题型：阅读理解 题类：模拟题 难易度：普通
内蒙古包钢第一中学2018届高三英语适应性考试（一）试卷
If your dog looks pleased to see you—it is probably because it loves the particular way you smell.
The scent (气味)of a familiar human apparently lingers like perfumein the animal's brain—where it causes an instinctive emotional response, research reveals.
Our scent acts on a part of the canine (犬科的) brain associated with reward and the strongest reactions are produced by humans that pets know best, say scientists in America.
Gregory Bern, of Emory University in Atlanta, said, “While we might expect that dogs should be highly tuned to the smell of other dogs, it seems that the 'reward response' is reserved for their humans. When humans smell the perfume of someone they love, they may have an immediate, emotional reaction that's not necessarily cognitive (认识的). So is it in dogs. But since dogs have a more sensitive smell than humans, their responses would likely be even more powerful than the ones we might have. In our experiment, however, the owners of the dog were not physically present. The canine brain responses were being caused by something distant in space and time. It shows that dogs' brains have these mental representations of us that persist when we're not there.”
The experiment involved 12 dogs of various kinds by brain scans while five different scents were placed in front of them. The scent samples (样本)came from the subject (接受试险者) itself, a dog the subject had never met, a dog living in the subject's household. The familiar human scent samples were taken from someone else from the house other than the handlers during the experiment, so that none of the scent donors were physically present.
The results showed all five scents gained a similar response in parts of the dogs brains involved in detecting smells. Responses were significantly stronger for the scent of familiar humans, followed by that of familiar dogs. The findings showed dogs reacted strongest to the scent of familiar humans even when they were not there. Pets trained as help or therapy dogs showed greater brain activity than the other dogs in the test.
Researchers say the findings could improve the way to select animals helping wounded old soldiers or disabled people.
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