Dog's verbal tricks probe origin of language
A collie that is a wizard with words reveals the comprehension needed for language, even though he cannot speak
A word-learning pet dog has given scientists clues that some animals may have the comprehension necessary for language, even though they cannot actually talk.
Rico, a smart border collie, was spotted on television by Julia Fischer and her colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. With a "vocabulary" of 200 words, Rico showed exceptional ability in retrieving specific toys when asked to fetch them.
The researchers decided to test whether Rico's ability was based on understanding and if he could learn and remember new words. They placed a new toy among his favourites and asked Rico to fetch it, using the unfamiliar name. The dog nearly always did. This suggests that Rico is using a system called "fast-mapping", which young children use to learn new words by matching new words to new objects. The study is the first to show fast-mapping in animals.
"It shows that fast-mapping is not specific to humans, that it probably has a more general purpose in figuring things out in your world," says Fischer.
"Dog owners often boast about the communicative and social abilities of their pets, and this study seems to vindicate them," writes Paul Bloom, a psychologist at Yale University, US, in a commentary accompanying the study in the journal Science.
Finely-tuned articulation
Fischer adds the results suggest there may be reasons other than comprehension which have stopped language evolving in dogs and chimps.
"With the evolution of language the constraints are not on the comprehension side - that had all been in place before humans uttered a word," she told New Scientist. "The constraints are more on the production side."
Making the jump from comprehension to talking may require a change in neural organisation to give voluntary control and fine-tune articulation, she says.
Another hypothesis suggests that gesturing is a pre-requisite to language developing. "Primates have fabulous control of their hands, but they don't gesture," Fischer explains. "So this shows there must be more going on, perhaps in terms of social cognition."
Retrieval rate
To be sure that Rico's language skills were not based on visual prompts, the researchers placed 10 known items in a room, while Rico and his owner waited in another room. The owner asked Rico to go in fetch two randomly chosen items 20 times. Rico correctly fetched 37 out of 40 toys.
When a new toy was placed in the adjacent room with seven other familiar objects, Rico correctly retrieved the unfamiliar item in seven out of 10 sessions.
He was then tested four weeks later to see if he remembered the link between the novel word and the novel item. The learned toy was placed among four completely new toys, and four familiar ones. In three out of six sessions, Rico picked the right one. "This retrieval rate is comparable to the performance of three-year-old toddlers," write the researchers.
Rico may be an exceptionally bright and studious dog, admits Fischer "If he were human, we would call him a workaholic. He's so motivated, it's mind-boggling."
She also points out that dogs may be a special case in responding to human language because they have co-evolved with humans. But other animals like apes have also shown comprehension.
Another factor could be that border collies are working dogs and have been selected to respond to a shepherd's calls. But despite their word skills, they do not make easy pets, she warns, as they require a lot of exercise and attention.
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Sujet: human nature