Genius dogs learn new words after hearing them just four times, a study has found - making them as quick as three year olds. Dogs which have a special talent for remembering verbal cues can rapidly expand their vocabulary simply by playing with their owners, according to the research. Whisky, a four-year-old female Border Collie from Norway, and Vicky Nina, a nine-year-old female Yorkshire terrier from Brazil, were able to fetch the correct toy after being exposed to the object and its name just four times, despite not receiving any formal training. Scientists say these highly intuitive dogs are therefore able to learn new words at the same speed as toddlers aged two and three. To test whether most dogs would be as successful as Whisky and Vicky Nina at learning new words, 20 others were tested in the same way - but none showed any evidence of understanding the new toy names. This confirms that only very few dogs which are especially gifted are able to learn words quickly in the absence of formal training, the scientists concluded. However, the study did reveal that Whisky and Vicky Nina's memory of the new toy names decayed over time due to them only hearing the names a few times.