is based on a research study carried out at the University of California, Davis campus - and it warns that dog handlers must be aware of the risk of "unconscious bias" whilst at work.
The research suggests dogs are so good at reading the body language of their handlers, that when he or she is suspicious, the dog will pick up on it.
Dogs are widely used on prison wings and when visitors arrive at jails, and studies have shown their scent powers make them better at detection than the latest high-tech machines.
In the California study, dog handlers were asked to take their dogs around a specially-prepared area to check for explosives.
There were, in fact, no explosives – but some sections had hidden sausages which could have attracted the dogs’ interest, while other sections had red warning signs which could have attracted the handlers’ interest.
The greatest number of false positive alerts – more than 200 of them – was given in the areas with the red warning signs.
This indicates that if a handler holds racist or prejudiced views and generally suspects that black or Asian people are more likely to have forbidden items, their dog will be more likely to get it wrong when indicating suspicions for the same ethnic groups.
'Handler’s beliefs and expectations can have an influence on detection-dog performance'
The Prison Service guidance said: "A study conducted by UC Davis found that handler’s beliefs and expectations can have an influence on detection-dog performance.
"This is particularly significant as it suggests that handlers will need to be aware of issues around unconscious bias.”
The guidance concluded: “Dogs have been deployed by HMPPS for over 50 years, for their abilities to detect illicit items, and as a less lethal use of force asset during serious incidents.
"From a review of available literature, we can determine that dogs are an effective security tool in the fighting and prevention of crime.
'Despite the costs related to feeding, vet care, and training, dog effectiveness studies show dogs deliver excellent value for money.”