Chaser the border collie has swapped sheep and shepherds for syntax and semantics. The black and white sheepdog has not only learnt and remembered more than 1,000 proper nouns but she has also grasped some of the finer points of English grammar, according to researchers in the United States who have studied her.

University academics who have tested her knowledge believe the results show the dog learned, like children, to respond in the right way to different types of words. "Our findings showed that Chaser was successful in demonstrating syntax and semantic understanding on 75 per cent of the trials," say the researchers. They say the dog was able to demonstrate understanding of nouns and verbs which represents a giant leap in her "understanding of language and opens the door for learning further language skills."

The study, involving more than seven years of teaching and research on the border collie, was published in the journal Learning and Motivation. The dog, born in 2004, lived in the home of the researchers, primarily as a member of the family, but also as a target for research.

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In the first three years, she learned and remembered 1,022 proper nouns. The objects included more than 800 cloth animals, 116 balls, 26 Frisbees, and another 100 plastic toys. There were no duplicates, and each had unique features so it could be identified. Each was also given a distinctive name, like elephant or Santa Claus.

The dog built up and maintained knowledge of the nouns over a 32-month period. Each month, she was tested on the entire vocabulary, and each time she was able to identify correctly more than 95 per cent of the objects.

The researchers say Chaser's ability to learn and remember so many words, involving discrimination, memory, and other skills, revealed clear evidence of the potential for learning to understand human language.

Not content with their canine's memory skills, the researchers set about teaching the dog grammar. The object of this research was to investigate Chaser's ability to understand the syntax and semantics of sentences consisting of three elements of grammar – a prepositional object, a verb, and a direct object – such as "to ball take Frisbee" and the inverse "to Frisbee take ball" or "to A take B" and the inverse, "to B take A".

Not only did it require the dog to recognise the 100 toys chosen for the experiment, but she also had to take the right ones to the correct destination. Findings showed that Chaser was successful in demonstrating syntax and semantic understanding on 18 of the 24 trials, or 75 per cent of the time. She could also respond to novel objects.

"Thus, after learning the name of the objects, she was able, as are children, to understand the meaning of the sentences even though the objects had never been used in the syntax sentence," say the researchers from Wofford College in North Carolina.

"The combined findings of the three studies support the conclusion that Chaser did, indeed, process and retain memories of prepositional and direct objects.

"The findings closely match the data obtained in dolphin studies involving sentences consisting of three elements of grammar.

"We propose that Chaser's understanding of the three elements of grammar in sentences evolved out of her intensive training for learning the meaning of specific words, and different types of words developed greater sensitivity for verbal symbols and referential cues. In some way, whether by cognitive processes, associative processes, by the inherent properties of different types of words themselves, or by the combination of all three mechanisms, Chaser learned, as do children, to respond appropriately to different classes of words."

They said that the experiments revealed that the dog's understanding of words was not simply confined to memorising strings of words by rote. "Rather, in some way, her brain is partially constructed like that of humans," the researchers said.