March 5 (UPI) -- Humans have trained dogs to sniff out all sorts of targets, whether its a person buried by an avalanche or illegal drugs hidden in a suitcase. But until now, scientists hadn't explored how dogs conceive their smell-driven searches.
New research suggests dogs don't simply think about the reward they associate with a target smell, they produce a visualization, or mental image, of the target itself.
The new study, described this week in the Journal of Comparative Psychology, involved 48 dogs, 25 of whom were being trained as police or search and rescue dogs. The other 23 were untrained family dogs.
In an initial test, two of each dog's favorite toys were selected. The dogs were put onto the scent of one of the two toys. At the end of the trail scent, the dogs found either the toy linked with the scent, the normal condition, or their other favorite toy, the surprise condition.
Half the dogs were led to the normal condition, and the other half were led to the surprise condition. Researchers observed the responses of each dog.
"From my experience in other studies, I had assumed that the surprise would be measurable, in that the dogs would behave differently in the surprise condition than they would in the normal condition," Juliane Bräuer, researcher at the Max Planck Institute for the Science of Human History in Germany, said in a news release. "In fact, quite a few dogs showed interesting behavior, especially in the first round of the surprise condition, which we called 'hesitation:' although they had obviously noticed the toy, they continued to search via smell, probably for the toy that had been used to lay the scent trail."
Researchers found the surprise effect dissipated in follow up tests, possibly because the dogs began to associate both scenarios with playtime.
Still, scientists believe the initial tests prove the dogs have some basic conception of the target they're searching for.
Interestingly, the research also showed family dogs, after just a few tests runs, became just as efficient as professionally trained dogs at tracking down the toys. Scientists hope additional testing will provide new insights into the cognitive processes involved in canine searches.